View Source ERTS Release Notes

This document describes the changes made to the ERTS application.

Erts 15.1.2

Fixed Bugs and Malfunctions

A bug has been fixed where receiving an SCTP message with gen_sctp could waste the first fragments of a message and only deliver the last fragment.
This happened with low probability when the OS signaled that the socket was ready for reading in combination with an internal time-out retry.
A bug has been fixed with a lingering time-out from after an SCTP connect that could stop the flow of incoming messages on an active gen_tcp socket.
Own Id: OTP-19235 Aux Id: ERIERL-1133, PR-8837
An boolean option non_block_send for SCTP, has ben added to be able to achieve the old behaviour to avoid blocking send operations by passing the OS network stack error message ({error,eagain} through.
Own Id: OTP-19258 Aux Id: OTP-19061, ERIERL-1134
The call gen_tcp:send/2 could hang indefinitely despite having set the send_timeout option for the following unfortunate combination of circumstances:
- The socket has to be in passive mode.
- All output buffers had to be filled util the high_watermark was hit, causing the gen_tcp:send/2 operation to block.
- While the send operation was blocked, a gen_tcp:recv/2,3 call had to be done from a different process. It had to block, waiting for data for a while before completing the operation, and the received packet had to fill at least 75% of the receive buffer.
Under these circumstances he information that a send operation was waiting got lost, so the send operation that blocked in the first placed would never return. The data it had would be sent, though, and send operations from other processes, still work.
This bug has been fixed.
Own Id: OTP-19267 Aux Id: GH-6455, OTP-18520, ERIERL-1138, PR-8892
In rare circumstances, in code that matches multiple tuples, the JIT could generate code that would raise a badmatch exception even if the given tuples were correct.
Own Id: OTP-19268 Aux Id: GH-8875, PR-8895
Fixed beam crash that could happen if resetting call_time or call_memory trace counters of a function while it is called. Bug exists since OTP R16.
Own Id: OTP-19269 Aux Id: GH-8835, PR-8897

Erts 15.1.1

Fixed Bugs and Malfunctions

On Windows, successive failed socket calls caused socket to become "uninitialized".
Own Id: OTP-19251 Aux Id: #8853
The socket framework fails to start on a IPv6-only Windows machine.
Own Id: OTP-19254 Aux Id: #8848

Erts 15.1

Fixed Bugs and Malfunctions

The erl -man example has been corrected to not consider values set in ERL_ZFLAGS and stop parsing arguments when a -- is encountered.
Own Id: OTP-19098 Aux Id: PR-8478
Compiler warnings for Windows I/O back-end have been silenced.
Own Id: OTP-19113
Bugs related to return_to trace have been fixed. It did not work for more than once trace session and it did sometimes not trigger for exceptions.
Own Id: OTP-19122
Potential deadlocks while writing a crash dump have been eliminated.
Own Id: OTP-19133 Aux Id: PR-8521, GH-8498
When loading a damaged or too old BEAM file, the runtime system could crash.
Own Id: OTP-19153 Aux Id: PR-8623
A scheduler thread could get stuck when deleting a memory allocator carrier when adjacent carriers were deleted and/or inserted simultaneously by other schedulers. This in turn could cause the other schedulers to get stuck as well.
Own Id: OTP-19154 Aux Id: GH-8613, PR-8627
Statistics for number of carriers in a shared pool after calling instrument:allocations or instrument:carriers are now correct. Also, a potential bug in carrier block scanning was eliminated.
Own Id: OTP-19166 Aux Id: PR-8636
A race in the kTLS flavour of SSL distribution has been fixed so that inet_drv.c doesn't read ahead too much data, which could cause the kTLS encryption to be activated too late when some encrypted data had already been read into the inet_drv.c buffer as unencrypted.
Own Id: OTP-19175 Aux Id: GH-8561, PR-8690
Fixed an emulator crash relating to compressed ETS tables.
Own Id: OTP-19176 Aux Id: PR-8683
A function (encode_sockaddr) was called with superfluous argument, on Windows, in the net nif.
Own Id: OTP-19181
Fixed a crash that could happen on reallocation failure.
Own Id: OTP-19192
Man pages are now available for erl, erlc, dialyzer, and all other programs that are included in Erlang/OTP.
Own Id: OTP-19201 Aux Id: PR-8740
A previous correction in the Erlang/OTP 27.0.1 emergency patch had the unfortunate side effect of sometimes causing an unnecessary fullsweep (major) garbage collection instead of a generation (minor) garbage collection. This has been corrected.
Own Id: OTP-19209 Aux Id: PR-8751, PR-8539
Fixed trace matchspec functions trace and enable_trace to use the session tracer when enabling trace flags on untraced processes.
Own Id: OTP-19211 Aux Id: GH-8657
Fixed a typo in the type spec for erlang:garbage_collection_defaults/0.
Own Id: OTP-19215 Aux Id: PR-8757
Corrected socket:ioctl for genaddr (SIOCGENADDR).
Own Id: OTP-19216
The support for Transparent Huge Pages has been disabled on non-amd64 Linux systems.
Own Id: OTP-19219 Aux Id: PR-8702
Fixed a race condition on Windows when upgrading from -noshell to a shell that would cause Erlang to crash with the error:
```
{'GetOverlappedResult',
  'The I/O operation has been aborted because of either a thread exit or an application request.'}.
```
Own Id: OTP-19220 Aux Id: PR-8774

Improvements and New Features

Added functions getservbyname and getservbyport to the net module.
Own Id: OTP-19101 Aux Id: OTP-18835
Introduced enet | esock variants of inet functions, either when called with sockets, with explicit inet_backend config or with the e inet_backend kernel config option.
Own Id: OTP-19132 Aux Id: OTP-19101
Optimize process and port creation when such tracing is not enabled by any trace session.
Own Id: OTP-19167 Aux Id: PR-8655
Compiler warnings for some removed functions have been corrected to point out the correct replacement functions.
Own Id: OTP-19186 Aux Id: PR-8709
A boolean option read_ahead has been implemented for gen_tcp, default true, to facilitate not reading past (caching data) the end of a packet. In particular, for kTLS, caching data could read in data that was supposed to be decrypted by the platform's network stack, before crypto parameters could be activated.
Own Id: OTP-19199 Aux Id: OTP-19175, GH-8561, GH-8690, GH-8785
The zip module has been updated with support for:
- zip64 archives - Archives larger than 4GB or with more than 2^32 entries.
- extended timestamps - Higher resolution and in UTC.
- UID/GID - Save and extract the original UID/GID.
- Fixes so that permission mode attributes are correctly read and set for files in archives.
- zip:list_dir/2 now also returns directories, not only files. (You can disable this behaviour by using the option skip_directories).
Various bugs in the original implementation have also been fixed, such as:
- Correctly encode and decode the DOS timestamps for entries within an archive (that is the non-extended timestamp).
- Fix DOS timestamps to be set to localtime instead of UTC (use extended timestamps for UTC timestamps).
- Use the unix file attributes read from disk when creating archives instead of setting everything to 644.
Own Id: OTP-19214 Aux Id: PR-8765

Erts 15.0.1

Fixed Bugs and Malfunctions

In rare circumstances the JIT could do an unsafe in-place update of a tuple.
Own Id: OTP-19108 Aux Id: PR-8539
When a port command crashed in the inet driver during gen_tcp:send/2, a monitor 'DOWN' message could be left lingering in the caller's mailbox. This has now been fixed.
Own Id: OTP-19121 Aux Id: GH-8484
'DOWN' messages originating from a monitored port, contained the atom process instead of the atom port as the third element when the exit reason was not an immediate term.
Own Id: OTP-19123 Aux Id: GH-8484, PR-8546
Fix so that the options to enable Transparent Huge Page alignment of the Erlang VM executable are only applied to the Erlang VM and not other native programs such as erlc and dialyzer. This bug was introduced in Erlang/OTP 27.0.
Own Id: OTP-19137 Aux Id: GH-8574
When no time warp mode was enabled, a smaller Erlang monotonic time could be read than a previously read time, i.e., breaking the monotonic property. The runtime system will abort when detecting an issue like this since OTP 24.3.4.17 and OTP 25.0.
Up until OTP 25 no time warp mode is the default. As of OTP 26 multi time warp mode is the default.
Own Id: OTP-19147 Aux Id: ERIERL-1043, ERIERL-1106, PR-8619
When calling trace:function(Session, _, true, [meta]) the meta tracer was incorrectly set to be the calling process. Now it's set to the session tracer as expected.
Own Id: OTP-19151 Aux Id: PR-8616, GH-8614

Erts 15.0

Fixed Bugs and Malfunctions

Bugs in how erl -extra interacts with passing flags via ERL_*FLAGS or -args_file have been fixed.
Own Id: OTP-18766 Aux Id: PR-7639
Fixed a bug that prevented the emulator from building on recent versions of Yocto Linux.
Own Id: OTP-18918 Aux Id: PR-7952
Fixed spectre mitigation configure test to work with GCC patches to always add -fcf-protection=full.
Own Id: OTP-18928 Aux Id: PR-8006
A call to socket:[recv|recvfrom|recvmsg]/* with Timeout = 0 on Windows could cause a (case clause) crash if data is immediately available.
Own Id: OTP-19063 Aux Id: OTP-18835
Fix bug on Windows where exit_status would not be sent when a port exits after the stdin/stdout handles have been closed.
Own Id: OTP-19077 Aux Id: PR-8324

Improvements and New Features

Refactored how the JIT handles POSIX signals and how they affect thread stacks, allowing us to use the native stack register for Erlang stacks on more platforms.
Notably, containers built on 64-bit x86 Alpine Linux images will now perform much better in sequential code. As an example, running dialyzer over the OTP code base finishes about 15% quicker.
Own Id: OTP-18568 Aux Id: PR-7174
The instrument module can now track allocations on a per-process or per-port basis.
Own Id: OTP-18577 Aux Id: PR-7236
The pid field returned from erlang:fun_info/1,2 is now always the pid for the init process of the local node, not the pid for the actual process that created the fun.
POTENTIAL INCOMPATIBILITY
Own Id: OTP-18594 Aux Id: PR-7274
By default, escripts will now be compiled instead of interpreted. That means that the compiler application must be installed.
POTENTIAL INCOMPATIBILITY
Own Id: OTP-18639 Aux Id: PR-7348
A binary returned from the socket receive functions is no longer created as a sub binary of an often large receive buffer binary (socket option {otp,rcvbuf}). This avoids space waste, trusting the allocators to implement reallocation efficiently.
Own Id: OTP-18642 Aux Id: GH-6152, PR-7465
The default process limit has been raised to 1048576 processes.
Own Id: OTP-18699 Aux Id: PR-7388
The erlang:system_monitor/2 functionality is now able to monitor long message queues in the system.
Own Id: OTP-18709 Aux Id: PR-7651
The erl command now supports the -S flag, which is similar to the -run flag, except that it will pass all arguments up to end of the command line to the called function. (The -run flag will not pass arguments beginning with a hyphen.) Another difference is that -S will always call a function with one argument, passing an empty list if no arguments were given.
Own Id: OTP-18744 Aux Id: PR-7470
When implementing an alternative carrier for the Erlang distribution, a separate input handler process may now be registered, using erlang:dist_ctrl_input_handler/2, also in the case when the distribution controller is a port.
Own Id: OTP-18774 Aux Id: PR-7110
The call stack trace has now been added to the error reported by erlang:process_flag/2 when max_heap_size limit has been exceeded.
Own Id: OTP-18779 Aux Id: PR-7592
-callback attributes have been added to erl_tracer.
Own Id: OTP-18794 Aux Id: PR-7703
For inet_backend = socket, setting the active socket option alone, to once, true or N has been optimized, as well as the corresponding data delivery.
Own Id: OTP-18835
New functions socket:sendv/* for sending I/O vectors have been added.
Own Id: OTP-18845
Socket options that take string now also accept binaries.
Own Id: OTP-18849 Aux Id: PR-6510
Native coverage support has been implemented in the JIT. It will automatically be used by the cover tool to reduce the execution overhead when running cover-compiled code.
There are also new APIs to support native coverage without using the cover tool.
To instrument code for native coverage it must be compiled with the line_coverage option.
To enable native coverage in the runtime system, start it like so:
```
$ erl +JPcover true
```
There are also the following new functions for supporting native coverage:
- code:coverage_support/0
- code:get_coverage/2
- code:reset_coverage/1
- code:get_coverage_mode/0
- code:get_coverage_mode/1
- code:set_coverage_mode/1
Own Id: OTP-18856 Aux Id: PR-7856
Changed the default value of the command line flag -code_path_choice to strict.
Note that for application systems using archives, it is necessary to add the code_path_choice relaxed to the command line that invokes erl.
Own Id: OTP-18894 Aux Id: PR-7243
Added module loading to erl -init_debug printouts.
Own Id: OTP-18929 Aux Id: PR-8004
When the runtime system halts, it performs various flush operations before terminating. By default there is no limit on how much time the flush operations are allowed to take. A new halt flush timeout functionality has been introduced which can be used for limiting the amount of time that the flushing operations are allowed to take. For more information see the documentation of the flush_timeout option of the erlang:halt/2 BIF and the documentation of the erl +zhft <Timeout> command line flag.
Own Id: OTP-18938 Aux Id: PR-8035, GH-7438
Optimized code loading by moving certain operations from the code server to the caller.
Own Id: OTP-18941 Aux Id: PR-7981
Updated asmjit to version a465fe71ab3d0e224b2b4bd0fac69ae68ab9239d
Own Id: OTP-18942
The deprecated functions in zlib have been removed. That includes inflateChunk/{1,2}, getBufSize/1, setBufSize/2, the CRC32 functions, and the Adler checksum functions.
Own Id: OTP-18950
The documentation has been migrated to use Markdown and ExDoc.
Own Id: OTP-18955 Aux Id: PR-8026
Safe destructive update of tuples has been implemented in the compiler and runtime system. This allows the VM to update tuples in-place when it is safe to do so, thus improving performance by doing less copying but also by producing less garbage.
Example:
```
-record(rec, {a,b,c}).

update(#rec{a=needs_update,b=N}=R0) ->
    R = R0#rec{a=up_to_date},
    if
        N < 0 ->
            R#rec{c=negative};
        N == 0 ->
            R#rec{c=zero};
        N > 0 ->
            R#rec{c=positive}
    end.
```
The record updates in each of the three clauses of the if can safely be done in-place, because variable R is not used again.
Own Id: OTP-18972 Aux Id: PR-8090
The obsolete and undocumented support for opening a port to an external resource by passing an atom (or a string) as first argument to open_port(), implemented by the vanilla driver, has been removed. This feature has been scheduled for removal in OTP 27 since the release of OTP 26.
Own Id: OTP-18976 Aux Id: PR-7125
An optional NIF callback ERL_NIF_OPT_ON_UNLOAD_THREAD to be called by all scheduler threads when a NIF library is unloaded. Used for releasing thread specific data. Can be set with function enif_set_option.
Own Id: OTP-18977 Aux Id: PR-7809
There is a new module trace in Kernel providing the same trace functionality as erlang:trace/3 and erlang:trace_pattern/3, but with the addition of dynamic isolated trace sessions.
Own Id: OTP-18980
Added the +MMlp on|off emulator option to let the mseg allocator use "large pages" (sometimes known as "huge pages" or "super pages"). This currently only affects super-carrier allocations, but may be extended in the future.
Own Id: OTP-18984 Aux Id: PR-7977
inet_backend = socket has been optimized and reworked to be more compatible with the original inet_backend = inet.
Own Id: OTP-19004 Aux Id: OTP-18835
The socket documentation has been reworked, and due to that a few details were fixed:
- socket:is_supported/1 now returns true for example for protocols that is a "category", not an item.
- socket:cancel_monitor/1 no longer badargs for a monitor that was set by another process, instead it returns false as for other unknown reference()s.
Own Id: OTP-19054

Erts 14.2.5.3

Fixed Bugs and Malfunctions

A race in the kTLS flavour of SSL distribution has been fixed so inet_drv.c doesn't read ahead too much data which could cause the kTLS encryption to be activated too late when some encrypted data had already been read into the inet_drv.c buffer as unencrypted.
Own Id: OTP-19175 Aux Id: GH-8561, PR-8690

Erts 14.2.5.2

Fixed Bugs and Malfunctions

When no time warp mode was enabled, a smaller Erlang monotonic time could be read than a previously read time, i.e., breaking the monotonic property. The runtime system will abort when detecting an issue like this since OTP 24.3.4.17 and OTP 25.0.
Up until OTP 25 no time warp mode is the default. As of OTP 26 multi time warp mode is the default.
Own Id: OTP-19147 Aux Id: ERIERL-1043, ERIERL-1106, PR-8619
A scheduler thread could get stuck when deleting a memory allocator carrier when adjacent carriers were deleted and/or inserted simultaneously by other schedulers. This in turn could cause the other schedulers to get stuck as well.
Own Id: OTP-19154 Aux Id: GH-8613, PR-8627

Erts 14.2.5.1

Fixed Bugs and Malfunctions

A call to socket:[recv|recvfrom|recvmsg]/* with Timeout = 0 on Windows could cause a (case clause) crash if data is immediately available.
Own Id: OTP-19063 Aux Id: OTP-18835
When a port command crashed in the inet driver during gen_tcp:send/2, a monitor 'DOWN' message could be left lingering in the caller's mailbox. This has now been fixed.
Own Id: OTP-19121 Aux Id: GH-8484
'DOWN' messages originating from a monitored port, contained the atom process instead of the atom port as the third element when the exit reason was not an immediate term.
Own Id: OTP-19123 Aux Id: GH-8484, PR-8546

Erts 14.2.5

Fixed Bugs and Malfunctions

gen_sctp:send/3,4 now waits for the send to complete instead of returning an OS result such as {error, ewouldblock}.
Own Id: OTP-19061
ETS functions did not properly handle keys containing maps, sometimes matching too many or too few objects.
Own Id: OTP-19070 Aux Id: GH-8385
Fix CPU quota determination for cgroups.
The bug was introduced through OTP-18999.
Own Id: OTP-19071 Aux Id: OTP-18999 PR-8380

Improvements and New Features

Added a warning to open_port/2 regarding the BadBatBut attack affecting Windows.
Own Id: OTP-19069

Erts 14.2.4

Fixed Bugs and Malfunctions

Fixed CPU quota determination for cgroup version 2
Own Id: OTP-18999 Aux Id: GH-7928
Fix faulty reduction counting in exiting process which could cause it to do unnecessary yielding.
Own Id: OTP-19014
Fix bug in re:run/3 where if an invalid UTF-8 subject was given, re:run could get stuck in an infinite loop. Bug was introduced in Erlang/OTP 22.1.
Own Id: OTP-19015 Aux Id: ERIERL-682
On AArch64 (ARM64), Erlang code using bit syntax construction compiled using Erlang/OTP 24 could crash the runtime system when run in Erlang/OTP 26.2.3.
Own Id: OTP-19021 Aux Id: GH-8238, PR-8248
Calling erlang:trace/3 with first argument one of ports, processes, existing_ports, existing_processes, existing or all, could cause emulator crash if a dirty scheduler was executing a simultaneous trace action.
Own Id: OTP-19034
Fixed an integer overflow when the monotonic time unit reported by the operating system was greater than 10 and lower than 100 microseconds.
Own Id: OTP-19036 Aux Id: GH-8186
Fix option reuseaddr for FreeBSD 14
Own Id: OTP-19041
When a traced process executing on a dirty scheduler received an exit signal, the dirty scheduler could use the wrong thread specific data which could lead to a crash.
Own Id: OTP-19043 Aux Id: PR-8342
Fixed a more or less harmless bug that caused time correction of Erlang monotonic time to become slightly off on Windows platforms when QueryPerformanceCounter() was used as OS monotonic time source.
erlang:system_info(os_monotonic_time_source) now also returns information about used resolution which not always corresponds to the resolution of the OS monotonic time source.
Own Id: OTP-19048 Aux Id: PR-8343
When using IPv6, classic gen_udp failed to add (group) membership (drop was used instead).
Own Id: OTP-19049 Aux Id: #8176
Fix bug on Windows where "Unknown event: 2" would be printed to the console.
Own Id: OTP-19060

Improvements and New Features

Checks for monotonicity of monotonic time have been improved so that Erlang and OS monotonic time are checked separately.
A new configure argument --enable-ensure-os-monotonic-time has also been added. It enables functionality ensuring the monotonicity of monotonic timestamps delivered by the OS. When a non-monotonic timestamp is detected, it will be replaced by the last delivered monotonic timestamp before being used by Erlang's time functionality. Note that you do not want to enable this unless the OS monotonic time source on the system fails to produce monotonic timestamps. This since ensuring the monotonicity of OS monotonic timestamps will hurt scalability and performance of the system.
Own Id: OTP-19044 Aux Id: ERIERL-1043, PR-8342
For severe errors, when the `socket` module terminates the Erlang VM, now an erl_crash.dump is produced, to facilitate post mortem debugging.
Own Id: OTP-19058

Erts 14.2.3

Fixed Bugs and Malfunctions

Fixed compile warning in erl_nif.c for gcc-13.
Own Id: OTP-18906 Aux Id: PR-7930
Fix C++ compile error for macros enif_select_read and friends.
Own Id: OTP-18907 Aux Id: PR-7932
Fixed a name clash on Solaris that prevented the JIT from being built.
Own Id: OTP-18940 Aux Id: GH-8024
Fix termcap detection on solaris.
Own Id: OTP-18952 Aux Id: PR-8025
Fix heap corruption bug that could cause runaway memory consumption due to circular offheap list at process exit. Other symptoms may also be possible. Bug exists since OTP 25.0.
Own Id: OTP-18971 Aux Id: GH-8044
Do not clear tracing in old module instance if load fails with 'not_purged'.
Own Id: OTP-18979
When exceeding the `max_heap_size` limit in a garbage collection initiated by some bit syntax operations, the process would not always terminate immediately.
Own Id: OTP-18982
The code server could be hanging if a module with on_load function was loaded at the same time as another module was purged using erlang:purge_module directly.
Own Id: OTP-19006
A process optimized for parallel signal delivery could under some circumstances lose wakeup information. That is, the processes was not woken up to take care of the signal, so the signal would not be taken care of until the process was woken by another signal. Only processes configured with message_queue_data set to off_heap utilize this optimization.
Own Id: OTP-19008 Aux Id: GH-8119, PR-8201
Fix segfault when generating crashdump containing a fun places in persistent_term storage.
Own Id: OTP-19009 Aux Id: PR-8181
By default the JIT is disabled on Intel Macs, because of annoying poups on macOS Sonoma. It is now possible to explicitly enable the JIT on Intel Macs. Here is how: ./configure --enable-jit
Own Id: OTP-19011

Erts 14.2.2

Fixed Bugs and Malfunctions

32-bit runtime systems on most Unix like platforms could crash if a BIF timer was set with a huge timeout of more than 68 years into the future. In order for the crash to occur, the huge timer (at a later time than when it was set) had to become the nearest active timer set on the specific scheduler on which it was set. This could not happen on a system with only one scheduler since there would always be shorter timers in the system.
Setting a timer larger than 49 days on Windows could under rare circumstances cause the timeout to be delayed.
Own Id: OTP-18911 Aux Id: ERIERL-1023, PR-7983
Fix bug where the system installed openssl/md5.h would be confused with the vendored md5.h.
Own Id: OTP-18931 Aux Id: GH-7987 PR-7989
The JIT has now been disabled on x86 Macs to prevent annoying the "verifying shm-xyz" popups introduced in MacOS Sonoma.
ARM Macs are unaffected.
Own Id: OTP-18949
Garbage collection of a process on a dirty scheduler could collide with signal handling for that process causing a crash of the runtime system. This bug was introduced in OTP 25.3.2.8 and OTP 26.2.
Own Id: OTP-18957 Aux Id: GH-8051, PR-8088, OTP-18841

Erts 14.2.1

Fixed Bugs and Malfunctions

Removed unnecessary PCRE source tar-ball.
Own Id: OTP-18902

Erts 14.2

Fixed Bugs and Malfunctions

Fix erl.exe to to restore the console to its original state when exiting. This bug was introduced in OTP 26.0 and only happens when erl.exe is run in cmd.exe.
Own Id: OTP-18751 Aux Id: GH-7621 GH-7548
Fix faulty debug assert when page size is larger than 16kb, like on PowerPC. Did crash debug VM directly at start.
Own Id: OTP-18802
zlib will no longer randomly return garbage (negative) Adler32 checksums.
Own Id: OTP-18811 Aux Id: ERIERL-994
Replaced unintentional Erlang Public License 1.1 headers in some files with the intended Apache License 2.0 header.
Own Id: OTP-18815 Aux Id: PR-7780
A process with message_queue_data configured as off_heap could end up in an inconsistent state when being receive traced, inspected using process_info/2 with the message_queue_len item, or inspected using the break menu (CTRL-C). When it ended up in this inconsistent state, it was not enqueued into a run queue even though it was set in a runnable state.This also effected signals being sent to the process after it had gotten into this inconsistent state, in such a way that it was from this point not possible to communicate with it.
Own Id: OTP-18838 Aux Id: PR-7822, GH-7801
A race occurring when a process was selected for dirty execution simultaneously as it was scheduled for handling a signal could cause the process to end up in an inconsistent state. When it ended up in this inconsistent state, it was not enqueued into a run queue even though it was set in a runnable state. This also effected signals being sent to the process after it had gotten into this inconsistent state, in such a way that it was from this point not possible to communicate with it.
Own Id: OTP-18839 Aux Id: PR-7822, GH-7801
When a process had to to wait in the run queue for a long time before being selected for dirty execution, it could not receive signals. This caused inspection of such a process, for example using process_info/2, to take a long time.
This issue was introduced in OTP 25.3.2.6 and 26.1 when fixing an issue where a constant flow of signals prevented a process from being able to execute dirty.
Own Id: OTP-18841 Aux Id: PR-7822, GH-7801, OTP-18737
Fixed a bug in the JIT that miscompiled large select_val instructions.
Own Id: OTP-18842
Fix bug on Windows where large writes to standard_io could cause duplicate data to be written.
Own Id: OTP-18871 Aux Id: GH-7838
The struct ip_mreqn field imr_ifindex had got an incorrect byte order conversion that has been corrected.
Own Id: OTP-18880 Aux Id: GH-7736, PR-7761
On OTP 24 and OTP 25, incoming distributed messages larger than 64 KiB sent using an alias leaked memory if the alias had been removed prior to entering the node. This issue was not present on OTP 26.
Incoming distributed messages larger than 64 KiB sent using an alias which had been removed on the receiving node could crash the node. This crash was quite unlikely on OTP 24 and OTP 25, but very likely on OTP 26.
'DOWN' signals with exit reason larger than 64 KiB directed towards a process on a node with a not matching creation leaked memory on the receiving node. Such signals should however be very rare.
Own Id: OTP-18885 Aux Id: GH-7834, GH-7890, PR-7915

Improvements and New Features

Add Windows support for DGRAM socket connect.
Own Id: OTP-18762
process_info/2 now supports lookup of values for specific keys in the process dictionary. For example, {{dictionary, Key}, Value} = process_info(Pid, {dictionary, Key}).
Own Id: OTP-18765 Aux Id: PR-7707
Removed unnecessary regexp library used when generating yielding BIFs.
Own Id: OTP-18830 Aux Id: PR-7823
Fix tty restore when +Bc is used.
Own Id: OTP-18872 Aux Id: GH-7832
Replaced old md5 implementation with an implementation from OpenSSL.
Own Id: OTP-18877
Removed unused makewhatis script.
Own Id: OTP-18899

Erts 14.1.1

Fixed Bugs and Malfunctions

If the external term format encoding of an argument list part of a distributed spawn operation was faulty, the newly spawned remote process could misbehave. The misbehavior included hanging or interpret an incoming message as an argument list to use. This was very unlikely to happen unless using an alternate implementation of the distribution protocol which made a faulty encoding of the argument list. The child process will now detect this error and terminate before executing the user specified code.
Own Id: OTP-18790 Aux Id: PR-7742
Fix bugs where if the body of a matchspec would return a map with a variable ('$1', '$_' etc) as one of the keys or values and the variable was not an immidiate, the term would not be copied to the receiving processes heap. This would later corrupt the term in the table as the GC could place move markers in it, which in turn would cause the VM to crash.
Bug has been present for since OTP 17.0.
Own Id: OTP-18797 Aux Id: PR-7712 GH-7683

Erts 14.1

Fixed Bugs and Malfunctions

maps:put with existing key and identical value was not optimized as a no-op correctly if having the same 32-bit hash as another key in the map. In practice very rare and harmless.
Own Id: OTP-18592
Fixed an issue with truncated crash slogans on failed emulator start.
Own Id: OTP-18623 Aux Id: GH-7344
Fixed a bug where the emulator was unable to determine the current cgroup CPU quota.
Own Id: OTP-18645 Aux Id: GH-7401
A process optimized for parallel signal delivery could under some circumstances lose wakeup information. That is, the processes was not woken up to take care of the signal, so the signal would not be taken care of until the process was woken by another signal. Only processes configured with message_queue_data set to off_heap utilize this optimization.
Own Id: OTP-18647 Aux Id: PR-7595
Function socket:close/1 could cause a VM crash on Windows.
Own Id: OTP-18669 Aux Id: OTP-18029
Fixed a bug in the ARM JIT where it could accidentally add garbage trailing bits when creating bitstrings whose size wasn't an even multiple of 8 bits.
Own Id: OTP-18672 Aux Id: GH-7469
Fix erlang:system_info/1 documentation to show correct types.
Own Id: OTP-18674 Aux Id: PR-7472
Expanded the documentation about how to use the standard_io, standard_error and user I/O devices.
Added the types io:standard_io/0, io:standard:error/0 and io:user/0.
Own Id: OTP-18676 Aux Id: PR-7473 GH-7459
Fix compilation with GNU termcap.
Own Id: OTP-18702 Aux Id: GH-7381
Delivery time of message signals to a process not executing any receive expressions could become very long, potentially infinite. For example, a process checking for messages using process_info(self(), message_queue_len) or process_info(self(), messages) and avoiding to execute a receive expression matching on messages could be very slow in detecting new messages. Note that you are still discouraged from using process_info() this way. A process that wants to check if there are messages available to handle should execute a receive expression matching on messages.
Own Id: OTP-18706 Aux Id: GH-7413, PR-7595, ERIERL-979
On AArch64 (ARM64), when calculating both the quotient and remainder with a divisor begin a power two, the remainder could be incorrectly calculated.
Own Id: OTP-18724 Aux Id: GH-7566, PR-7567
Fix bug causing "magic" references in a compressed ETS table to not keep the referred object alive. The symptom would be the referred object being garbage collected prematurely and the reference appearing stale, not referring to anything. Examples of such magically referred objects are atomics and NIF resources.
Own Id: OTP-18732 Aux Id: GH-7444, PR-7458
Matching out short bitstrings with a fixed size not divisible by 8 could could lead to the runtime system terminating with an "Overrun heap and stack" error.
Own Id: OTP-18733 Aux Id: GH-7292
A constant flow of incoming non-message signals could prevent a process needing to execute dirty from doing so.
Own Id: OTP-18737 Aux Id: PR-7595
A BEAM file usually contains a chunk with the tag "Type" containing type information that can be used by the JIT. The beam_lib:strip/1 takes care to preserve that chunk, but a build/release tool that does customized stripping could accidentally remove the chunk. Loading a BEAM file without the "Type" chunk could cause incorrect behavior of the loaded code.
Own Id: OTP-18745 Aux Id: GH-7492, PR-7616
gen_udp:recv/* for Unix Domain Socket in binary mode and passive mode has been fixed to not crash.
Own Id: OTP-18747 Aux Id: GH-7605
The cleanup operation of not yet delivered signals to a terminated process yielded excessively.
Own Id: OTP-18752 Aux Id: PR-7633
Fixed minor hashing issue with the local option of term_to_binary()/term_to_iovec().
Own Id: OTP-18753 Aux Id: PR-7634

Improvements and New Features

Update gen_tcp_socket and gen_udp_socket to handle 'completion' (socket on Windows).
Own Id: OTP-18586 Aux Id: OTP-18029
Add support for Unix Domain Sockets (only for STREAM sockets) on Windows for 'socket'.
Own Id: OTP-18611 Aux Id: OTP-18029, #5024
In Erlang/OTP 27, by default escripts will be compiled before being executed. That means that the compiler application must be installed. It is possible to force the escript to be interpreted by adding the directive -mode(interpret). to the escript file.
In Erlang/OTP 28, support for interpreting an escript will be removed.
Own Id: OTP-18638
Add basic support for socket ioctl on Windows.
Own Id: OTP-18660
Removed erts/etc/darwin/Info.plist, as it is no longer necessary after macos 10.12
Own Id: OTP-18661 Aux Id: PR-6112
Add support for (Windows) socket option exclusiveaddruse.
Own Id: OTP-18686
[socket] Add support for the 'nopush' option.
Own Id: OTP-18687
Add support for socket option 'BSP STATE'.
Own Id: OTP-18693
Add tcp socket options 'keepcnt', 'keepidle' and 'keepintvl'.
Own Id: OTP-18698
Add support for misc (Windows) socket options ('max_msg_size' and 'maxdg').
Own Id: OTP-18710

Erts 14.0.2

Fixed Bugs and Malfunctions

Fix using the IME (Input Method Editor) to enter text in cmd.exe and powershell.exe on Windows.
Own Id: OTP-18630 Aux Id: PR-7275 GH-7029
Multiple socket:accept calls issue. When making multiple accept calls, only the last call is active.
Own Id: OTP-18635 Aux Id: #7328
Fix the shell to ignore terminal delay when the terminal capabilities report that they should be used.
Own Id: OTP-18636 Aux Id: PR-7352 GH-7308
Fix "oldshell" to echo characters while typing on Windows.
Own Id: OTP-18637 Aux Id: PR-7359 GH-7324
On Windows, a call to the function socket:close, when there are waiting active calls to read, write or accept functions, could hang.
Own Id: OTP-18646
Fix issues when reading or configuring standard_io on Windows when erl.exe is started using -noshell flag.
Own Id: OTP-18649 Aux Id: GH-7261 PR-7400
The following functions are now much faster when given a long list or binary:
- erlang:list_to_integer/1
- erlang:binary_to_integer/1
- erlang:binary_to_integer/2
- erlang:list_to_integer/2
- string:to_integer/1
Own Id: OTP-18659 Aux Id: PR-7426
On AArch64 (ARM64), equality and non-equality tests with literal bitstrings could succeed when they should fail and vice versa.
Own Id: OTP-18663 Aux Id: GH-7433, PR-7437

Erts 14.0.1

Fixed Bugs and Malfunctions

Build of the socket nif failed on Solaris 11.
Own Id: OTP-18585 Aux Id: OTP-18029
Fixed two reduction-counting bugs relating to binaries.
Own Id: OTP-18587
Constructing a binary segment not aligned with a byte boundary, with a size not fitting in 31 bits, and with a value not fitting in a 64-bit word could crash the runtime system.
Own Id: OTP-18597
When a binary construction failed because of bad size for a segment, the error information was not always correct.
Own Id: OTP-18602 Aux Id: GH-7282
Fixed a crash when calling a fun that was defined in a module that had been upgraded.
Own Id: OTP-18621 Aux Id: GH-7288

Erts 14.0

Fixed Bugs and Malfunctions

If a local fun was called while reloading the exact same module that defined said fun, there was a small window in which the call would land in code that was yet to be fully loaded.
Own Id: OTP-18016
Fix the TLS distribution to work when starting Erlang in embedded mode and a connection is done before kernel is fully started.
Own Id: OTP-18248 Aux Id: PR-6227 GH-6085
erl -remsh has been improved to provide better error reasons and work when using a shell without terminal support (that is an "oldshell").
Own Id: OTP-18271 Aux Id: PR-6279
Fix so that -fno-omit-frame-pointer is applied to all of the Erlang VM when using the JIT so that tools, such as perf, can crawl the process stacks.
Own Id: OTP-18274 Aux Id: PR-6048
Compilation server now support unicode paths in compilation server for filesystems that are encoded with unicode.
Own Id: OTP-18277 Aux Id: PR-6306
Reintroduced the optimization that turned anonymous functions without free variables into literals (OTP-15195). This optimization was lost during refactoring in OTP 24.
Alongside this fix, we plan to remove the "fun creator pid" feature in OTP 27. See Upcoming Potential Incompatibilities for more details.
Own Id: OTP-18498
Fixed a crash during tracing on certain platforms that cannot use the machine stack for Erlang code (mainly OpenBSD and Linux with musl).
Own Id: OTP-18561

Improvements and New Features

The enif_set_option() function has been introduced into the NIF API. It can be used in order to set the ERL_NIF_OPT_DELAY_HALT and/or ERL_NIF_OPT_ON_HALT options with which one can synchronize halt of the runtime system with flushing enabled and execution of NIFs. Halt of the runtime system without flushing enabled, now terminates the runtime system without execution of atexit/on_exit handlers that may have been installed into the runtime system which might be considered a potential incompatibility.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-17771 Aux Id: GH-5325, PR-6370
The TTY/terminal subsystem has been rewritten by moving more code to Erlang from the old linked-in driver and implementing all the I/O primitives needed in a NIF instead.
On Unix platforms the user should not notice a lot of difference, besides better handling of unicode characters and fixing of some long standing bugs.
Windows users will notice that erl.exe has the same functionality as a normal Unix shell and that werl.exe has been removed and replaced with a symlink to erl.exe. This makes the Windows Erlang terminal experience identical to that of Unix.
The re-write brings with it a number of bug fixes and feature additions:
- The TTY is now reset when Erlang exits, fixing zsh to not break when terminating an Erlang session.
- standard_error now uses the same unicode mode as standard_io.
- Hitting backspace when searching the shell history with an empty search string no longer breaks the shell.
- Tab expansion now works on remote nodes started using the JCL interface.
- It is now possible to configure the shell slogan and the session slogans (that is the texts that appear when you start an Erlang shell). See the kernel documentation for more details.
- Added shell:start_interactive for starting the interactive shell from a non-interactive Erlang session (for example an escript).
- On Windows, when starting in detached mode the standard handler are now set to nul devices instead of being unset.
- Standard I/O now always defaults to unicode mode if supported. Previously the default was latin1 if the runtime system had been started with -oldshell or -noshell (for example in an escript). To send raw bytes over standard out, one now explicitly has to specify io:setopts(standard_io, [{encoding, latin1}]).
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-17932 Aux Id: PR-6144 GH-3150 GH-3390 GH-4343 GH-4225
Add support for socket on Windows.
- Pre release status.
- Error codes not finalized.
- No explicit support for Windows specific options (socket options, flags for read and write).
- New async api for Windows (completion). See the Asynchronous calls chapter in the (Socket Usage) Users Guide.
- To ensure platform independence, gentcp and gen_udp is _intended to be used (not yet updated).
Own Id: OTP-18029
Updated configure cache for Windows. This makes configure run faster on Windows as many more checks are cached.
Own Id: OTP-18053 Aux Id: PR-6101
Optimized record updates.
Own Id: OTP-18126 Aux Id: PR-6033
Optimized internal hash routines.
Own Id: OTP-18131
As announced when OTP 25 was released, multi time warp mode is now enabled by default. This assumes that all code executing on the system is time warp safe.
If you have old code in the system that is not time warp safe, you now explicitly need to start the system in no time warp mode (or singe time warp mode if it is partially time warp safe) in order to avoid problems. When starting the system in no time warp mode, the system behaves as it did prior to the introduction of the extended time functionality introduced in OTP 18.
If you have code that is not time warp safe, you are strongly encouraged to change this so that you can use multi time warp mode. Compared to no time warp mode, multi time warp mode improves scalability and performance as well as accuracy and precision of time measurements.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-18135 Aux Id: GH-4965, PR-6046
There are several new optimization for binary syntax in the JIT:
- Creation and matching of binaries with segments of fixed sizes have been optimized.
- Creation and matching of UTF-8 segments have been optimized.
- Appending to binaries has been optimized.
Own Id: OTP-18137 Aux Id: PR-6259, PR-6404, PR-6576, PR-6804
As announced since the release of OTP 24, support for:
- version 4 node container types in the external term format are now mandatory. That is, references supporting up to 5 32-bit integer identifiers, and process and port identifiers with support for 64-bit data storage. The distribution flag DFLAG_V4_NC is therefor now also mandatory. OTP has since OTP 24 supported this. Also note that the external format produced by term_to_binary() and term_to_iovec() will unconditionally produce pids, ports, and references supporting this larger format.
- the new link protocol introduced in OTP 23.3 is now mandatory. The distribution flag DFLAG_UNLINK_ID is therefor now also mandatory.
Due to the above, OTP 26 nodes will refuse to connect to OTP nodes from releases prior to OTP 24.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-18140 Aux Id: PR-6072
Optimization of process aliases made possible now that support for version 4 node container types in the external term format is mandatory.
Own Id: OTP-18141 Aux Id: OTP-18140, PR-6073
The compiler and JIT now generate better code for creation of small maps where all keys are literals known at compile time.
Own Id: OTP-18185 Aux Id: GH-6139
When erl -eval fails to execute a command, an error description is printed to standard_error.
Own Id: OTP-18227 Aux Id: PR-6254
Support for UTF-8 atoms and strings in the NIF interface including new functions enif_make_new_atom, enif_make_new_atom_len and enif_get_string_length.
Own Id: OTP-18334 Aux Id: PR-6434
The following inet:setopts/2 options have been introduced:
- reuseport - Reuse of local port. Load balancing may or may not be provided depending on underlying OS.
- reuseport_lb - Reuse of local port. Load balancing provided.
- exclusiveaddruse - Exclusive address/port usage on Windows. This socket option is Windows specific and will silently be ignored on other systems.
The behavior of setting reuseaddr on Windows have changed in a backwards incompatible way. The underlying SO_REUSEADDR socket option is now only set if both the reusaddr and the reuseport inet options have been set. This since the underlying SO_REUSEADDR socket option on Windows behaves similar to how BSD behaves if both the underlying socket options SO_REUSEADDR and SO_REUSEPORT have been set. See the documentation of the reuseaddr option for more information.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-18344 Aux Id: PR-6522, PR-6944, OTP-18324, PR-6481, GH-6461
erlang:display/1 will now print large maps in a more readable way (similar to how small maps are printed).
Own Id: OTP-18360 Aux Id: PR-6497
The BIFs min/2 and max/2 are now allowed to be used in guards and match specs.
Own Id: OTP-18367 Aux Id: GH-6544
Fail enif_init_resource_type and friends by returning NULL if not called during load/upgrade. Old behavior was undefined.
Own Id: OTP-18369
New option include_shared_binaries for the max_heap_size process limit. If set to true, large binaries (> 64 bytes), which may be referred by several processes, are included in the memory sum compared against the max_heap_size limit.
Own Id: OTP-18410 Aux Id: GH-5889, PR-6345
Map comprehensions as suggested in EEP 58 has now been implemented.
Own Id: OTP-18413 Aux Id: EEP-58, PR-6727
Some map operations have been optimized by changing the internal sort order of atom keys. This changes the (undocumented) order of how atom keys in small maps are printed and returned by maps:to_list/1 and maps:next/1. The new order is unpredictable and may change between different invocations of the Erlang VM.
For applications where order is important, there is a new function maps:iterator/2 for creating iterators that return the map elements in a deterministic order. There are also new modifiers k and K for the format string for io:format() to support printing map elements ordered.
Own Id: OTP-18414 Aux Id: PR-6151
Reduced memory usage of file:read_file_info/1,2
Own Id: OTP-18424 Aux Id: PR-6716
Add new function current_stacktrace for trace match specifications used by erlang:trace_pattern/3.
This new option puts the current stacktrace of the caller into the trace message sent to the trace receiver.
Own Id: OTP-18425 Aux Id: PR-6628, GH-5333
The amount of significant bits in node local process identifiers and port identifiers has been extended from 28 bits to 60 bits on 64-bit runtime systems. This makes these identifiers large enough to in practice never having to be reused during the life time of a node.
Own Id: OTP-18435 Aux Id: PR-6827
New trace feature call_memory. Similar to call_time tracing, but instead of measure accumulated time in traced functions it measures accumulated heap space consumed by traced functions. It can be used to compare how much different functions are contributing to garbage collection being triggered.
Own Id: OTP-18440 Aux Id: PR-6351
It is no longer necessary to enable a feature in the runtime system in order to load modules that are using it. It is sufficient to enable the feature in the compiler when compiling it.
That means that to use feature maybe_expr in Erlang/OTP 26, it is sufficient to enable it during compilation.
In Erlang/OTP 27, feature maybe_expr will be enabled by default, but it will be possible to disable it.
Own Id: OTP-18445
Handling of on_load modules during boot has been improved by adding an extra step in the boot order for embedded mode that runs all on_load handlers, instead of relying on explicit invocation of them, later, when the kernel supervision tree starts.
This is mostly a code improvement and OTP internal simplification to avoid future bugs and to simplify code maintenance.
Own Id: OTP-18447
Introduced the local option of term_to_binary/2 and term_to_iovec/2.
Own Id: OTP-18477 Aux Id: PR-7006
Document the commonly used practice to create and store static atoms at NIF load time in callbacks load or upgrade.
Own Id: OTP-18483 Aux Id: PR-6888
Optimize ets:lookup_element for uncompressed tables by using a more efficient method to copy the term from ETS to the heap of the calling process.
Own Id: OTP-18493 Aux Id: PR-6272
The default encoding of atoms by term_to_binary and term_to_iovec have changed from Latin1 to UTF-8. The old encoding can still be obtained with options {minor_version, 1}.
Apart from encoding code points between 128 and 255 with two bytes (UTF-8) instead of one, most atoms will occupy one less byte as the length field use only one byte instead of two if possible.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-18505 Aux Id: PR-6991
The version of zlib included in the Erlang/OTP source code is now 1.2.13.
Own Id: OTP-18517
gen_tcp:send/*, gen_udp:send/* and gen_sctp:send/* have been optimized to use the infamous receive reference optimization, so now sending should not have bad performance when the calling process has a large message queue.
Own Id: OTP-18520 Aux Id: GH-6455
Added the new built-in type dynamic/0 introduced in EEP-61, improving support for gradual type checkers.
Own Id: OTP-18522
Optimize maps:merge/2 memory consumption for small maps (<33 keys) by reusing key tuples or entire maps if the result map has the same number of keys as any of the argument maps.
Own Id: OTP-18523 Aux Id: PR-7004
Optimize maps:merge/2 memory consumption further for small maps by mutating 2nd map to use literal key tuple of 1st map if both have the same keys.
Own Id: OTP-18524 Aux Id: PR-7004, OTP-18523
ceil/1, floor/1, is_bitstring/1, is_boolean/1, is_function/2, and tuple_size/1 can now be used in match specifications.
Own Id: OTP-18526 Aux Id: GH-7045
Allow IPv6 addresses as host in http packets decoded by erlang:decode_packet/3 and gen_tcp packet option. The IPv6 address should be enclosed within [] according to RFC2732.
Own Id: OTP-18540 Aux Id: PR-6900
Removed the experimental erts_alloc_config module. It no longer produced good configurations and cannot be fixed in a reasonably backwards compatible manner. It has since OTP 25 been deprecated and scheduled for removal in OTP 26.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-18549 Aux Id: PR-7105
ERTS internal thread names have been changed. All threads created by ERTS now have a prefix erts_ followed by a type name potentially followed by an integer index. For example, normal schedulers are now named erts_sched_<IX>, dirty CPU schedulers erts_dcpus_<IX>, and dirty IO schedulers erts_dios_<IX>. NIF and driver thread names are truncated at 15 characters regardless of whether the underlying platform support more characters or not.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-18552 Aux Id: PR-6973
Further robustify implementation of large maps (> 32 keys). Keys that happen to have same internal 32-bit hash values are now put in collision nodes which are traversed with linear search. This removes the demand for the internal hash function when salted to eventually produce different hashes for all possible pairs of unequal terms.
Own Id: OTP-18569
In Erlang/OTP 27, 0.0 will no longer be considered to be exactly equal to -0.0. See Upcoming Potential Incompatibilities.
Own Id: OTP-18574

Erts 13.2.2.10

Fixed Bugs and Malfunctions

'DOWN' messages originating from a monitored port, contained the atom process instead of the atom port as the third element when the exit reason was not an immediate term.
Own Id: OTP-19123 Aux Id: GH-8484, PR-8546
When no time warp mode was enabled, a smaller Erlang monotonic time could be read than a previously read time, i.e., breaking the monotonic property. The runtime system will abort when detecting an issue like this since OTP 24.3.4.17 and OTP 25.0.
Up until OTP 25 no time warp mode is the default. As of OTP 26 multi time warp mode is the default.
Own Id: OTP-19147 Aux Id: ERIERL-1043, ERIERL-1106, PR-8619
A scheduler thread could get stuck when deleting a memory allocator carrier when adjacent carriers were deleted and/or inserted simultaneously by other schedulers. This in turn could cause the other schedulers to get stuck as well.
Own Id: OTP-19154 Aux Id: GH-8613, PR-8627

Erts 13.2.2.9

Fixed Bugs and Malfunctions

ETS functions did not properly handle keys containing maps, sometimes matching too many or too few objects.
Own Id: OTP-19070 Aux Id: GH-8385
Fix CPU quota determination for cgroups.
The bug was introduced through OTP-18999.
Own Id: OTP-19071 Aux Id: OTP-18999 PR-8380

Erts 13.2.2.8

Fixed Bugs and Malfunctions

Fixed CPU quota determination for cgroup version 2
Own Id: OTP-18999 Aux Id: GH-7928
Fix faulty reduction counting in exiting process which could cause it to do unnecessary yielding.
Own Id: OTP-19014
Calling erlang:trace/3 with first argument one of ports, processes, existing_ports, existing_processes, existing or all, could cause emulator crash if a dirty scheduler was executing a simultaneous trace action.
Own Id: OTP-19034
Fixed an integer overflow when the monotonic time unit reported by the operating system was greater than 10 and lower than 100 microseconds.
Own Id: OTP-19036 Aux Id: GH-8186
When a traced process executing on a dirty scheduler received an exit signal, the dirty scheduler could use the wrong thread specific data which could lead to a crash.
Own Id: OTP-19043 Aux Id: PR-8342
Fixed a more or less harmless bug that caused time correction of Erlang monotonic time to become slightly off on Windows platforms when QueryPerformanceCounter() was used as OS monotonic time source.
erlang:system_info(os_monotonic_time_source) now also returns information about used resolution which not always corresponds to the resolution of the OS monotonic time source.
Own Id: OTP-19048 Aux Id: PR-8343

Improvements and New Features

Checks for monotonicity of monotonic time have been improved so that Erlang and OS monotonic time are checked separately.
A new configure argument --enable-ensure-os-monotonic-time has also been added. It enables functionality ensuring the monotonicity of monotonic timestamps delivered by the OS. When a non-monotonic timestamp is detected, it will be replaced by the last delivered monotonic timestamp before being used by Erlang's time functionality. Note that you do not want to enable this unless the OS monotonic time source on the system fails to produce monotonic timestamps. This since ensuring the monotonicity of OS monotonic timestamps will hurt scalability and performance of the system.
Own Id: OTP-19044 Aux Id: ERIERL-1043, PR-8342
For severe errors, when the `socket` module terminates the Erlang VM, now an erl_crash.dump is produced, to facilitate post mortem debugging.
Own Id: OTP-19058

Erts 13.2.2.7

Fixed Bugs and Malfunctions

Fix heap corruption bug that could cause runaway memory consumption due to circular offheap list at process exit. Other symptoms may also be possible. Bug exists since OTP 25.0.
Own Id: OTP-18971 Aux Id: GH-8044
The code server could be hanging if a module with on_load function was loaded at the same time as another module was purged using erlang:purge_module directly.
Own Id: OTP-19006
A process optimized for parallel signal delivery could under some circumstances lose wakeup information. That is, the processes was not woken up to take care of the signal, so the signal would not be taken care of until the process was woken by another signal. Only processes configured with message_queue_data set to off_heap utilize this optimization.
Own Id: OTP-19008 Aux Id: GH-8119, PR-8201
Fix bug in re:run/3 where if an invalid UTF-8 subject was given, re:run could get stuck in an infinite loop. Bug was introduced in Erlang/OTP 22.1.
Own Id: OTP-19015 Aux Id: ERIERL-682

Erts 13.2.2.6

Fixed Bugs and Malfunctions

32-bit runtime systems on most Unix like platforms could crash if a BIF timer was set with a huge timeout of more than 68 years into the future. In order for the crash to occur, the huge timer (at a later time than when it was set) had to become the nearest active timer set on the specific scheduler on which it was set. This could not happen on a system with only one scheduler since there would always be shorter timers in the system.
Setting a timer larger than 49 days on Windows could under rare circumstances cause the timeout to be delayed.
Own Id: OTP-18911 Aux Id: ERIERL-1023, PR-7983
Garbage collection of a process on a dirty scheduler could collide with signal handling for that process causing a crash of the runtime system. This bug was introduced in OTP 25.3.2.8 and OTP 26.2.
Own Id: OTP-18957 Aux Id: GH-8051, PR-8088, OTP-18841

Erts 13.2.2.5

Fixed Bugs and Malfunctions

Fix faulty debug assert when page size is larger than 16kb, like on PowerPC. Did crash debug VM directly at start.
Own Id: OTP-18802
A process with message_queue_data configured as off_heap could end up in an inconsistent state when being receive traced, inspected using process_info/2 with the message_queue_len item, or inspected using the break menu (CTRL-C). When it ended up in this inconsistent state, it was not enqueued into a run queue even though it was set in a runnable state.This also effected signals being sent to the process after it had gotten into this inconsistent state, in such a way that it was from this point not possible to communicate with it.
Own Id: OTP-18838 Aux Id: PR-7822, GH-7801
A race occurring when a process was selected for dirty execution simultaneously as it was scheduled for handling a signal could cause the process to end up in an inconsistent state. When it ended up in this inconsistent state, it was not enqueued into a run queue even though it was set in a runnable state. This also effected signals being sent to the process after it had gotten into this inconsistent state, in such a way that it was from this point not possible to communicate with it.
Own Id: OTP-18839 Aux Id: PR-7822, GH-7801
When a process had to to wait in the run queue for a long time before being selected for dirty execution, it could not receive signals. This caused inspection of such a process, for example using process_info/2, to take a long time.
This issue was introduced in OTP 25.3.2.6 and 26.1 when fixing an issue where a constant flow of signals prevented a process from being able to execute dirty.
Own Id: OTP-18841 Aux Id: PR-7822, GH-7801, OTP-18737
Fixed a bug in the JIT that miscompiled large select_val instructions.
Own Id: OTP-18842
On OTP 24 and OTP 25, incoming distributed messages larger than 64 KiB sent using an alias leaked memory if the alias had been removed prior to entering the node. This issue was not present on OTP 26.
Incoming distributed messages larger than 64 KiB sent using an alias which had been removed on the receiving node could crash the node. This crash was quite unlikely on OTP 24 and OTP 25, but very likely on OTP 26.
'DOWN' signals with exit reason larger than 64 KiB directed towards a process on a node with a not matching creation leaked memory on the receiving node. Such signals should however be very rare.
Own Id: OTP-18885 Aux Id: GH-7834, GH-7890, PR-7915
Removed unnecessary PCRE source tar-ball.
Own Id: OTP-18902

Improvements and New Features

Removed unnecessary regexp library used when generating yielding BIFs.
Own Id: OTP-18830 Aux Id: PR-7823
Replaced old md5 implementation with an implementation from OpenSSL.
Own Id: OTP-18877
Removed unused makewhatis script.
Own Id: OTP-18899

Erts 13.2.2.4

Fixed Bugs and Malfunctions

If the external term format encoding of an argument list part of a distributed spawn operation was faulty, the newly spawned remote process could misbehave. The misbehavior included hanging or interpret an incoming message as an argument list to use. This was very unlikely to happen unless using an alternate implementation of the distribution protocol which made a faulty encoding of the argument list. The child process will now detect this error and terminate before executing the user specified code.
Own Id: OTP-18790 Aux Id: PR-7742
On Apple Silicon Macs running macOS Sonoma, the runtime system with the JIT enabled would crash. Therefore, the configure script will by default now disable the JIT on Macs with Apple Silicon. When building for earlier versions of macOS, the JIT can be explicitly enabled by passing --enable-jit to the configure script.
Own Id: OTP-18792 Aux Id: GH-7687
Fix bugs where if the body of a matchspec would return a map with a variable ('$1', '$_' etc) as one of the keys or values and the variable was not an immidiate, the term would not be copied to the receiving processes heap. This would later corrupt the term in the table as the GC could place move markers in it, which in turn would cause the VM to crash.
Bug has been present for since OTP 17.0.
Own Id: OTP-18797 Aux Id: PR-7712 GH-7683

Erts 13.2.2.3

Fixed Bugs and Malfunctions

A process optimized for parallel signal delivery could under some circumstances lose wakeup information. That is, the processes was not woken up to take care of the signal, so the signal would not be taken care of until the process was woken by another signal. Only processes configured with message_queue_data set to off_heap utilize this optimization.
Own Id: OTP-18647 Aux Id: PR-7595
Delivery time of message signals to a process not executing any receive expressions could become very long, potentially infinite. For example, a process checking for messages using process_info(self(), message_queue_len) or process_info(self(), messages) and avoiding to execute a receive expression matching on messages could be very slow in detecting new messages. Note that you are still discouraged from using process_info() this way. A process that wants to check if there are messages available to handle should execute a receive expression matching on messages.
Own Id: OTP-18706 Aux Id: GH-7413, PR-7595, ERIERL-979
Fix bug causing "magic" references in a compressed ETS table to not keep the referred object alive. The symptom would be the referred object being garbage collected prematurely and the reference appearing stale, not referring to anything. Examples of such magically referred objects are atomics and NIF resources.
Own Id: OTP-18732 Aux Id: GH-7444, PR-7458
A constant flow of incoming non-message signals could prevent a process needing to execute dirty from doing so.
Own Id: OTP-18737 Aux Id: PR-7595
The cleanup operation of not yet delivered signals to a terminated process yielded excessively.
Own Id: OTP-18752 Aux Id: PR-7633

Erts 13.2.2.2

Fixed Bugs and Malfunctions

Multiple socket:accept calls issue. When making multiple accept calls, only the last call is active.
Own Id: OTP-18635 Aux Id: #7328
The following functions are now much faster when given a long list or binary:
- erlang:list_to_integer/1
- erlang:binary_to_integer/1
- erlang:binary_to_integer/2
- erlang:list_to_integer/2
- string:to_integer/1
Own Id: OTP-18659 Aux Id: PR-7426

Erts 13.2.2.1

Fixed Bugs and Malfunctions

Fixed a crash during tracing on certain platforms that cannot use the machine stack for Erlang code (mainly OpenBSD and Linux with musl).
Own Id: OTP-18561
Constructing a binary segment not aligned with a byte boundary, with a size not fitting in 31 bits, and with a value not fitting in a 64-bit word could crash the runtime system.
Own Id: OTP-18597

Improvements and New Features

Further robustify implementation of large maps (> 32 keys). Keys that happen to have same internal 32-bit hash values are now put in collision nodes which are traversed with linear search. This removes the demand for the internal hash function when salted to eventually produce different hashes for all possible pairs of unequal terms.
Own Id: OTP-18569

Erts 13.2.2

Fixed Bugs and Malfunctions

If a runtime system which was starting the distribution already had existing pids, ports, or references referring to a node with the same nodename/creation pair that the runtime system was about to use, these already existing pids, ports, or references would not work as expected in various situations after the node had gone alive. This could only occur if the runtime system was communicated such pids, ports, or references prior to the distribution was started. That is, it was extremely unlikely to happen unless the distribution was started dynamically and was even then very unlikely to happen. The runtime system now checks for already existing pids, ports, and references with the same nodename/creation pair that it is about to use. If such are found another creation will be chosen in order to avoid these issues.
Own Id: OTP-18570 Aux Id: PR-7190

Erts 13.2.1

Fixed Bugs and Malfunctions

Fixed a bug in the loader that prevented certain modules compiled with no_ssa_opt from being loaded.
Own Id: OTP-18519 Aux Id: GH-7024
Implementations of the call() driver callback that returned a faulty encoded result could cause a memory leak and could cause invalid data on the heap of the processes calling erlang:port_call/3.
Own Id: OTP-18525 Aux Id: PR-7049
Fixed a memory corruption issue when upgrading code. The bug was introduced in OTP 25.3
Own Id: OTP-18553
Fixed configure tests for a few ARM-specific instructions, which prevented the emulator from being built on some platforms.
Own Id: OTP-18554
Aliases created in combination with a monitor using the {alias, explicit_unalias} option stopped working from remote nodes when a 'DOWN' signal had been received due to the monitor or if the monitor was removed using the erlang:demonitor() BIF.
This bug was introduced in OTP 24.3.4.10 and OTP 25.3.
Own Id: OTP-18557 Aux Id: PR-7131, OTP-18496
In rare circumstances, bit syntax matching of an invalid code point for a utf32 would crash the runtime system.
Own Id: OTP-18560
Building the runtime system failed when native atomic support was missing. Note that execution on such systems have only been rudimentary tested.
Own Id: OTP-18563 Aux Id: GH-7114, PR-7159

Erts 13.2

Fixed Bugs and Malfunctions

Fixed a bug on Windows where file:read_file_info/1 would fail for files with corrupt metadata.
Own Id: OTP-18348 Aux Id: GH-6356
Fix process_info(_, binary) to again include "writable binaries" which were lost in OTP-25.0. Writable binaries are an optimization used when binaries are appended upon in a loop.
Own Id: OTP-18373 Aux Id: PR-6574, GH-6573
Fix rare race when receiving fragmented messages on a terminating connection. Could potentially cause memory leaks as well as double free crashes. Bug exists since OTP 22.0.
Own Id: OTP-18382 Aux Id: PR-6585
Fixed bug that could maybe cause problems when a file descriptor number is closed by a linked in driver and then opened (reused) and passed to enif_select by a NIF. No actual symptoms seen, only failed internal assertions in debug build.
Own Id: OTP-18391
The runtime system could crash when tracing a process executing on a dirty scheduler.
Own Id: OTP-18398 Aux Id: PR-6495, GH-6448, GH-5984
In the binary syntax, attempting to match out integers with size exceeding 2 GiB could crash the runtime system.
Own Id: OTP-18406 Aux Id: GH-6701
Fixed edge case in floating-point negation where A = 0.0, B = -A did not produce B = -0.0 on x86_64 JIT.
Own Id: OTP-18411 Aux Id: GH-6717
Fixed an issue in the JIT that could crash the emulator on some platforms.
Own Id: OTP-18418
Added meta data to the windows installer.
Own Id: OTP-18429 Aux Id: PR-6587 GH-4232 GH-6537
Fixed ETS insertion order into bag and duplicate_bag of tuples with identical keys when passed in a list to ets:insert/2. The insert order has been head-to-tail but was accidentally changed in OTP 23.0. For bag it was reverted (tail-to-head), while for duplicate_bag it was sometimes reverted depending on the length of the list and number of "reductions" left for the calling process.
This fix changes the insert order of ets:insert/2 back to always be head-to-tail of the list argument.
Own Id: OTP-18434 Aux Id: PR-6752
With the JIT for AArch64 (AMD64), calling bxor in with non-integer arguments in a guard would crash the runtime system.
Own Id: OTP-18454 Aux Id: PR-6839
Fix bug regarding process flag max_heap_size. Could cause strange behavior when a process was killed due to exceeding the limit.
Own Id: OTP-18457 Aux Id: PR-6816
Fixed binary comprehensions to be similar to other creation of binary data with respect to its contribution of triggering garbage collection.
Own Id: OTP-18458
In rare circumstances, when a process exceeded its allowed heap size set by option max_heap_size, it would not be killed as it should be, but instead enter a kind of zombie state it would never get out of.
Own Id: OTP-18463 Aux Id: PR-6858
Instead of crashing, the list_to_integer/1 and list_to_integer/2 BIFs now raise the system_limit exception for overlong lists that can't be converted to integers. Similarly, the string:to_integer/1 BIF now returns {error,system_limit} for overlong lists.
Own Id: OTP-18475 Aux Id: PR-6897
Active process aliases of a process at its termination leaked memory.
Own Id: OTP-18496 Aux Id: GH-6947, PR-6953

Improvements and New Features

Support for fully asynchronous distributed signaling where send operations never block. This functionality is by default disabled and can be enabled per process. For more information see the documentation of process_flag(async_dist, Bool).
Own Id: OTP-18374 Aux Id: PR-6632
Added the +JPperf no_fp option to explicitly disable Erlang frame pointers otherwise added when using the +JPperf map option.
Own Id: OTP-18426

Erts 13.1.5

Fixed Bugs and Malfunctions

Comparisons between small numbers and pids or ports would in some edge cases say that the number was greater than the pid or port, violating the term order.
Own Id: OTP-18415
process_info(Pid, status) when Pid /= self() could return an erroneous result.
Own Id: OTP-18421 Aux Id: PR-6806

Erts 13.1.4

Fixed Bugs and Malfunctions

Fixed a bug in selective receive optimization that could crash 32-bit emulators.
Own Id: OTP-18383 Aux Id: ERIERL-905
A race condition which was very rarely triggered could cause the signal queue of a process to become inconsistent causing the runtime system to crash.
Own Id: OTP-18388 Aux Id: OTP-17462, PR-6662

Erts 13.1.3

Fixed Bugs and Malfunctions

Fix perf/gdb JIT symbols to not contain CodeInfoPrologue for the JIT internal module erts_beamasm.
Own Id: OTP-18256 Aux Id: PR-6316
Fixed minor memory leaks.
Own Id: OTP-18281 Aux Id: PR-4840
Fix bugs in ets:insert and ets:insert_new when called with a list of tuples to insert while a concurrent process either deletes or renames the table. The table deletion could be done with ets:delete/1 or be caused by termination of the table owning process.
Symptoms are either VM crash or strange incorrect behavior from the insert operation. The risk of triggering the bugs increases with the length of the list of tuple to insert. Bugs exist since OTP 23.0.
Own Id: OTP-18284 Aux Id: PR-6305
Boost execution of scheduled thread progress jobs. This to prevent memory exhaustion in extremely rapid allocation/deallocation scenarios, such as repeated ETS table creations/deletions.
Own Id: OTP-18294 Aux Id: PR-6390
Fix segv crash during crash dumping an ETS table doing ets:delete_all_objects.
Own Id: OTP-18295
Spec for function net:if_names/0 incorrect
Own Id: OTP-18296 Aux Id: OTP-16464
Fix bug in binary_to_term decoding a binary term 2Gbyte or larger.
Own Id: OTP-18306 Aux Id: GH-6393, PR-6401
Documentation of erlang:module_loaded/1 has been adjusted:
- It did not previously say that the BIF only returns true for modules loaded as current code.
- The warning claiming that the BIF should only be used by the code server has been removed.
Own Id: OTP-18313 Aux Id: PR-6456
Fix list_to_atom/1 for negative code points. Could either return with a positive code point or fail with an incorrect exception.
Own Id: OTP-18321
Fix rare bug causing VM crash when sending to a pid of a spawning process returned from erlang:processes/0.
Only seen when provoked by system process literal_area_collector, triggered by a module purge operation, on a VM started with +Meamin (no customized allocators).
Own Id: OTP-18322 Aux Id: PR-6479
gen_udp:open/2 with option(s) add_membership or drop_membership would drop earlier options.
Own Id: OTP-18323 Aux Id: #6476
The inet:setopts/2 {reuseaddr, true} option will now be ignored on Windows unless the socket is an UDP socket. For more information see the documentation of the reuseaddr option part of the documentation of inet:setopts/2.
Prior to OTP 25 the {reuseaddr, true} option was ignored for all sockets on Windows, but as of OTP 25.0 this was changed so that it was not ignored for any sockets.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-18324 Aux Id: GH-6461, PR-6481
Fix bug in binary_to_term decoding a list of length 1G or longer.
Own Id: OTP-18328 Aux Id: GH-6439, PR-6440
Fix bug in binary_to_term (and distributed receive) when decoding a large map (>32 keys) with unsorted small maps (<= 32) as keys of the large map.
This was only a problem if the term was encoded by erl_interface, jinterface or otherwise, as the VM itself always encodes small maps with sorted keys.
The "binary_to_term" would appear as successful but the created large map was internally inconsistent. The smaller key-maps could not be found with maps:get and friends. Other operations such as map compare and merge could probably also give incorrect results.
Own Id: OTP-18343 Aux Id: GH-6496
Fix Windows bug in open_port({spawn, Command}, ..) when Command is found via the OS search PATH and that directory path contains white spaces. The port program would start but the command line arguments to it could be incorrect.
Own Id: OTP-18345 Aux Id: GH-6387, PR-6396

Erts 13.1.2.1

Fixed Bugs and Malfunctions

Fixed a bug in selective receive optimization that could crash 32-bit emulators.
Own Id: OTP-18383 Aux Id: ERIERL-905
A race condition which was very rarely triggered could cause the signal queue of a process to become inconsistent causing the runtime system to crash.
Own Id: OTP-18388 Aux Id: OTP-17462, PR-6662

Erts 13.1.2

Fixed Bugs and Malfunctions

Add abandon carrier free utilization limit (+Muacful) option to erts_alloc. This option allows the user to mark unused segments in a memory carrier as re-useable by the OS if needed.
This functionality was a non-configurable default before Erlang/OTP 25, but removed due to performance issues.
Own Id: OTP-18290 Aux Id: ERIERL-866 PR-6378

Erts 13.1.1

Fixed Bugs and Malfunctions

Listen sockets created with the socket module, leaked (erlang-) monitors.
Own Id: OTP-18240 Aux Id: #6285
Notifications about available distribution data sent to distribution controller processes could be lost. Distribution controller processes can be used when implementing an alternative distribution carrier. The default distribution over tcp was not effected and the bug was also not present on x86/x86_64 platforms.
Own Id: OTP-18258 Aux Id: GH-6309, PR-6324

Erts 13.1

Fixed Bugs and Malfunctions

Fixed inconsistency bugs in global due to nodeup/nodedown messages not being delivered before/after traffic over connections. Also fixed various other inconsistency bugs and deadlocks in both global_group and global.
As building blocks for these fixes, a new BIF erlang:nodes/2 has been introduced and net_kernel:monitor_nodes/2 has been extended.
The -hidden and -connect_all command line arguments did not work if multiple instances were present on the command line which has been fixed. The new kernel parameter connect_all has also been introduced in order to replace the -connect_all command line argument.
Own Id: OTP-17934 Aux Id: PR-6007
Fixed IPv6 multicast_if and membership socket options.
Own Id: OTP-18091 Aux Id: #5789
Accept funs (NEW_FUN_EXT) with incorrectly encoded size field. This is a workaround for a bug (OTP-18104) existing in OTP 23 and 24 that could cause incorrect size fields in certain cases. The emulator does not use the decoded size field, but erl_interface still does and is not helped by this workaround.
Own Id: OTP-18093 Aux Id: OTP-18104, PR-5987
Fixed issue with inet:getifaddrs hanging on pure IPv6 Windows
Own Id: OTP-18102 Aux Id: #5904
Fix faulty distribution encoding of terms with either
- a fun with bit-string or export-fun in its environment when encoded toward a not yet established (pending) connection
- or a fun with a binary/bitstring, in its environment, referring to an off-heap binary (larger than 64 bytes).
The symptom could be failed decoding on the receiving side leading to aborted connection. Fix OTP-18093 is a workaround for theses bugs that makes the VM accepts such faulty encoded funs.
The first encoding bug toward pending connection exists only in OTP 23 and 24, but the second one exists also on OTP 25.
Own Id: OTP-18104 Aux Id: OTP-18093
Fixed emulator crash that could happen during crashdump generation of ETS tables with options ordered_set and {write_concurrency,true}.
Own Id: OTP-18144 Aux Id: GH-5981
Retrieval of monotonic and system clock resolution on MacOS could cause a crash and/or erroneous results.
Own Id: OTP-18160 Aux Id: PR-6103
Fix bug where the max allowed size of erl +hmax was lower than what was allowed by process_flag.
Own Id: OTP-18161 Aux Id: PR-6081
On computers with ARM64 (AArch64) processors, the JIT could generate incorrect code when more than 4095 bits were skipped at the tail end of a binary match.
Own Id: OTP-18201
In rare circumstances, an is_binary/1 guard test could succeed when given a large integer.
Own Id: OTP-18216 Aux Id: GH-6239, PR-6240
Fix bug causing ets:info (and sometimes ets:whereis) to return 'undefined' for an existing table if a concurrent process were doing ets:insert with a long list on the same table.
Own Id: OTP-18218 Aux Id: ERIERL-855
Fix writing and reading of more than 2 GB in a single read/write operation on macOS. Before this fix attempting to read/write more than 2GB would result in {error,einval}.
Own Id: OTP-18222 Aux Id: PR-6248 GH-6242
Fix bug sometimes causing emulator crash at node shutdown when there are pending connections. Only seen when running duel distribution protocols, inet_drv and inet_tls_dist.
Own Id: OTP-18243 Aux Id: GH-6247, PR-6258

Improvements and New Features

Yield when adjusting large process message queues due to
- copying terms from a literal area prior to removing the literal area.
- changing the message_queue_data state from on_heap to off_heap.
The message queue adjustment work will now be interleaved with all other types of work that processes have to do, even other message queue adjustment work.
Own Id: OTP-17340 Aux Id: PR-6133
Add rudimentary debug feature (option) for the inet-driver based sockets, such as gen_tcp and gen_udp.
Own Id: OTP-18032
Introduced the hidden and dist_listen options to net_kernel:start/2.
Also documented the -dist_listen command line argument which was erroneously documented as a kernel parameter and not as a command line argument.
Own Id: OTP-18107 Aux Id: PR-6009
New documentation chapter "Debugging NIFs and Port Drivers" under Interoperability Tutorial.
Own Id: OTP-18109
Add new API function erl_features:configurable/0
Own Id: OTP-18199 Aux Id: PR-5790

Erts 13.0.4

Fixed Bugs and Malfunctions

The monitor/3 BIF did not apply options to the created monitor if the target process or port did not exist. That is, the corresponding down message would get a `DOWN` tag even if a custom tag had been set, and the returned reference was not an alias even if the alias option had been passed.
Own Id: OTP-18190 Aux Id: GH-6185, PR-6209
The erlang:monotonic_time/1, erlang:system_time/1, erlang:time_offset/1, and os:system_time/1 BIFs erroneously failed when passed the argument native.
Own Id: OTP-18197 Aux Id: GH-6165, PR-6213

Erts 13.0.3

Fixed Bugs and Malfunctions

Distributed exit signals could be lost under the following conditions:
- An exit signal from a parent process to a child process was lost if:
  - the parent process terminated before the spawn request that created the child had completed,
  - the spawn request set up a link between parent and child
  - the spawn request was distributed, and
  - the exit reason was larger than one machine word.
- Loss of a connection over which a not yet completed spawn request was ongoing could cause loss of exit signals. Such loss of exit signals was very rare. Besides the above described connection loss also the following conditions had to be satisfied:
  - The spawn request that was interrupted by the connection loss also had to set up a link between the parent process and the child process.
  - The parent process that issued the spawn request also had to be terminating while the spawn request was interrupted by the connection loss.
  - The same parent process also had to have made other spawn requests to other nodes than to the node to which the connection was lost.
  - These spawn requests to the other nodes also had to set up links.
  - These spawn requests to the other nodes also had to be not yet completed at the time of the connection loss. That is, the spawn reply from the child process had not yet reached the parent process.
  If all the conditions above were met, exit signals to the children spawned due to the above described spawn requests to other nodes could be lost.
  The above bug also caused a significant memory leak when it was triggered since the destruction of the parent process never completed.
Own Id: OTP-18164 Aux Id: PR-6114
A race could cause process_info(Pid, message_queue_len) on other processes to return invalid results.
Own Id: OTP-18169 Aux Id: PR-6134
Fixed reduction counting for handling process system tasks.
Own Id: OTP-18170 Aux Id: PR-6135
Priority elevation of terminating processes did not work which could cause execution of such processes to be delayed.
Own Id: OTP-18175 Aux Id: PR-6142
An unlink operation made by a process that terminated before the unlink operation completed, i.e., before it had received an unlink-ack signal from the linked process, caused an exit signal to erroneously be sent from the terminating process to the process being unlinked. This exit signal would most often be ignored by the receiver, but if the receiver of the exit signal concurrently set up a new link, it could receive the exit signal with the actual exit reason of the terminating process instead of a noproc exit reason. It is however very hard to detect that this has happened and has no obvious negative consequences, so it should be considered harmless.
A distributed unlink-ack signal received by a terminating process was also not properly removed which could cause a minor memory leak.
Own Id: OTP-18177 Aux Id: PR-6150

Erts 13.0.2

Fixed Bugs and Malfunctions

On computers with the ARM64 (AArch64) architecture (such as Apple Silicon Macs) a rem expression followed by a div expression with the same operands could evaluate to the wrong result if the result of the rem expression was unused.
Own Id: OTP-18143

Erts 13.0.1

Fixed Bugs and Malfunctions

A spawn_reply signal from a remote node could be delayed and be delivered after other signals from the newly spawned process.
When this bug triggered, the connection to the node where the process was spawned sometimes could be taken down due to the bug. The following error message would then be logged if this happened: Missing 'spawn_reply' signal from the node <RemoteNode> detected by <Pid> on the node <LocalNode>. The node <RemoteNode> probably suffers from the bug with ticket id OTP-17737.
This bug only affected processes which had enabled off_heap message_queue_data and parallel reception of signals had been automatically enabled.
This bug was introduced in OTP 25.0, ERTS version 13.0.
Own Id: OTP-18105 Aux Id: OTP-16982, PR-6003
Fixed type spec of erlang:system_info(dist_ctrl).
Own Id: OTP-18106 Aux Id: PR-5992
The zlib built in to the runtime system has been updated to version 1.2.12. (Note that on most platforms, the platform's own zlib is used.)
Own Id: OTP-18123 Aux Id: GH-5994
The erlang:is_alive() BIF could return true before configured distribution service was available. This bug was introduced in OTP 25.0 ERTS version 13.0.
The erlang:monitor_node() and erlang:monitor() BIFs could erroneously fail even though configured distribution service was available. This occurred if these BIFs were called after the distribution had been started using dynamic node name assignment but before the name had been assigned.
Own Id: OTP-18124 Aux Id: OTP-17558, PR-6032

Erts 13.0

Fixed Bugs and Malfunctions

The socket option 'reuseaddr' is no longer ignored on Windows.
Own Id: OTP-17447 Aux Id: GH-4819
The growth rate of writable binaries has been adjusted to only increase by 20% after 16MB in size. Before this change the size would always double.
This change may degrade write performance of large binaries.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-17569 Aux Id: PR-4793
Fix reduction counting bug in re:run that caused the function to yield too frequently when doing global matches.
Own Id: OTP-17661 Aux Id: PR-5165
Fix spelling mistakes in epmd error messages.
Own Id: OTP-17758 Aux Id: PR-5391
Fix bug where the "newshell" would trigger a newline at the column width of the terminal, even if the next character to be printed was a newline. This would cause the terminal to render two newlines instead of one.
Own Id: OTP-17779 Aux Id: GH-5403 PR-5599
Fix the memory value returned from ets:info(Tid,memory) when the read_concurrency option is used.
Before this fix the memory used by the scheduler specific lock cache lines was not counted towards the total. This caused the returned memory usage to be very incorrect on systems with many schedulers for tables with man locks.
Own Id: OTP-17832 Aux Id: PR-5494
Fix the undocumented --profile_boot option to work again.
Own Id: OTP-17836 Aux Id: PR-5546
[socket] Encode of sockaddr has been improved.
Own Id: OTP-18020
Fix erl_child_setup (the program used by open_port({spawn,...}) and os:cmd/1) to better handle partial reads from the Erlang VM.
Own Id: OTP-18047 Aux Id: PR-5861
The runtime system would crash when attempting to create more than 33554431 atoms.
Own Id: OTP-18068 Aux Id: GH-5903

Improvements and New Features

Users can now configure ETS tables with the {write_concurrency, auto} option. This option forces tables to automatically change the number of locks that are used at run-time depending on how much concurrency is detected. The {decentralized_counters, true} option is enabled by default when {write_concurrency, auto} is active.
Benchmark results comparing this option with the other ETS optimization options are available here:
https://erlang.org/bench/ets_bench_result_lock_config.html
Own Id: OTP-15991 Aux Id: PR-5208
The net module now works on Windows.
Own Id: OTP-16464
To enable more optimizations, BEAM files compiled with OTP 21 and earlier cannot be loaded in OTP 25.
Own Id: OTP-16702
Optimize minor garbage collection for processes with large number of binaries, funs and/or external pids/ports/refs. This is a continuation of the optimization (OTP-17602) released in OTP-24.1.
Own Id: OTP-16852 Aux Id: ERL-1347, PR-5195
The signal queue of a process with message_queue_data=off_heap* has been optimized to allow parallel reception of signals from multiple processes.
This is possible to do as Erlang only guarantees that signals (i.e., message signals and non-message signals) sent from a single process to another process are ordered in send order. However, there are no ordering guarantees for signals sent from different processes to a particular process. Therefore, several processes can send signals in parallel to a specific process without synchronizing with each other. However, such signal sending was previously always serialized as the senders had to acquire the lock for the outer signal queue of the receiving process. This parallel signal sending optimization yields much better scalability for signal sending than what was previously possible, see https://erlang.org/bench/sigq_bench_result.html for benchmark results.
* Information about how to enable the message_queue_data=off_heap setting can be found in the documentation of the function erlang:process_flag/2.
Own Id: OTP-16982 Aux Id: PR-5020
The JIT now works for 64-bit ARM processors.
Own Id: OTP-17119 Aux Id: PR-4869
Added support for the compile attribute -nifs() to empower compiler and loader with information about which functions may be overridden as NIFs by erlang:load_nif/2. It is recommended to use this attribute in all modules that load NIF libraries.
Own Id: OTP-17151 Aux Id: ERIERL-590, PR-5479
A test case has been added to the otp_SUITE that test that the dependency versions for OTP's applications are correct. The test case uses xref to check if the used functions are available in the specified dependency versions. The test case depends on the Erlang/OTP team's testing infrastructure and will be skipped if its dependencies are not met.
Own Id: OTP-17224
An Erlang installation directory is now relocatable on the file system given that the paths in the installation's RELEASES file are paths that are relative to the installations root directory. The `release_handler:create_RELEASES/4 function can generate a RELEASES file with relative paths if its RootDir parameter is set to the empty string.
Own Id: OTP-17304
The following distribution flags are now mandatory: DFLAG_BIT_BINARIES, DFLAG_EXPORT_PTR_TAG, DFLAG_MAP_TAGS, DFLAG_NEW_FLOATS, and DFLAG_FUN_TAGS. This mainly concerns libraries or application that implement the distribution protocol themselves.
Own Id: OTP-17318 Aux Id: PR-4972
Input for configure scripts adapted to autoconf 2.71.
Own Id: OTP-17414 Aux Id: PR-4967
When binary construction using the binary syntax fails, the error message printed in the shell and by erl_error:format_exception/3,4 will contain more detailed information about what went wrong.
Own Id: OTP-17504 Aux Id: GH-4971, PR-5281, PR-5752
The configuration files .erlang, .erlang.cookie and .erlang.crypt can now be located in the XDG Config Home directory.
See the documentation for each file and filename:basedir/2 for more details.
Own Id: OTP-17554 Aux Id: GH-5016 PR-5408 OTP-17821
Make byte_size/1 and binary_part/2/3 callable from match specs (in ETS and tracing).
Own Id: OTP-17555 Aux Id: PR-5027
Dynamic node name improvements: erlang:is_alive/0 changed to return true for pending dynamic node name and new function net_kernel:get_state/0.
Own Id: OTP-17558 Aux Id: OTP-17538, PR-5111, GH-5402
A new option called short has been added to the functions erlang:float_to_list and erlang:float_to_binary. This option creates the shortest correctly rounded string representation of the given float that can be converted back to the same float again.
Own Id: OTP-17562 Aux Id: GH-4492
The tagged tuple tests and fun-calls have been optimized and are now a little bit cheaper than previously.
These optimizations become possible after making sure that all boxed terms have at least one word allocated after the arity word. This has been accomplished by letting all empty tuples refer to the same empty tuple literal which also reduces memory usage for empty tuples.
Own Id: OTP-17608
The signal queue benchmark in parallel_messages_SUITE and the ETS benchmark in ets_SUITE have benchmark result visualization HTML pages with "fill-screen" buttons to make the graphs bigger. This button did not work as intended before. When pressing the button for a graph, the last graph got replaced with a bigger version and not the one over the button. This is now fixed.
Own Id: OTP-17630
The test case num_bif_SUITE:t_float_to_string previously failed sometimes as it assumed a certain rounding of floats printed with sprintf but the rounding type is platform specific.
Own Id: OTP-17636
Optimize interpreter to create heap binaries of small match contexts if possible.
This optimization was already done in the JIT.
Own Id: OTP-17660 Aux Id: PR-5164
Optimize integer multiplication for x86 JIT
Own Id: OTP-17667 Aux Id: PR-5237
Removed use of node creation value zero as a wildcard. Also prevent zero from being used as creation by erl_interface and jinterface nodes.
Own Id: OTP-17682 Aux Id: PR-5347
Distributed spawn operations now require distributed spawn_request() support. Distributed spawn_request() was introduced in OTP 23. That is, distributed spawn operations against Erlang nodes of releases prior to OTP 23 will fail.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-17683 Aux Id: PR-5306
The Erlang compiler now includes type information in BEAM files, and the JIT can now use that type information to do optimizations such as eliminating or simplifying type tests.
Own Id: OTP-17684 Aux Id: PR-5316, PR-5664
Improved the JIT's support for external tools like perf and gdb, allowing them to show line numbers and even the original Erlang source code when that can be found.
To aid them in finding the source code, the absolute_path compiler option has been added to embed the absolute file path of a module.
Own Id: OTP-17685
Add [32-bit] to the Erlang shell title row for 32-bit VMs.
Own Id: OTP-17717 Aux Id: PR-5290
Instructions for how to build the runtime system for iOS/iPadOS can now be found in HOWTO/INSTALL.md.
Own Id: OTP-17728 Aux Id: PR-5284
Add support for static Elixir NIF modules with non-alphanumeric characters by using new macro STATIC_ERLANG_NIF_LIBNAME.
Own Id: OTP-17729 Aux Id: PR-5477
Add new function caller_line to for trace match specifications used by erlang:trace_pattern/3.
This new option puts the line number of the caller into the trace message sent to the trace receiver.
Own Id: OTP-17753 Aux Id: PR-5305 GH-5297
A new erl command line argument +ssrct has been introduced which will cause the runtime system to skip reading CPU topology information. This reduce start up time especially when the CPU topology is large. Reading of CPU topology information is now also skipped if a user defined CPU topology is set using the +sct command line argument.
Own Id: OTP-17762 Aux Id: GH-5204, PR-5219
The default time warp mode will change in Erlang/OTP 26. Added a warning about this upcoming potential incompatibility to the documentation.
Own Id: OTP-17772 Aux Id: GH-4965 PR-5644
The emulator will no longer mark unused memory as discardable (e.g. through madvise(2)), as it caused more problems than it solved.
Own Id: OTP-17824
When a record matching or record update fails, a {badrecord,ExpectedRecordTag} exception used to be raised. In this release, the exception has been changed to {badrecord,ActualValue}, where ActualValue is the actual that was found instead of the expected record.
Own Id: OTP-17841 Aux Id: PR-5694
Removed the previously undocumented and unsupported emem tool.
Own Id: OTP-17892 Aux Id: PR-5591
Remove version number from the default install path on Windows.
Own Id: OTP-17899 Aux Id: PR-5524
On Windows apply the limit flag JOB_OBJECT_LIMIT_BREAKAWAY_OK in the Erlang service to be able to start a OS child process with a different session number.
Own Id: OTP-17927 Aux Id: PR-5283
New erl command line option +IOs. It can be used to disable scheduler thread poll optimization, which has been seen to cause degraded event latency in some use cases.
Own Id: OTP-17945 Aux Id: GH-4759, PR-5809
An API for multihomed SCTP connect has been added in the guise of gen_sctp:connectx_init/*
Own Id: OTP-17951 Aux Id: PR-5656
[socket] Add encoding of the field hatype of the type sockaddr_ll (family 'packet').
Own Id: OTP-17968 Aux Id: OTP-16464
A cross compilation issue has been fixed about finding libdlpi during the configure phase.
Own Id: OTP-17985 Aux Id: GH-5728
process_info/2 now also accepts parent as argument. When passed, the process identifier of the parent process will be returned.
Own Id: OTP-17999 Aux Id: PR-5768
Add function attributes to erl_nif and erl_driver APis to improve compiler detection of interface misuse.
Own Id: OTP-18006 Aux Id: PR-5932
The exported type erlang:send_destination/0 has been introduced.
Own Id: OTP-18033 Aux Id: PR-2926, GH-5376
Building of the C/C++ make dependencies on Windows has been optimized to be a lot faster.
Own Id: OTP-18036 Aux Id: PR-5846
file:sync/1 will now use the F_BARRIERFSYNC flag when available on Mac OS.
Own Id: OTP-18038

Erts 12.3.2.17

Fixed Bugs and Malfunctions

The code server could be hanging if a module with on_load function was loaded at the same time as another module was purged using erlang:purge_module directly.
Own Id: OTP-19006
Fix bug in re:run/3 where if an invalid UTF-8 subject was given, re:run could get stuck in an infinite loop. Bug was introduced in Erlang/OTP 22.1.
Own Id: OTP-19015 Aux Id: ERIERL-682
Calling erlang:trace/3 with first argument one of ports, processes, existing_ports, existing_processes, existing or all, could cause emulator crash if a dirty scheduler was executing a simultaneous trace action.
Own Id: OTP-19034
Fixed an integer overflow when the monotonic time unit reported by the operating system was greater than 10 and lower than 100 microseconds.
Own Id: OTP-19036 Aux Id: GH-8186
When a traced process executing on a dirty scheduler received an exit signal, the dirty scheduler could use the wrong thread specific data which could lead to a crash.
Own Id: OTP-19043 Aux Id: PR-8342
Fixed a more or less harmless bug that caused time correction of Erlang monotonic time to become slightly off on Windows platforms when QueryPerformanceCounter() was used as OS monotonic time source.
erlang:system_info(os_monotonic_time_source) now also returns information about used resolution which not always corresponds to the resolution of the OS monotonic time source.
Own Id: OTP-19048 Aux Id: PR-8343

Improvements and New Features

Checks for monotonicity of monotonic time have been improved so that Erlang and OS monotonic time are checked separately.
A new configure argument --enable-ensure-os-monotonic-time has also been added. It enables functionality ensuring the monotonicity of monotonic timestamps delivered by the OS. When a non-monotonic timestamp is detected, it will be replaced by the last delivered monotonic timestamp before being used by Erlang's time functionality. Note that you do not want to enable this unless the OS monotonic time source on the system fails to produce monotonic timestamps. This since ensuring the monotonicity of OS monotonic timestamps will hurt scalability and performance of the system.
Own Id: OTP-19044 Aux Id: ERIERL-1043, PR-8342

Erts 12.3.2.16

Fixed Bugs and Malfunctions

32-bit runtime systems on most Unix like platforms could crash if a BIF timer was set with a huge timeout of more than 68 years into the future. In order for the crash to occur, the huge timer (at a later time than when it was set) had to become the nearest active timer set on the specific scheduler on which it was set. This could not happen on a system with only one scheduler since there would always be shorter timers in the system.
Setting a timer larger than 49 days on Windows could under rare circumstances cause the timeout to be delayed.
Own Id: OTP-18911 Aux Id: ERIERL-1023, PR-7983

Erts 12.3.2.15

Fixed Bugs and Malfunctions

Fix faulty debug assert when page size is larger than 16kb, like on PowerPC. Did crash debug VM directly at start.
Own Id: OTP-18802
On OTP 24 and OTP 25, incoming distributed messages larger than 64 KiB sent using an alias leaked memory if the alias had been removed prior to entering the node. This issue was not present on OTP 26.
Incoming distributed messages larger than 64 KiB sent using an alias which had been removed on the receiving node could crash the node. This crash was quite unlikely on OTP 24 and OTP 25, but very likely on OTP 26.
'DOWN' signals with exit reason larger than 64 KiB directed towards a process on a node with a not matching creation leaked memory on the receiving node. Such signals should however be very rare.
Own Id: OTP-18885 Aux Id: GH-7834, GH-7890, PR-7915
Removed unnecessary PCRE source tar-ball.
Own Id: OTP-18902

Improvements and New Features

Removed unnecessary regexp library used when generating yielding BIFs.
Own Id: OTP-18830 Aux Id: PR-7823
Replaced old md5 implementation with an implementation from OpenSSL.
Own Id: OTP-18877
Removed unused makewhatis script.
Own Id: OTP-18899

Erts 12.3.2.14

Fixed Bugs and Malfunctions

Fix bug causing "magic" references in a compressed ETS table to not keep the referred object alive. The symptom would be the referred object being garbage collected prematurely and the reference appearing stale, not referring to anything. Examples of such magically referred objects are atomics and NIF resources.
Own Id: OTP-18732 Aux Id: GH-7444, PR-7458
The cleanup operation of not yet delivered signals to a terminated process yielded excessively.
Own Id: OTP-18752 Aux Id: PR-7633
If the external term format encoding of an argument list part of a distributed spawn operation was faulty, the newly spawned remote process could misbehave. The misbehavior included hanging or interpret an incoming message as an argument list to use. This was very unlikely to happen unless using an alternate implementation of the distribution protocol which made a faulty encoding of the argument list. The child process will now detect this error and terminate before executing the user specified code.
Own Id: OTP-18790 Aux Id: PR-7742
Fix bugs where if the body of a matchspec would return a map with a variable ('$1', '$_' etc) as one of the keys or values and the variable was not an immidiate, the term would not be copied to the receiving processes heap. This would later corrupt the term in the table as the GC could place move markers in it, which in turn would cause the VM to crash.
Bug has been present for since OTP 17.0.
Own Id: OTP-18797 Aux Id: PR-7712 GH-7683

Erts 12.3.2.13

Fixed Bugs and Malfunctions

The following functions are now much faster when given a long list or binary:
- erlang:list_to_integer/1
- erlang:binary_to_integer/1
- erlang:binary_to_integer/2
- erlang:list_to_integer/2
- string:to_integer/1
Own Id: OTP-18659 Aux Id: PR-7426

Erts 12.3.2.12

Fixed Bugs and Malfunctions

In rare circumstances, bit syntax matching of an invalid code point for a utf32 would crash the runtime system.
Own Id: OTP-18560
If a runtime system which was starting the distribution already had existing pids, ports, or references referring to a node with the same nodename/creation pair that the runtime system was about to use, these already existing pids, ports, or references would not work as expected in various situations after the node had gone alive. This could only occur if the runtime system was communicated such pids, ports, or references prior to the distribution was started. That is, it was extremely unlikely to happen unless the distribution was started dynamically and was even then very unlikely to happen. The runtime system now checks for already existing pids, ports, and references with the same nodename/creation pair that it is about to use. If such are found another creation will be chosen in order to avoid these issues.
Own Id: OTP-18570 Aux Id: PR-7190
Constructing a binary segment not aligned with a byte boundary, with a size not fitting in 31 bits, and with a value not fitting in a 64-bit word could crash the runtime system.
Own Id: OTP-18597

Improvements and New Features

Further robustify implementation of large maps (> 32 keys). Keys that happen to have same internal 32-bit hash values are now put in collision nodes which are traversed with linear search. This removes the demand for the internal hash function when salted to eventually produce different hashes for all possible pairs of unequal terms.
Own Id: OTP-18569

Erts 12.3.2.11

Fixed Bugs and Malfunctions

Fix bug sometimes causing emulator crash at node shutdown when there are pending connections. Only seen when running duel distribution protocols, inet_drv and inet_tls_dist.
Own Id: OTP-18243 Aux Id: GH-6247, PR-6258
Fix bug in binary_to_term (and distributed receive) when decoding a large map (>32 keys) with unsorted small maps (<= 32) as keys of the large map.
This was only a problem if the term was encoded by erl_interface, jinterface or otherwise, as the VM itself always encodes small maps with sorted keys.
The "binary_to_term" would appear as successful but the created large map was internally inconsistent. The smaller key-maps could not be found with maps:get and friends. Other operations such as map compare and merge could probably also give incorrect results.
Own Id: OTP-18343 Aux Id: GH-6496
Implementations of the call() driver callback that returned a faulty encoded result could cause a memory leak and could cause invalid data on the heap of the processes calling erlang:port_call/3.
Own Id: OTP-18525 Aux Id: PR-7049
Aliases created in combination with a monitor using the {alias, explicit_unalias} option stopped working from remote nodes when a 'DOWN' signal had been received due to the monitor or if the monitor was removed using the erlang:demonitor() BIF.
This bug was introduced in OTP 24.3.4.10 and OTP 25.3.
Own Id: OTP-18557 Aux Id: PR-7131, OTP-18496

Erts 12.3.2.10

Fixed Bugs and Malfunctions

Active process aliases of a process at its termination leaked memory.
Own Id: OTP-18496 Aux Id: GH-6947, PR-6953

Erts 12.3.2.9

Fixed Bugs and Malfunctions

process_info(Pid, status) when Pid /= self() could return an erroneous result.
Own Id: OTP-18421 Aux Id: PR-6806
In rare circumstances, when a process exceeded its allowed heap size set by option max_heap_size, it would not be killed as it should be, but instead enter a kind of zombie state it would never get out of.
Own Id: OTP-18463 Aux Id: PR-6858

Erts 12.3.2.8

Fixed Bugs and Malfunctions

Fixed a bug in selective receive optimization that could crash 32-bit emulators.
Own Id: OTP-18383 Aux Id: ERIERL-905
A race condition which was very rarely triggered could cause the signal queue of a process to become inconsistent causing the runtime system to crash.
Own Id: OTP-18388 Aux Id: OTP-17462, PR-6662

Erts 12.3.2.7

Fixed Bugs and Malfunctions

Spec for function net:if_names/0 incorrect
Own Id: OTP-18296 Aux Id: OTP-16464
Fix bug in binary_to_term decoding a binary term 2Gbyte or larger.
Own Id: OTP-18306 Aux Id: GH-6393, PR-6401
Fix list_to_atom/1 for negative code points. Could either return with a positive code point or fail with an incorrect exception.
Own Id: OTP-18321
Fix bug in binary_to_term decoding a list of length 1G or longer.
Own Id: OTP-18328 Aux Id: GH-6439, PR-6440

Erts 12.3.2.6

Fixed Bugs and Malfunctions

Notifications about available distribution data sent to distribution controller processes could be lost. Distribution controller processes can be used when implementing an alternative distribution carrier. The default distribution over tcp was not effected and the bug was also not present on x86/x86_64 platforms.
Own Id: OTP-18258 Aux Id: GH-6309, PR-6324

Erts 12.3.2.5

Fixed Bugs and Malfunctions

Fix writing and reading of more than 2 GB in a single read/write operation on macOS. Before this fix attempting to read/write more than 2GB would result in {error,einval}.
Own Id: OTP-18222 Aux Id: PR-6248 GH-6242

Erts 12.3.2.4

Fixed Bugs and Malfunctions

Fix bug causing ets:info (and sometimes ets:whereis) to return 'undefined' for an existing table if a concurrent process were doing ets:insert with a long list on the same table.
Own Id: OTP-18218 Aux Id: ERIERL-855

Erts 12.3.2.3

Fixed Bugs and Malfunctions

Fix faulty distribution encoding of terms with either
- a fun with bit-string or export-fun in its environment when encoded toward a not yet established (pending) connection
- or a fun with a binary/bitstring, in its environment, referring to an off-heap binary (larger than 64 bytes).
The symptom could be failed decoding on the receiving side leading to aborted connection. Fix OTP-18093 is a workaround for theses bugs that makes the VM accepts such faulty encoded funs.
The first encoding bug toward pending connection exists only in OTP 23 and 24, but the second one exists also on OTP 25.
Own Id: OTP-18104 Aux Id: OTP-18093
Distributed exit signals could be lost under the following conditions:
- An exit signal from a parent process to a child process was lost if:
  - the parent process terminated before the spawn request that created the child had completed,
  - the spawn request set up a link between parent and child
  - the spawn request was distributed, and
  - the exit reason was larger than one machine word.
- Loss of a connection over which a not yet completed spawn request was ongoing could cause loss of exit signals. Such loss of exit signals was very rare. Besides the above described connection loss also the following conditions had to be satisfied:
  - The spawn request that was interrupted by the connection loss also had to set up a link between the parent process and the child process.
  - The parent process that issued the spawn request also had to be terminating while the spawn request was interrupted by the connection loss.
  - The same parent process also had to have made other spawn requests to other nodes than to the node to which the connection was lost.
  - These spawn requests to the other nodes also had to set up links.
  - These spawn requests to the other nodes also had to be not yet completed at the time of the connection loss. That is, the spawn reply from the child process had not yet reached the parent process.
  If all the conditions above were met, exit signals to the children spawned due to the above described spawn requests to other nodes could be lost.
  The above bug also caused a significant memory leak when it was triggered since the destruction of the parent process never completed.
Own Id: OTP-18164 Aux Id: PR-6114
A race could cause process_info(Pid, message_queue_len) on other processes to return invalid results.
Own Id: OTP-18169 Aux Id: PR-6134
Fixed reduction counting for handling process system tasks.
Own Id: OTP-18170 Aux Id: PR-6135
Priority elevation of terminating processes did not work which could cause execution of such processes to be delayed.
Own Id: OTP-18175 Aux Id: PR-6142
An unlink operation made by a process that terminated before the unlink operation completed, i.e., before it had received an unlink-ack signal from the linked process, caused an exit signal to erroneously be sent from the terminating process to the process being unlinked. This exit signal would most often be ignored by the receiver, but if the receiver of the exit signal concurrently set up a new link, it could receive the exit signal with the actual exit reason of the terminating process instead of a noproc exit reason. It is however very hard to detect that this has happened and has no obvious negative consequences, so it should be considered harmless.
A distributed unlink-ack signal received by a terminating process was also not properly removed which could cause a minor memory leak.
Own Id: OTP-18177 Aux Id: PR-6150
The monitor/3 BIF did not apply options to the created monitor if the target process or port did not exist. That is, the corresponding down message would get a `DOWN` tag even if a custom tag had been set, and the returned reference was not an alias even if the alias option had been passed.
Own Id: OTP-18190 Aux Id: GH-6185, PR-6209
The erlang:monotonic_time/1, erlang:system_time/1, erlang:time_offset/1, and os:system_time/1 BIFs erroneously failed when passed the argument native.
Own Id: OTP-18197 Aux Id: GH-6165, PR-6213

Erts 12.3.2.2

Fixed Bugs and Malfunctions

Fixed emulator crash that could happen during crashdump generation of ETS tables with options ordered_set and {write_concurrency,true}.
Own Id: OTP-18144 Aux Id: GH-5981

Erts 12.3.2.1

Fixed Bugs and Malfunctions

Accept funs (NEW_FUN_EXT) with incorrectly encoded size field. This is a workaround for a bug (OTP-18104) existing in OTP 23 and 24 that could cause incorrect size fields in certain cases. The emulator does not use the decoded size field, but erl_interface still does and is not helped by this workaround.
Own Id: OTP-18093 Aux Id: OTP-18104, PR-5987
The zlib built in to the runtime system has been updated to version 1.2.12. (Note that on most platforms, the platform's own zlib is used.)
Own Id: OTP-18123 Aux Id: GH-5994

Erts 12.3.2

Fixed Bugs and Malfunctions

Let EPMD tolerate failure when binding to IPv4/IPv6 loopback intefaces in addition to user-supplied addresses via ERL_EPMD_ADDRESS or the -address option. This can happen, for example, if the host system has ipv6 disabled via the disable_ipv6 sysctl.
Own Id: OTP-17970 Aux Id: PR-5762
Fixed a rare bug in binary_to_term/1, enif_make_map_from_arrays, erl_drv_send_term, and Erlang distribution that could crash the emulator.
Own Id: OTP-18027
Fixed a rare race in persistent_term:get/1,2 that could cause it to return the value of another key.
Own Id: OTP-18065 Aux Id: GH-5908
Fix bug where the process message queue was left in an inconsistent state when changing from on_heap to off_heap message queue data causing the GC to segfault.
Own Id: OTP-18075 Aux Id: PR-5927
Fix functions that convert universal to localtime (such as erlang:localtime/0 and erlang:universaltime_to_localtime/1) to fetch the correct localtime if it is changed after the start of the VM.
Own Id: OTP-18076 Aux Id: ERIERL-802 PR-5905
Fix memory leak when a process doing a distributed fragmented send is sent an exit signal. Before this fix the receiving node would be left with an incomplete message that would remain until the nodes were disconnected. The bug has existed since Erlang/OTP 21.
Own Id: OTP-18077 Aux Id: GH-5876 PR-5892
Corrected the behaviour of the shutdown function when using with the inet_backend = socket. It was not sufficiently compatible with the "old" gen_tcp.
Own Id: OTP-18080 Aux Id: GH-5930

Erts 12.3.1

Fixed Bugs and Malfunctions

erlang:open_port({spawn, _},_) has been fixed on Windows to handle whitespace characters in the path correctly.
This could, for example, cause execution of the resolver helper program inet_gethost to fail and instead possibly execute a different program.
Own Id: OTP-17978 Aux Id: OTP-17958
Fix race condition when creating crash dump that could cause multiple threads to race when writing the initial information in a crash dump.
The race condition was introduced in erts-12.2 (Erlang/OTP 24.2).
Own Id: OTP-17993 Aux Id: PR-5806
Fix Erlang monotonic time on MacOS. Previously used OS monotonic time primitive on MacOS is buggy and will not be used anymore. It has been replaced with usage of another OS monotonic time primitive that does not appear to be buggy.
Own Id: OTP-17998 Aux Id: PR-5825, GH-5554

Erts 12.3

Fixed Bugs and Malfunctions

Fixed a bug in the x86 JIT that might cause floating point instructions to wrongly throw an exception.
Own Id: OTP-17822
Preserve correct nodedown_reason if supervised distribution controller processes exit with {shutdown, Reason}.
Own Id: OTP-17838 Aux Id: PR-5748
Handling of send_timeout for gen_tcp has been corrected so that the timeout is honored also when sending 0 bytes.
Own Id: OTP-17840
By default global does not take any actions to restore a fully connected network when connections are lost due to network issues. This is problematic for all applications expecting a fully connected network to be provided, such as for example mnesia, but also for global itself. A network of overlapping partitions might cause the internal state of global to become inconsistent. Such an inconsistency can remain even after such partitions have been brought together to form a fully connected network again. The effect on other applications that expects that a fully connected network is maintained may vary, but they might misbehave in very subtle hard to detect ways during such a partitioning.
In order to prevent such issues, we have introduced a prevent overlapping partitions fix which can be enabled using the prevent_overlapping_partitions kernel(6) parameter. When this fix has been enabled, global will actively disconnect from nodes that reports that they have lost connections to other nodes. This will cause fully connected partitions to form instead of leaving the network in a state with overlapping partitions. Note that this fix has to be enabled on all nodes in the network in order to work properly. Since this quite substantially changes the behavior, this fix is currently disabled by default. Since you might get hard to detect issues without this fix you are, however, strongly advised to enable this fix in order to avoid issues such as the ones described above. As of OTP 25 this fix will become enabled by default.
Own Id: OTP-17843 Aux Id: ERIERL-732, PR-5611
Corrected the type specification of erlang:seq_trace/2.
Own Id: OTP-17900 Aux Id: GH-5667
Fix memory leak when tracing on running on a process that only handle system tasks or non-message signals (for example process_info requests).
Own Id: OTP-17904 Aux Id: ERIERL-757

Improvements and New Features

Add support for using socket:sockaddr_in() and socket:sockaddr_in6() when using gen_sctp, gen_tcp and gen_udp. This will make it possible to use Link Local IPv6 addresses.
Own Id: OTP-17455 Aux Id: GH-4852
Show on_load failure reasons in embedded mode.
Own Id: OTP-17718 Aux Id: PR-5199
Compile date saved in the Erlang VM executable has been removed.
Own Id: OTP-17891 Aux Id: PR-5589
Improve documentation for the dynamic node name feature.
Own Id: OTP-17918

Erts 12.2.1

Fixed Bugs and Malfunctions

Fixed a memory leak in file:read_file_info/2 and file:read_file/1 on Windows.
Own Id: OTP-17827 Aux Id: GH-5527
Fix GC emulator crash when spawn_request was used when message tracing was enabled.
Own Id: OTP-17871 Aux Id: PR-5612

Erts 12.2

Fixed Bugs and Malfunctions

When matching and constructing utf16 segments in the binary syntax, the native flag would be ignored. That is, the endian would always be big endian even on a little-endian computer (almost all modern computers).
Own Id: OTP-17713
Fix the help printout of +JPperf.
Own Id: OTP-17749 Aux Id: PR-5378 GH-5361
Fix bug that could cause Erlang to deadlock during creation of an Erlang crash dump.
Own Id: OTP-17751 Aux Id: PR-5315
Fixed C++ build errors on some aarch64 platforms.
Own Id: OTP-17763 Aux Id: GH-5351
For macOS, the Info.plist file embedded in the runtime system now only contains the absolute minimum amount of information needed for the web view in wx to work towards localhost. The other fields have been removed, allowing an application packaged in a bundle to specify the application name and other parameter in its own Info.plist file.
Own Id: OTP-17785 Aux Id: PR-5393
Fix bug in internal stacks (WSTACK and ESTACK) used by term_to_binary/2 to encode terms. The bug could cause a segfault if a very very large map was to be encoded with the deterministic option given.
Own Id: OTP-17804 Aux Id: PR-5372
Improve the error printout when open_port/2 fails because of invalid arguments.
Own Id: OTP-17805 Aux Id: PR-5406
Fix bug in crash dumps where the stackframe of a process would be printed using an incorrect format.
Crash dump viewer has also been fixed to be able read the broken stack format.
The bug has existed since Erlang/OTP 23.0.
Own Id: OTP-17814 Aux Id: PR-5462

Improvements and New Features

An option for enabling dirty scheduler specific allocator instances has been introduced. By default such allocator instances are disabled. For more information see the documentation of the +Mdai erl command line argument.
Own Id: OTP-17363 Aux Id: GH-4728, PR-5187
Minor optimization of receive markers in message queues.
Own Id: OTP-17673 Aux Id: OTP-16226
All predefined types have been added to the erlang module together with documentation.
Any reference to a predefined type now links to that documentation so that the user can view it.
Own Id: OTP-17689 Aux Id: PR-5292
Suppress a code checker warning caused by debug builds of YCF. YCF tries to get a conservative estimate of the bottom of the stack by reading and returning a call stack allocated variable.
Own Id: OTP-17719
Add file and product properties to erl.exe and werl.exe.
Own Id: OTP-17724 Aux Id: ERL-1224
Micro optimization in bitstring append operations.
Own Id: OTP-17760 Aux Id: ERIERL-725, PR-5414
Responsiveness of processes executing on normal or low priority could suffer due to code purging or literal area removal on systems with a huge amount of processes. This since during these operations all processes on the system were scheduled for execution at once.
This problem has been fixed by introducing a limit on outstanding purge and copy literal requests in the system. By default this limit is set to twice the amount of schedulers on the system. This will ensure that schedulers will have enough work scheduled to perform these operations as quickly as possible at the same time as other work will be interleaved to a much higher degree. Performance of these operations will however be somewhat degraded due to the overhead of enforcing this limit compared to when using a very large limit.
This limit can be set by passing the +zosrl command line argument to erl, or by calling erlang:system_flag(outstanding_system_requests_limit, NewLimit).
Own Id: OTP-17796 Aux Id: ERIERL-729, PR-5473

Erts 12.1.5

Fixed Bugs and Malfunctions

The runtime system could call select() with a too large timeout value when executing on MacOS. This could in turn cause the runtime system to crash.
Own Id: OTP-17735 Aux Id: GH-5339
The fix for Linux's behaviour when reconnecting an UDP socket in PR-5120 released in OTP-24.1.2 has been refined to only dissolve the socket's connection before a connect if the socket is already connected, that is: only for a reconnect.
This allows code to open a socket with an ephemeral port, get the port number and connect; without the port number changing (on Linux). This turned out to have at least one valid use case (besides test cases).
Should one reconnect the socket then the port number may change, on Linux; it is a known quirk, which can be worked around by binding to a specific port number when opening the socket. If you can do without an ephemeral port, that is...
Own Id: OTP-17736 Aux Id: GH-5279, PR-5120, OTP-17559
Certain distributed signals that for various reasons must to be forced into the distribution buffer even when it is full would instead be lost if the distribution buffer was full when sent. The effected signals:
- EXIT signals with exit reasons of one word size.
- DOWN signals with exit reasons of one word size.
- demonitor signals from a terminating process.
- unlink_ack signals on OTP 23 and 24.
- spawn_reply signals on OTP 23 and 24.
Own Id: OTP-17737 Aux Id: GH-5346, GH-4989

Erts 12.1.4

Fixed Bugs and Malfunctions

Fix bug where a gen_tcp write error that happened during a delayed_send would cause a use after free segfault.
Own Id: OTP-17731 Aux Id: PR-5285
Fix x86 JIT bug where a rem instruction could cause a segfault if given values that would cause an badarith exception.
Own Id: OTP-17732 Aux Id: PR-5331 ERIERL-664

Erts 12.1.3

Fixed Bugs and Malfunctions

Reduction counter was not updated before and after doing apply operations on the runtime system with the jit enabled. This caused reduction counting to get out of sync if a garbage collection was made as part of the apply operation.
Own Id: OTP-17675
This fixes a bug in erts_factory_undo that caused the heap to not be reset correctly. The erts_factory_undo function is, for example, called when a binary_to_term/1 call fails to reset the heap to its state before the binary_to_term/1 call. This can cause the heap to contain invalid terms which potentially can cause issues (e.g., crashes) when the whole heap is scanned.
Own Id: OTP-17677
When attempting to construct a binary with an segment having an illegal type for the size (e.g. an atom), there could be an unnecessary memory allocation (and subsequent deallocation) before the operation failed. Amended to fail before allocating any memory for the binary.
Own Id: OTP-17686
Fix bug in persistent_term when a key-value pair contains a magic reference that is referred more than once. Magic references are NIF resources or returned from BIFs like ets:new, atomics:new. The bug could cause the memory of the referred resource to be prematurely deallocated.
The bug also apply to magic references in message passing on a runtime built with configure option --enable-sharing-preserving.
Bug exist for 64-bit since OTP-24.0 and for 32-bit since OTP-20.0.
Own Id: OTP-17700 Aux Id: GH-5271, PR-5273
Fixed a crash when inspecting the stack trace of an exception raised at a very high line number.
This bug was introduced in OTP 24.
Own Id: OTP-17712
The following two bugs that caused erlang:demonitor() to behave erroneously have been fixed. The bugs were only triggered if the monitor that was removed by demonitor() had previously been created simultaneously as a monitor and as an alias.
- A demonitor operation on a monitor created using the {alias, reply_demonitor} option erroneously behaved as if the {alias, explicit_unalias} option had been used.
- A demonitor operation did not prevent a corresponding 'DOWN' message from being delivered if the monitor reference was kept as an active alias after the operation. This could only occur if the monitored process simultaneously terminated before the demonitor signal reached it, and the exit reason was not an immediate term. That is, a term larger than one machine word.
Own Id: OTP-17722 Aux Id: GH-5310, PR-5313

Erts 12.1.2

Improvements and New Features

The python scripts that existed in erts/lib_src/yielding_c_fun/lib/tiny_regex_c/scripts had a license that was incompatible with Erlang/OTP's license. This ticket removes these scripts that were not used by us.
Own Id: OTP-17658

Erts 12.1.1

Fixed Bugs and Malfunctions

A race between an exiting port and handling of simultaneously received signals to that port could cause a runtime system crash. The effected signals are link, monitor and demonitor. On OTP 22 a similar race could also cause a memory leak when receiving an unlink signal.
Own Id: OTP-17642 Aux Id: PR-5248
A user defined tag on a monitor message could cause the runtime system to crash when the monitor message had been received.
Own Id: OTP-17646 Aux Id: GH-5221, PR-5232
A call to erlang:demonitor(Ref) where the reference Ref referred to an active alias, but not an active monitor, caused the runtime system to crash.
Own Id: OTP-17647 Aux Id: GH-5225, PR-5230
The message queue of a process entered an inconsistent state after a receive expression with an invalid timeout value was executed. If the exception raised due to the invalid timeout value was caught, the following receive expression executed by the process could fail to match messages already present in the message queue.
On OTP 24 this could also cause the whole runtime system to crash.
Own Id: OTP-17651 Aux Id: GH-5235, PR-5244
Sending a Port ! {PortOwner, close} signal from a process other than the port owner could erroneously trigger a badsig exit signal being sent to the port owner process even though the correct PortOwner had been passed in the signal.
Own Id: OTP-17665 Aux Id: PR-5248

Erts 12.1

Fixed Bugs and Malfunctions

Atoms with Unicode code points greater than 255 (for example Greek or Cyrillic characters) would not be displayed correctly by crashdump_viewer.
Own Id: OTP-17377
Fix rare minor memory leak related to jit code loading.
Own Id: OTP-17445 Aux Id: PR-4843
The extended error information has been corrected and improved for the following BIFs: binary_to_existing_atom/2, list_to_existing_atom/1, erlang:send_after/{3,4}, and erlang:start_timer/{3,4}.
Own Id: OTP-17449 Aux Id: GH-4900
Fix bug provoked when building with gcc 10 and link time optimization (-flto), causing Erlang compiler to crash. Bug exists since OTP-24.0.
Own Id: OTP-17477 Aux Id: GH-4846, PR-4894
Corrected bugs where builds were not reducible even when the deterministic option was given. In particular, modules with map literals with more than 32 elements could cause this problem.
As part of this fix, the term_to_binary BIF now accepts the option deterministic.
Own Id: OTP-17495 Aux Id: PR-5153
After an exception has been caught in a process, the stack trace would be kept in the process longer than necessary.
Own Id: OTP-17512
Fix rare race bug in memory management of distribution entries. Have been seen to cause VM crash when massive number of repeated concurrent failing connection attempts.
Own Id: OTP-17513 Aux Id: GH-4964, PR-5015
The configure test for --disable-esock-socket-registry has been corrected so disabling now works.
Own Id: OTP-17539
init:stop() no longer unloads loaded code before terminating the runtime system. On systems with slow CPUs (such as Raspberry PI Zero), that can significantly speed up termination of the runtime system.
Own Id: OTP-17542 Aux Id: GH-5031, PR-5032
Fixed match specifications that use maps in either the guard or the body to work properly.
With this fix both keys and values in maps can be expressions.
Various other crashes and bugs when using maps in match specifications have also been fixed.
Own Id: OTP-17567 Aux Id: PR-4915 PR-5115
Parsing of the result value in the native DNS resolver has been made more defensive against incorrect results.
Own Id: OTP-17578 Aux Id: ERIERL-683
When binary_to_term/2 failed, the extended error information would always blame the second argument even if the actual error was in the first argument.
Own Id: OTP-17591 Aux Id: GH-5171
On 32-bit computers, binary_to_term/1,2 is now more resilient against corrupted binaries containing maps in the external format.
Own Id: OTP-17604
A call to process_info(Pid, status) could erroneously report the status running when it should have reported waiting. This occurred when the calling process was executing on a higher priority than the process being inspected. This bug has been present since OTP 21.0 (erts version 10.0).
Own Id: OTP-17628

Improvements and New Features

Optimize memory usage of erts internal processes used during code loading/purging by hibernating them after a long time of inactivity.
Own Id: OTP-17426 Aux Id: PR-4785
Add the type erlang:stacktrace/0.
Own Id: OTP-17453 Aux Id: PR-4764
The arity argument of error/2,3 can now be none to indicate that the calling functions arity should be used.
Own Id: OTP-17456 Aux Id: PR-4764
Optimize match spec compiler for immediate (single word) constant terms.
Own Id: OTP-17469
Functions erlang:set_cookie(Cookie) and erlang:get_cookie(Node) have been added for completeness and to facilitate configuring distributed nodes with different cookies.
The documentation regarding distribution cookies has been improved to be less vague.
Own Id: OTP-17538 Aux Id: GH-5063, PR-5111
A workaround has been implemented for Linux's quirky behaviour to not adjust the source IP address when connecting a connected (reconnecing) UDP socket.
The workaround is to, on Linux, always dissolve any connection before connecting an UDP socket.
Own Id: OTP-17559 Aux Id: GH-5092, PR-5120
The internal documentation for how to use Yielding C Fun (YCF) has been updated to contain text about best practices for using YCF for ERTS.
Own Id: OTP-17596
Optimize garbage collection for processes with large number of binaries, funs and/or external pids/ports/refs.
Own Id: OTP-17602 Aux Id: PR-5149

Erts 12.0.4

Fixed Bugs and Malfunctions

A call to the process_info() BIF could end up hanging for ever due to a bug introduced when the new selective receive optimization was introduced in OTP 24.0. Note that this bug only effects process_info().
Own Id: OTP-17548 Aux Id: PR-5078, OTP-10391
Fix buffer overrun problem in the tty driver. The problem happens on some platforms when using the CTRL+R functionality of newshell with very long strings in the history.
Own Id: OTP-17560 Aux Id: GH-5116
Fix race-condition that could cause a crash when tracing scheduling or garbage collections on a process that was running on a dirty scheduler.
Own Id: OTP-17568 Aux Id: PR-4940
Fix rare bug where re:run would crash/return invalid results when given a subbinary as subject.
This bug has existed since Erlang/OTP 20.0.
Own Id: OTP-17585 Aux Id: GH-5150
binary_to_term/1,2 is now more resilient against corrupted binaries containing maps in the external format.
Own Id: OTP-17594

Erts 12.0.3

Fixed Bugs and Malfunctions

A call to erlang:cancel_timer(_, [{info, false}]) could cause the calling process to block forever in the call. Note that only the synchronous version of the call (that is, the async option is false) in combination with the info option set to false was effected by this bug.
Own Id: OTP-17472 Aux Id: PR-4932
Microstate accounting (msacc) and os:perf_counter() unintentionally used system time instead of monotonic time for time measurements on a lot of systems. These systems were all non x86/x86_64 systems or x86/x86_64 systems without a reliable and constant rdtsc instruction.
The lock counting (lcnt) built runtime system also unintentionally used system time instead of monotonic time for time measurements on all systems.
Own Id: OTP-17493
Simultaneous calls to erlang:system_flag(schedulers_online, _) could cause callers to end up in a suspended state forever.
Own Id: OTP-17500 Aux Id: GH-4809

Erts 12.0.2

Fixed Bugs and Malfunctions

Not yet handled alias-message signals in the signal queue at the time when a garbage collection was performed could cause a memory corruption which in turn could result in a crash of the runtime system. This bug was introduced in OTP 24.0.
Own Id: OTP-17431 Aux Id: GH-4858, PR-4870, OTP-16718
Fixed bug when using external pids/ports in keys of big maps (> 32). Could cause runtime crash. Bug exists since OTP 24.0.
Own Id: OTP-17436 Aux Id: PR-4875
After a node restart with init:restart/0,1, the module socket was not usable because supporting tables had been cleared and not re-initialized. This has now been fixed.
Handling of the "." domain as a search domain was incorrect and caused a crash in the DNS resolver inet_res, which has now been fixed.
Own Id: OTP-17439 Aux Id: GH-4827, PR-4888, GH-4838
A call to port_command() could cause a scheduler to end up in an eternal loop if the port was busy and the calling process had incoming signals at the time of the call. This bug was introduced in OTP 23.3.2 (ERTS version 11.2.1), OTP 22.3.4.18 (ERTS version 10.7.2.10), and OTP 21.3.8.23 (ERTS version 10.3.5.18).
Own Id: OTP-17448 Aux Id: GH-4898, PR-4903, OTP-17291
Bug fixes and code cleanup for the new socket implementation, such as:
Assertions on the result of demonitoring has been added in the NIF code, where appropriate.
Internal state handling for socket close in the NIF code has been reviewed.
Looping over close() for EINTR in the NIF code has been removed, since it is strongly discouraged on Linux and Posix is not clear about if it is allowed.
The inet_backend temporary socket option for legacy gen_tcp sockets has been documented.
The return value from net:getaddrinfo/2 has been corrected: the protocol field is now an atom/0, instead of, incorrectly, list(atom()). The documentation has also been corrected about this return type.
Deferred close of a socket:sendfile/* file was broken and has been corrected.
Some debug code, not enabled by default, in the socket NIF has been corrected to not accidentally core dump for debug printouts of more or less innocent events.
Own Id: OTP-17452
Dirty execution of a process in combination with an unlink signal from a port to the process could cause the signal queue of the process to enter into an inconsistent state. The result of the inconsistency typically caused a crash of the runtime system. This bug was introduced in OTP 23.3 (ERTS version 11.2).
Own Id: OTP-17462 Aux Id: GH-4885, PR-4914, OTP-17127

Erts 12.0.1

Fixed Bugs and Malfunctions

Commit of generated configure script.
Own Id: OTP-17420 Aux Id: OTP-17398, GH-4821

Erts 12.0

Fixed Bugs and Malfunctions

file:open/2 now throws an badarg error when opened with both the ram and raw options.
Own Id: OTP-16822 Aux Id: PR-2723
The estone benchmark has been updated to better reflect changes in the compiler and run-time system.
Own Id: OTP-16879
Fix profile guided optimization of run-time system when using GCC 7 or later.
Own Id: OTP-16880
Fix double close of fd when creating crash dump.
Own Id: OTP-16884
Improve erl error message when unable to open included args_file.
Own Id: OTP-17014
Remove warning text about the -- operation from documentation
The -- operation was optimized in Erlang/OTP 22 so that its worst case complexity is O(Nlog(N)), where N is the total size of the input lists. Therefore, the warning in the documentation saying that the time complexity is proportional to length(A)length(B) is incorrect and is no longer needed. Notice that Erlang/OTP 21 will no longer be supported when Erlang/OTP 24 gets released.
Own Id: OTP-17020
A floating point zero (0.0) can be both positive (+0.0) and negative (-0.0). Multiple bugs in the compiler, runtime system, and STDLIB have been fixed to ensure that the minus sign on 0.0 is not lost.
Own Id: OTP-17077 Aux Id: ERL-1431, PR-2903, PR-2905, PR-2906
Fix compiler warnings produced by the clang compiler.
Own Id: OTP-17105 Aux Id: PR-2872
Windows process erl.exe killed if its service process erlsrv.exe terminates.
Own Id: OTP-17131 Aux Id: PR-3031, GH-4360
The configure scripts in crypto and erts now fail if a requested feature cannot be enabled.
Large parts of the configure script of crypto have been rewritten with various improvements and bug fixes. It is now better at finding usable OpenSSL libraries, but will in the following cases fail to detect OpenSSL libraries where it previously sometimes detected the libraries by chance:
- OpenSSL installations with include directory and lib directory parts installed in different base directories. In order to detect such installations after this change, the user must explicitly specify the locations using the --with-ssl=<path> and the --with-ssl-incl=<path> configure command line arguments.
- When building with old gcc compilers or other compilers on Debian derivatives with multiarch directories under the lib directory. In order to detect such installations after this change, the user must explicitly specify the multiarch directory name using the --with-ssl-lib-subdir=lib/<multiarch-dir> configure command line argument.
Own Id: OTP-17254 Aux Id: ERIERL-618, GH-4230
The erl command line arguments +Bi, +Bd, and +B erroneously caused reception of the USR1 signal to terminate the runtime system without creating a crash dump. Reception of the USR1 signal now always cause termination with creation of a crash dump, regardless of command line arguments passed. This bug has existed at least since OTP R5B.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-17275 Aux Id: PR-4553
Add check to make sure that when passing an option to erl that requires an argument, but none is given, we report an error. This fixes a bug introduced in OTP-22.1 via OTP-15926.
Own Id: OTP-17314 Aux Id: OTP-15926, GH-4624, PR-
The "Last calls" section in crash dumps have been updated to print newlines after each non-function save_calls state (send, receive, timeout).
Own Id: OTP-17329 Aux Id: PR-4730
Sockets created with socket:accept not counted (socket:info/0).
Own Id: OTP-17372

Improvements and New Features

The experimental socket module can now use any protocol (by name) the OS supports. Suggested in PR-2641, implemented in PR-2670.
Own Id: OTP-14601 Aux Id: PR-2641, PR-2670, OTP-16749
New functions enif_dynamic_resource_call enables NIFs to call native code in another NIF module. The call is done via a resource callback function dyncall supplied by the user with the new enif_init_resource_type.
Own Id: OTP-14753
Runtime support for new improved selective receive optimization.
Own Id: OTP-16226 Aux Id: OTP-10391
The deprecated function erlang:get_stacktrace/0 has been removed. Use the new syntax in try/catch to retrieve the stack backtrace.
Own Id: OTP-16653
Support for handling abstract code created before OTP R15 has been dropped.
Own Id: OTP-16678 Aux Id: PR-2627
Extended error information for failing BIF calls as proposed in EEP 54 has been implemented.
When a BIF call from the Erlang shell fails, more information about which argument or arguments that were in error will be printed. The same extended error information will by proc_lib, common_test, and qlc when BIF calls fail.
For applications that wish to provide the same extended error information, there are new functions erl_error:format_exception/3 and erl_error:format_exception/4.
There is a new error/3 BIF that allows applications or libraries to provide extended error information in the same way for their own exceptions.
Own Id: OTP-16686
The erlang module documentation has been updated to improve clarity and description of edge cases.
Own Id: OTP-16687 Aux Id: PR-2996 PR-2762
An example implementation of Erlang distribution over UDS using distribution processes has been introduced.
Thanks to Jérôme de Bretagne
Own Id: OTP-16703 Aux Id: PR-2620
Improve code generation when creating funs by adding a new beam instruction make_fun3 that does not do GC and allows for better register allocation.
Own Id: OTP-16712
The process alias feature as outlined by EEP 53 has been introduced. It is introduced in order to provide a lightweight mechanism that can prevent late replies after timeout or connection loss. For more information, see EEP 53 and the documentation of the new alias/1 BIF and the new options to the monitor/3 BIF.
The call operation in the framework used by gen_server, gen_statem, and gen_event has been updated to utilize alias in order to prevent late responses. The gen_statem behavior still use a proxy process in the distributed case, since it has always prevented late replies and aliases won't work against pre OTP 24 nodes. The proxy process can be removed in OTP 26.
The alias feature also made it possible to introduce new functions similar to the erpc:receive_response() function in the gen behaviors, so the new functions gen_server:receive_response(), gen_statem:receive_response(), gen_event:receive_response() have also been introduced.
Own Id: OTP-16718 Aux Id: PR-2735
Accept 64-bit process identifiers from external nodes. This is the first step in an upgrade path toward using 64-bit pids in a future OTP release.
Own Id: OTP-16720 Aux Id: PR-2680
The experimental new socket API has been further developed. Some backwards incompatible changes with respect to OTP 23 have been made.
The control message format has been changed so a decoded value is now in the 'value' field instead of in the 'data' field. The 'data' field now always contains binary data.
Some type names have been changed regarding message headers and control message headers.
socket:bind/2 now returns plain ok instead of {ok, Port} which was only relevant for the inet and inet6 address families and often not interesting. To find out which port was chosen use socket:sockname/1.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-16749 Aux Id: OTP-14601
Remove old unused +MYm and ERL_MALLOC_LIB options.
Own Id: OTP-16788
Increase timer resolution on windows.
Own Id: OTP-16814 Aux Id: PR-2704
The code loader has been rewritten in order to be able to load JIT:ed code. As a consequence of this, it is no longer possible to load HiPE code.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-16878
Add support in the Erlang/OTP build system to generate a compilation database that can be used by third-party tools (such as irony in Emacs) to compile the erts C and C++ source code. Create the database using make compdb.
Own Id: OTP-16881
The BeamAsm JIT-compiler has been added to Erlang/OTP. The JIT-compiler is enabled by default on most x86 64-bit platforms that have a C++ compiler that can compile C++17. To verify that a JIT enabled emulator is running you can use erlang:system_info(emu_flavor).
For more information see the internal documentation of BeamAsm in erts.
Own Id: OTP-16885 Aux Id: PR-2745
By default all ERTS internal memory allocators based on alloc_util will now use their own separate carrier pool for migration of carriers instead of using a node global carrier pool. This was the default behavior between OTP 17 and OTP 21, but changed to use a node global carrier pool as of OTP 22.0. Usage of the node global carrier pool proved troublesome since it had a tendency to spread long lived blocks into allocators with normally short lived blocks causing increased memory fragmentation. The node global carrier pool behavior as well as other behaviors can be configured using the +M<S>cp command line argument.
Own Id: OTP-16898 Aux Id: OTP-16856
New functions have been added to the maps module: merge_with/3, intersect/2, intersect_with/3, filtermap/2, from_keys/2, and maps:foreach/2.
maps:merge_with/3 is the same as merge/2 but takes an extra fun that is used to combine items with the same key.
maps:intersect/2 computes the intersection of two maps.
maps:intersect_with/3 is the same as intersect/2 but takes an extra fun that is used to combine intersecting items.
maps:filtermap/2 allows filtering and mapping of a map in a single pass.
maps:from_keys/2 constructs a map from a list of keys and a single value and can be used to optimize sets operations such as from_list/1, filter/2, intersection/2, and subtract/2.
maps:foreach/2 allows iteration over a map without returning any value.
Own Id: OTP-16936 Aux Id: ERL-1367
Change escripts to output any errors or warnings to standard error instead of standard out.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-16945
A new erl parameter for specifying a file descriptor with configuration data has been added. This makes it possible to pass the parameter "-configfd FD" when executing the erl command. When this option is given, the system will try to read and parse configuration parameters from the file descriptor.
Own Id: OTP-16952
The experimental HiPE application has been removed, together with all related functionality in other applications.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-16963
The pretty printer for floating point number have been changed to make it easier to see if the integer part of the number has been rounded. After the change the digit that may have been rounded always appears last or just before the exponent character (e or E). This is accomplished by always printing the number using scientific notation if it is so large that the integer part could be rounded.
Own Id: OTP-16980 Aux Id: ERL-1308
The erlang:monitor_node/2 BIF will now fail with a notalive exception if distribution has not been started on the current node; it used to fail with a badarg exception.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-16987
Accept references up to a size of 160-bits from remote nodes. This is the first step in an upgrade path toward using references up to 160-bits in a future OTP release.
Own Id: OTP-17005 Aux Id: OTP-16718
Accept 64-bit port identifiers from external nodes. This is the first step in an upgrade path toward using 64-bit port identifiers in a future OTP release.
Own Id: OTP-17007
One can now pass the ERL_ROOTDIR environment variable to the erl and start scrips. This makes it easier to use Erlang for Android apps. On Android, apps don't control where they will be installed.
Own Id: OTP-17028
All long running functions in the maps API are now yielding. In previous releases the functions maps:from_list/1, maps:keys/1 and maps:values/1 did not yield. This could cause unfair scheduling of processes.
Own Id: OTP-17057
socket:sendfile/2,3,4,5 has been implemented, for platforms that support the underlying socket library call.
Own Id: OTP-17154 Aux Id: OTP-16749
The bit matching and construction syntax now supports 16-bit floats (IEEE 754-2008).
Own Id: OTP-17207
Add process_flag(fullsweep_after, N) to change fullsweep_after value in an already spawned process.
Own Id: OTP-17285 Aux Id: PR-4651
The max_heap_size error report has been updated to include the message queue size.
Own Id: OTP-17293 Aux Id: PR-4672
Introduce new types nonempty_binary/0 and nonempty_bitstring/0.
Own Id: OTP-17301 Aux Id: GH-4636
Optimize updates of large maps with identical keys and values. E.g. in the example below the original Map will be reused as the return of the second update.
1> Map = LargeMap#{ a => b }.
2> Map#{ a := b }.
The same optimization was done for small maps (< 33 keys) in erts-10.4 (OTP 22.0).
Own Id: OTP-17310 Aux Id: PR-4656
The previously undocumented internal -no_epmd option has been made documented and public.
Own Id: OTP-17341 Aux Id: PR-2945
Reduce memory carrier super alignment on 64-bit architectures. In practice allows more fine grained control over configuration of memory carrier sizes, from increments of 256kb to 16kb.
Own Id: OTP-17368

Erts 11.2.2.18

Fixed Bugs and Malfunctions

Fix list_to_atom/1 for negative code points. Could either return with a positive code point or fail with an incorrect exception.
Own Id: OTP-18321
A race condition which was very rarely triggered could cause the signal queue of a process to become inconsistent causing the runtime system to crash.
Own Id: OTP-18388 Aux Id: OTP-17462, PR-6662
process_info(Pid, status) when Pid /= self() could return an erroneous result.
Own Id: OTP-18421 Aux Id: PR-6806
In rare circumstances, when a process exceeded its allowed heap size set by option max_heap_size, it would not be killed as it should be, but instead enter a kind of zombie state it would never get out of.
Own Id: OTP-18463 Aux Id: PR-6858
Implementations of the call() driver callback that returned a faulty encoded result could cause a memory leak and could cause invalid data on the heap of the processes calling erlang:port_call/3.
Own Id: OTP-18525 Aux Id: PR-7049
If a runtime system which was starting the distribution already had existing pids, ports, or references referring to a node with the same nodename/creation pair that the runtime system was about to use, these already existing pids, ports, or references would not work as expected in various situations after the node had gone alive. This could only occur if the runtime system was communicated such pids, ports, or references prior to the distribution was started. That is, it was extremely unlikely to happen unless the distribution was started dynamically and was even then very unlikely to happen. The runtime system now checks for already existing pids, ports, and references with the same nodename/creation pair that it is about to use. If such are found another creation will be chosen in order to avoid these issues.
Own Id: OTP-18570 Aux Id: PR-7190

Erts 11.2.2.17

Fixed Bugs and Malfunctions

Notifications about available distribution data sent to distribution controller processes could be lost. Distribution controller processes can be used when implementing an alternative distribution carrier. The default distribution over tcp was not effected and the bug was also not present on x86/x86_64 platforms.
Own Id: OTP-18258 Aux Id: GH-6309, PR-6324

Erts 11.2.2.16

Fixed Bugs and Malfunctions

Distributed exit signals could be lost under the following conditions:
- An exit signal from a parent process to a child process was lost if:
  - the parent process terminated before the spawn request that created the child had completed,
  - the spawn request set up a link between parent and child
  - the spawn request was distributed, and
  - the exit reason was larger than one machine word.
- Loss of a connection over which a not yet completed spawn request was ongoing could cause loss of exit signals. Such loss of exit signals was very rare. Besides the above described connection loss also the following conditions had to be satisfied:
  - The spawn request that was interrupted by the connection loss also had to set up a link between the parent process and the child process.
  - The parent process that issued the spawn request also had to be terminating while the spawn request was interrupted by the connection loss.
  - The same parent process also had to have made other spawn requests to other nodes than to the node to which the connection was lost.
  - These spawn requests to the other nodes also had to set up links.
  - These spawn requests to the other nodes also had to be not yet completed at the time of the connection loss. That is, the spawn reply from the child process had not yet reached the parent process.
  If all the conditions above were met, exit signals to the children spawned due to the above described spawn requests to other nodes could be lost.
  The above bug also caused a significant memory leak when it was triggered since the destruction of the parent process never completed.
Own Id: OTP-18164 Aux Id: PR-6114
A race could cause process_info(Pid, message_queue_len) on other processes to return invalid results.
Own Id: OTP-18169 Aux Id: PR-6134
Fixed reduction counting for handling process system tasks.
Own Id: OTP-18170 Aux Id: PR-6135
Priority elevation of terminating processes did not work which could cause execution of such processes to be delayed.
Own Id: OTP-18175 Aux Id: PR-6142
An unlink operation made by a process that terminated before the unlink operation completed, i.e., before it had received an unlink-ack signal from the linked process, caused an exit signal to erroneously be sent from the terminating process to the process being unlinked. This exit signal would most often be ignored by the receiver, but if the receiver of the exit signal concurrently set up a new link, it could receive the exit signal with the actual exit reason of the terminating process instead of a noproc exit reason. It is however very hard to detect that this has happened and has no obvious negative consequences, so it should be considered harmless.
A distributed unlink-ack signal received by a terminating process was also not properly removed which could cause a minor memory leak.
Own Id: OTP-18177 Aux Id: PR-6150
The erlang:monotonic_time/1, erlang:system_time/1, erlang:time_offset/1, and os:system_time/1 BIFs erroneously failed when passed the argument native.
Own Id: OTP-18197 Aux Id: GH-6165, PR-6213
Fix writing and reading of more than 2 GB in a single read/write operation on macOS. Before this fix attempting to read/write more than 2GB would result in {error,einval}.
Own Id: OTP-18222 Aux Id: PR-6248 GH-6242

Erts 11.2.2.15

Fixed Bugs and Malfunctions

Fix faulty distribution encoding of terms with either
- a fun with bit-string or export-fun in its environment when encoded toward a not yet established (pending) connection
- or a fun with a binary/bitstring, in its environment, referring to an off-heap binary (larger than 64 bytes).
The symptom could be failed decoding on the receiving side leading to aborted connection. Fix OTP-18093 is a workaround for theses bugs that makes the VM accepts such faulty encoded funs.
The first encoding bug toward pending connection exists only in OTP 23 and 24, but the second one exists also on OTP 25.
Own Id: OTP-18104 Aux Id: OTP-18093

Erts 11.2.2.14

Fixed Bugs and Malfunctions

Accept funs (NEW_FUN_EXT) with incorrectly encoded size field. This is a workaround for a bug (OTP-18104) existing in OTP 23 and 24 that could cause incorrect size fields in certain cases. The emulator does not use the decoded size field, but erl_interface still does and is not helped by this workaround.
Own Id: OTP-18093 Aux Id: OTP-18104, PR-5987
The zlib built in to the runtime system has been updated to version 1.2.12. (Note that on most platforms, the platform's own zlib is used.)
Own Id: OTP-18123 Aux Id: GH-5994
Fixed emulator crash that could happen during crashdump generation of ETS tables with options ordered_set and {write_concurrency,true}.
Own Id: OTP-18144 Aux Id: GH-5981

Erts 11.2.2.13

Fixed Bugs and Malfunctions

Let EPMD tolerate failure when binding to IPv4/IPv6 loopback intefaces in addition to user-supplied addresses via ERL_EPMD_ADDRESS or the -address option. This can happen, for example, if the host system has ipv6 disabled via the disable_ipv6 sysctl.
Own Id: OTP-17970 Aux Id: PR-5762
Fixed a rare bug in binary_to_term/1, enif_make_map_from_arrays, erl_drv_send_term, and Erlang distribution that could crash the emulator.
Own Id: OTP-18027
Fixed a rare race in persistent_term:get/1,2 that could cause it to return the value of another key.
Own Id: OTP-18065 Aux Id: GH-5908
Fix bug where the process message queue was left in an inconsistent state when changing from on_heap to off_heap message queue data causing the GC to segfault.
Own Id: OTP-18075 Aux Id: PR-5927
Fix functions that convert universal to localtime (such as erlang:localtime/0 and erlang:universaltime_to_localtime/1) to fetch the correct localtime if it is changed after the start of the VM.
Own Id: OTP-18076 Aux Id: ERIERL-802 PR-5905
Fix memory leak when a process doing a distributed fragmented send is sent an exit signal. Before this fix the receiving node would be left with an incomplete message that would remain until the nodes were disconnected. The bug has existed since Erlang/OTP 21.
Own Id: OTP-18077 Aux Id: GH-5876 PR-5892

Erts 11.2.2.12

Fixed Bugs and Malfunctions

Fix Erlang monotonic time on MacOS. Previously used OS monotonic time primitive on MacOS is buggy and will not be used anymore. It has been replaced with usage of another OS monotonic time primitive that does not appear to be buggy.
Own Id: OTP-17998 Aux Id: PR-5825, GH-5554

Erts 11.2.2.11

Fixed Bugs and Malfunctions

By default global does not take any actions to restore a fully connected network when connections are lost due to network issues. This is problematic for all applications expecting a fully connected network to be provided, such as for example mnesia, but also for global itself. A network of overlapping partitions might cause the internal state of global to become inconsistent. Such an inconsistency can remain even after such partitions have been brought together to form a fully connected network again. The effect on other applications that expects that a fully connected network is maintained may vary, but they might misbehave in very subtle hard to detect ways during such a partitioning.
In order to prevent such issues, we have introduced a prevent overlapping partitions fix which can be enabled using the prevent_overlapping_partitions kernel(6) parameter. When this fix has been enabled, global will actively disconnect from nodes that reports that they have lost connections to other nodes. This will cause fully connected partitions to form instead of leaving the network in a state with overlapping partitions. Note that this fix has to be enabled on all nodes in the network in order to work properly. Since this quite substantially changes the behavior, this fix is currently disabled by default. Since you might get hard to detect issues without this fix you are, however, strongly advised to enable this fix in order to avoid issues such as the ones described above. As of OTP 25 this fix will become enabled by default.
Own Id: OTP-17843 Aux Id: ERIERL-732, PR-5611
Fix memory leak when tracing on running on a process that only handle system tasks or non-message signals (for example process_info requests).
Own Id: OTP-17904 Aux Id: ERIERL-757

Erts 11.2.2.10

Fixed Bugs and Malfunctions

Fix GC emulator crash when spawn_request was used when message tracing was enabled.
Own Id: OTP-17871 Aux Id: PR-5612

Erts 11.2.2.9

Fixed Bugs and Malfunctions

Fixed a memory leak in file:read_file_info/2 and file:read_file/1 on Windows.
Own Id: OTP-17827 Aux Id: GH-5527

Improvements and New Features

Responsiveness of processes executing on normal or low priority could suffer due to code purging or literal area removal on systems with a huge amount of processes. This since during these operations all processes on the system were scheduled for execution at once.
This problem has been fixed by introducing a limit on outstanding purge and copy literal requests in the system. By default this limit is set to twice the amount of schedulers on the system. This will ensure that schedulers will have enough work scheduled to perform these operations as quickly as possible at the same time as other work will be interleaved to a much higher degree. Performance of these operations will however be somewhat degraded due to the overhead of enforcing this limit compared to when using a very large limit.
This limit can be set by passing the +zosrl command line argument to erl, or by calling erlang:system_flag(outstanding_system_requests_limit, NewLimit).
Own Id: OTP-17796 Aux Id: ERIERL-729, PR-5473

Erts 11.2.2.8

Fixed Bugs and Malfunctions

The runtime system could call select() with a too large timeout value when executing on MacOS. This could in turn cause the runtime system to crash.
Own Id: OTP-17735 Aux Id: GH-5339
Certain distributed signals that for various reasons must to be forced into the distribution buffer even when it is full would instead be lost if the distribution buffer was full when sent. The effected signals:
- EXIT signals with exit reasons of one word size.
- DOWN signals with exit reasons of one word size.
- demonitor signals from a terminating process.
- unlink_ack signals on OTP 23 and 24.
- spawn_reply signals on OTP 23 and 24.
Own Id: OTP-17737 Aux Id: GH-5346, GH-4989

Erts 11.2.2.7

Fixed Bugs and Malfunctions

A call to process_info(Pid, status) could erroneously report the status running when it should have reported waiting. This occurred when the calling process was executing on a higher priority than the process being inspected. This bug has been present since OTP 21.0 (erts version 10.0).
Own Id: OTP-17628
A race between an exiting port and handling of simultaneously received signals to that port could cause a runtime system crash. The effected signals are link, monitor and demonitor. On OTP 22 a similar race could also cause a memory leak when receiving an unlink signal.
Own Id: OTP-17642 Aux Id: PR-5248
The message queue of a process entered an inconsistent state after a receive expression with an invalid timeout value was executed. If the exception raised due to the invalid timeout value was caught, the following receive expression executed by the process could fail to match messages already present in the message queue.
On OTP 24 this could also cause the whole runtime system to crash.
Own Id: OTP-17651 Aux Id: GH-5235, PR-5244
Sending a Port ! {PortOwner, close} signal from a process other than the port owner could erroneously trigger a badsig exit signal being sent to the port owner process even though the correct PortOwner had been passed in the signal.
Own Id: OTP-17665 Aux Id: PR-5248
This fixes a bug in erts_factory_undo that caused the heap to not be reset correctly. The erts_factory_undo function is, for example, called when a binary_to_term/1 call fails to reset the heap to its state before the binary_to_term/1 call. This can cause the heap to contain invalid terms which potentially can cause issues (e.g., crashes) when the whole heap is scanned.
Own Id: OTP-17677
Fix bug in persistent_term when a key-value pair contains a magic reference that is referred more than once. Magic references are NIF resources or returned from BIFs like ets:new, atomics:new. The bug could cause the memory of the referred resource to be prematurely deallocated.
The bug also apply to magic references in message passing on a runtime built with configure option --enable-sharing-preserving.
Bug exist for 64-bit since OTP-24.0 and for 32-bit since OTP-20.0.
Own Id: OTP-17700 Aux Id: GH-5271, PR-5273

Improvements and New Features

The python scripts that existed in erts/lib_src/yielding_c_fun/lib/tiny_regex_c/scripts had a license that was incompatible with Erlang/OTP's license. This ticket removes these scripts that were not used by us.
Own Id: OTP-17658

Erts 11.2.2.6

Fixed Bugs and Malfunctions

Parsing of the result value in the native DNS resolver has been made more defensive against incorrect results.
Own Id: OTP-17578 Aux Id: ERIERL-683
On 32-bit computers, binary_to_term/1,2 is now more resilient against corrupted binaries containing maps in the external format.
Own Id: OTP-17604

Erts 11.2.2.5

Fixed Bugs and Malfunctions

Fix buffer overrun problem in the tty driver. The problem happens on some platforms when using the CTRL+R functionality of newshell with very long strings in the history.
Own Id: OTP-17560 Aux Id: GH-5116
Fix race-condition that could cause a crash when tracing scheduling or garbage collections on a process that was running on a dirty scheduler.
Own Id: OTP-17568 Aux Id: PR-4940
Fix rare bug where re:run would crash/return invalid results when given a subbinary as subject.
This bug has existed since Erlang/OTP 20.0.
Own Id: OTP-17585 Aux Id: GH-5150
binary_to_term/1,2 is now more resilient against corrupted binaries containing maps in the external format.
Own Id: OTP-17594

Erts 11.2.2.4

Fixed Bugs and Malfunctions

Microstate accounting (msacc) and os:perf_counter() unintentionally used system time instead of monotonic time for time measurements on a lot of systems. These systems were all non x86/x86_64 systems or x86/x86_64 systems without a reliable and constant rdtsc instruction.
The lock counting (lcnt) built runtime system also unintentionally used system time instead of monotonic time for time measurements on all systems.
Own Id: OTP-17493
Simultaneous calls to erlang:system_flag(schedulers_online, _) could cause callers to end up in a suspended state forever.
Own Id: OTP-17500 Aux Id: GH-4809
Fix rare race bug in memory management of distribution entries. Have been seen to cause VM crash when massive number of repeated concurrent failing connection attempts.
Own Id: OTP-17513 Aux Id: GH-4964, PR-5015

Erts 11.2.2.3

Fixed Bugs and Malfunctions

A call to erlang:cancel_timer(_, [{info, false}]) could cause the calling process to block forever in the call. Note that only the synchronous version of the call (that is, the async option is false) in combination with the info option set to false was effected by this bug.
Own Id: OTP-17472 Aux Id: PR-4932

Erts 11.2.2.2

Fixed Bugs and Malfunctions

A call to port_command() could cause a scheduler to end up in an eternal loop if the port was busy and the calling process had incoming signals at the time of the call. This bug was introduced in OTP 23.3.2 (ERTS version 11.2.1), OTP 22.3.4.18 (ERTS version 10.7.2.10), and OTP 21.3.8.23 (ERTS version 10.3.5.18).
Own Id: OTP-17448 Aux Id: GH-4898, PR-4903, OTP-17291
Dirty execution of a process in combination with an unlink signal from a port to the process could cause the signal queue of the process to enter into an inconsistent state. The result of the inconsistency typically caused a crash of the runtime system. This bug was introduced in OTP 23.3 (ERTS version 11.2).
Own Id: OTP-17462 Aux Id: GH-4885, PR-4914, OTP-17127

Erts 11.2.2.1

Fixed Bugs and Malfunctions

Commit of generated configure script.
Own Id: OTP-17420 Aux Id: OTP-17398, GH-4821

Erts 11.2.2

Fixed Bugs and Malfunctions

Fix bug in match spec compilator seen to cause a stack overflow crash on debug VM for certain match specs. Could potentially cause problems for standard VM, but has not been verified. Match specs are used by ets:match/select functions and erlang:trace_pattern.
Own Id: OTP-17379 Aux Id: PR-4804

Erts 11.2.1

Fixed Bugs and Malfunctions

The following signals could pass before other signals from the same sender to the same receiver. That is, these signals could arrive too early.
- garbage-collect request. Sent from one process to another using one of the garbage_collect/0 BIFs.
- check-process-code request. Sent from one process to another using one of the check_process_code() BIFs.
- is-process-alive reply. Sent as a response to a process calling the is_process_alive() BIF.
- process-info reply. Sent as a response to a process calling one of the process_info() BIFs.
- port-command reply. Sent as a response to a process calling one of the port_command() BIFs.
- port-connect reply. Sent as a response to a process calling the port_connect() BIF.
- port-close reply. Sent as a response to a process calling the port_close() BIF.
- port-control reply. Sent as a response to a process calling the port_control() BIF.
- port-call reply. Sent as a response to a process calling the port_call() BIF.
- port-info reply. Sent as a response to a process calling one of the port_info() BIFs.
Own Id: OTP-17291
Fix bug in persistent_term:get/0 and info/0 that could cause VM crash in rare cases. Bug exists since OTP 23.0.
Own Id: OTP-17298
Fixed a bug in zlib where decompression would crash with data_error on some valid inputs.
Own Id: OTP-17299 Aux Id: GH-4710
A garbage collection of a literal area missed messages that entirely consisted of a term in a literal area. This could in turn lead to a crash of the runtime system.
Own Id: OTP-17307
A call to process_flag(message_queue_data, off_heap) could cause a crash of the runtime system when sequential tracing was enabled.
Own Id: OTP-17349

Erts 11.2

Fixed Bugs and Malfunctions

Fix memory leak of about 6 words when erlang:process_flag/3 is called with a pid of an already dead process. Bug exists since OTP-21.0.
Own Id: OTP-17081 Aux Id: PR-2930
Fixed small memory leak in erl_drv_send_term and erl_drv_output_term when failing due to the term being invalid.
Own Id: OTP-17089 Aux Id: PR-2934
The DTrace/SystemTap process_heap_grow probe is now called with valid the heap and stack pointers for the process in question.
Own Id: OTP-17096 Aux Id: PR-2932
Fixed a performance issue in memory allocation for Linux kernels that didn't support MADV_FREE.
Own Id: OTP-17124
A new link protocol has been introduced which prevents links from ending up in an inconsistent state where one participant considers itself linked while the other doesn't. This bug has always existed in the distributed case, but has since OTP 21 also existed in the node local case since the distributed link protocol then was adopted also for node local links. The bug could, however, only trigger if both participants operated on the link simultaneously.
Own Id: OTP-17127
Fix memory leak when receiving sigchld from port program to already dead port.
Own Id: OTP-17163
Fix bug where complex seq_trace tokens (that is lists, tuples, maps etc) could becomes corrupted by the GC. The bug was introduced in OTP-21.
Own Id: OTP-17209 Aux Id: PR-3039
Fixed WSLPATH environment variable addition to PATH on windows, the last character was lost.
Own Id: OTP-17229
Fixed a bug in the timer implementation which could cause timers that were set to more than 37.25 hours in the future to be delayed. This could occur if there were multiple timers scheduled to be triggered very close in time, but still at different times, and the scheduler thread handling the timers was not able to handle them quickly enough. Delayed timers were in this case triggered when another unrelated timer was triggered.
Own Id: OTP-17253
Fixed small memory leak in erlang:trace/3 if option {tracer,_} is included and the option list is invalid or the call races with a concurrent trace or code change operation.
Own Id: OTP-17265 Aux Id: PR-4596
Fix configure check for inet_pton on 32-bit windows. The failure of this check would cause epmd to be built without ipv6 support.
Own Id: OTP-17283

Improvements and New Features

Various address sanitizer support.
Own Id: OTP-16959 Aux Id: PR-2965
The emulator will now honor cgroup2 CPU quotas.
Own Id: OTP-17002
Improved memory barrier usage on ARMv8 hardware, and specifically on Apple silicon.
Own Id: OTP-17195 Aux Id: PR-4505, PR-4538
Improved memory barrier usage on 64-bit POWER hardware.
Own Id: OTP-17200 Aux Id: PR-4510
Fix a file descriptor leak when using sendfile and the remote side closes the connection. This bug has been present since OTP-21.0.
Own Id: OTP-17244
Refinement of the documentation of the message_queue_data process flag.
Own Id: OTP-17252 Aux Id: PR-4568

Erts 11.1.8

Fixed Bugs and Malfunctions

Fixed a bug that could cause some work scheduled for execution on scheduler threads to be delayed until other similar work appeared. Beside delaying various cleanup of internal data structures also the following could be delayed:
- Termination of a distribution controller process
- Disabling of the distribution on a node
- Gathering of memory allocator information using the instrument module
- Enabling, disabling, and gathering of msacc information
- Delivery of 'CHANGE' messages when time offset is monitored
- A call to erlang:cancel_timer()
- A call to erlang:read_timer()
- A call to erlang:statistics(io | garbage_collection | scheduler_wall_time)
- A call to ets:all()
- A call to erlang:memory()
- A call to erlang:system_info({allocator | allocator_sizes, _})
- A call to erlang:trace_delivered()
The bug existed on runtime systems running on all types of hardware except for x86/x86_64.
Own Id: OTP-17185

Erts 11.1.7

Improvements and New Features

Make windows installer remove write access rights for non admin users when installing to a non default directory. Reduces the risk for DLL sideloading, but the user should always be aware of the access rights for the installation.
Own Id: OTP-17097

Erts 11.1.6

Fixed Bugs and Malfunctions

The suspend_process() and resume_process() BIFs did not check their arguments properly which could cause an emulator crash.
Own Id: OTP-17080
The runtime system would get into an infinite loop if the runtime system was started with more than 1023 file descriptors already open.
Own Id: OTP-17088 Aux Id: ERIERL-580

Erts 11.1.5

Fixed Bugs and Malfunctions

Fix emulator crash when sending small bit-strings over Erlang distribution while the connection is being setup.
The fault was introduced in OTP-23.0
Own Id: OTP-17083 Aux Id: ERIERL-572

Erts 11.1.4

Fixed Bugs and Malfunctions

Fixed bug which could cause VM crash when a NIF is loaded at the same time as the Erlang implementation of the NIF is called. Bug exists since OTP 23.0.
Own Id: OTP-16859
Fixed enif_make_map_* functions in debug build when given environment from enif_alloc_env.
Own Id: OTP-16863 Aux Id: ERL-1352
Fixed broken configuration option --disable-pie.
Own Id: OTP-16864
Fixed rare distribution bug in race between received signal (link/monitor/spawn_request/spawn_reply) and disconnection. Symptom: VM crash. Since: OTP 21.0.
Own Id: OTP-16869 Aux Id: ERL-1337
Fixed a performance issue when extremely many items were stored in the process dictionary. (Fixing this bug also eliminates a compiler warning emitted by the latest version of Clang.)
Own Id: OTP-16888
Remove -ftree-copyrename from flags passed to compiler when building erts. The flag is not used by modern gcc's and is not supported by clang.
Own Id: OTP-16894
Modules using complicated nested binary comprehensions could fail to load.
Own Id: OTP-16899
Fixed a race in file:read_file/1 were an incomplete file could be returned if another OS process swapped the file out while reading.
Own Id: OTP-16948 Aux Id: PR-2792
The call list_to_integer("10", true) would return 4 instead of raising an exception. Certain other atoms would also be interpreted as a number base.
Own Id: OTP-17030
On macOS 11 (Big Sur), erl would not start if the maximum number of file descriptors were unlimited (ulimit -n unlimited).
Own Id: OTP-17055 Aux Id: ERL-1417

Improvements and New Features

Add manifest to all executables and dynamic libraries.
Own Id: OTP-17067 Aux Id: PR-2907

Erts 11.1.3

Fixed Bugs and Malfunctions

Fixed a crash when exceptions were thrown during call time tracing.
Own Id: OTP-16994

Erts 11.1.2

Fixed Bugs and Malfunctions

Fixed bugs causing issues when enabling the ERTS internal allocators on a system built with the undocumented and unsupported SMALL_MEMORY feature.
Own Id: OTP-16939
The inet driver used to use 16 as maximum elements in an I/O vector passed to writev() (and WSASend() on Windows). When the data to send contained lots of elements, this caused a performance degradation since repeated calls to writev() had to be made to a much larger extent. The inet driver now looks up actual maximum amount of elements that can be used on the system, instead of just assuming 16. On most systems this will result in a maximum amount of I/O vector elements of 1024.
As of OTP 23.0 the term encoding of signals to send over the distribution are encoded into I/O vectors of buffers instead of into a single buffer. Reference counted binaries are referred to directly from the I/O vector instead of being copied into the single buffer. That is, Erlang signals containing huge amounts of reference counted binaries was effected by this performance degradation.
Own Id: OTP-16955 Aux Id: ERL-1343, OTP-15618
In the distributed case, a faulty reply option in a call to the spawn_request() BIF erroneously caused a badarg exception instead of a badopt error message reply.
Own Id: OTP-16991 Aux Id: OTP-15251

Erts 11.1.1

Fixed Bugs and Malfunctions

inet:setopts([{active,once}]) wakes up IO polling thread unnecessarily, leading to lock contention and visibly higher CPU utilization.
Own Id: OTP-16847 Aux Id: ERL-1301
Two bugs in the ERTS internal thread wakeup functionality have been fixed. These bugs mainly hit when all threads in the system tried to go to sleep. When the bugs were triggered, certain operations were delayed until a thread woke up due to some other reason. Most important operations effected were code loading, persistent term updates, and memory deallocation.
Own Id: OTP-16870
Fixed bug in ets:select_replace/2 on compressed tables that could produce faulty results or VM crash. Bug exists since OTP 20.
Own Id: OTP-16874 Aux Id: ERL-1356, PR-2763
When compiling Erlang/OTP on macOS using Xcode 12, the performance of the BEAM interpreter would be degraded.
Own Id: OTP-16892

Improvements and New Features

As of OTP 22, the allocator specific memory carrier pools were replaced by a node global carrier pool. This unfortunately caused substantial memory fragmentation in some cases due to long lived data being spread into carriers used by allocators mainly handling short lived data.
A new command line argument +M<S>cp has been introduced with which one can enable the old behavior as well as configuring other behaviors for the carrier pools. In order to configure the old behavior, with allocator specific carrier pools for all allocators, pass +Mucp : (including the colon character) as a command line argument to erl when starting the Erlang system.
The default configuration for carrier pools will be changed to +Mucp : some time in the future, but not in this patch.
Own Id: OTP-16856

Erts 11.1

Fixed Bugs and Malfunctions

Update the documentation of the abstract format to use ANNO instead of LINE.
Own Id: OTP-16625 Aux Id: PR-2609
The emulator will no longer revert to the default number of schedulers when running under a CPU quota lower than 1 CPU.
Own Id: OTP-16710 Aux Id: ERL-1280
Fixed a problem with crash dumps. When a process that contained reference to literals internally created by the runtime system (such as the tuple returned by os:type/0), the literal would not be included in the crash dump and the crashdump viewer would complain about the heap being incomplete.
Own Id: OTP-16713
Fix configure detection of PGO for clang.
Own Id: OTP-16738
The to_erl program has been fixed to correctly interpret newline as only newline and not newline+return.
This bug would cause the terminal to behave strangely when using lines longer than the terminal size.
Own Id: OTP-16741
A race condition when changing process priority by calling process_flag(priority, Prio) could cause elevation of priority for a system task to be ignored. This bug hit if the system task was scheduled on the process calling process_flag() at the same time as the priority was changed. The bug is quite harmless and should hit very seldom if ever.
Own Id: OTP-16770
Adjust /bin/sh to /system/bin/sh in scripts when installing on Android.
Own Id: OTP-16833 Aux Id: PR-2729
In rare circumstances, when loading a BEAM file generated by an alternative code generator (not the Erlang compiler in OTP) or from handwritten or patched BEAM code, the loader could do an unsafe optimization.
Own Id: OTP-16850 Aux Id: ERL-1344
A memory and file descriptor leak in socket has been fixed. (When a newly opened socket that had not entered the fd into the VM's poll set (neither received, sent, accepted nor connected) was abandoned without closing (process died), after assigning a different controlling process, then a memory block and the file descriptor could be leaked.)
Own Id: OTP-16857
The documentation of statistics(run_queue) erroneously stated that it returns the total length of all normal run queues when it is the total length of all normal and dirty CPU run queues that is returned. The documentation has been updated to reflect the actual behavior.
Own Id: OTP-16866 Aux Id: ERL-1355

Improvements and New Features

Changes in order to build on the Haiku operating system.
Thanks to Calvin Buckley
Own Id: OTP-16707 Aux Id: PR-2638
When building the inet driver on Windows, there where many compiler warnings regarding type casting (used when calling the debug macro). This has now been resolved.
Own Id: OTP-16715
Make (use of) the socket registry optional (still enabled by default). Its now possible to build OTP with the socket registry turned off, turn it off by setting an environment variable and controlling in runtime (via function calls and arguments when creating sockets).
Own Id: OTP-16763
Change default filename encoding on android to UTF-8.
Own Id: OTP-16821 Aux Id: PR-2733
Clarification of the format of the atom cache header used by the distribution.
Own Id: OTP-16848 Aux Id: PR-2737

Erts 11.0.4

Fixed Bugs and Malfunctions

The ERTS internal I/O poll implementation could get into an inconsistent state causing input events to be ignored.
Own Id: OTP-16780 Aux Id: PR-2701

Erts 11.0.3

Fixed Bugs and Malfunctions

Fixed bug in erlang:load_nif/2 that could cause it to throw badarg exception if a concurrent code change operation was in progress. Bug existed since OTP 23.0.
Own Id: OTP-16704 Aux Id: ERL-1273, PR-16704
Minor fix of debug compiled VM.
Own Id: OTP-16717
An unintentional reuse of an already used emulator internal event object could cause a wakeup signal to a thread to be lost. In worst case this could cause the runtime system to hang. This hang was however quite rare.
Own Id: OTP-16766 Aux Id: ERL-1304
NIF threads and driver threads on non-Linux systems leaked internal resources when terminating. On Windows these resources were one event per thread. On most other systems one mutex and one condition variable per thread. On these other systems that also lacked pthread_cond_timedwait() also a pipe with its file descriptors was leaked.
Own Id: OTP-16772 Aux Id: ERL-1304

Erts 11.0.2

Fixed Bugs and Malfunctions

Fixed bug when sending an export fun (eg lists:reverse/1) on a not yet established connection. It could cause VM crash. Bug exists since OTP 23.0.
Own Id: OTP-16693 Aux Id: ERL-1254, PR-2640

Erts 11.0.1

Fixed Bugs and Malfunctions

The functionality utilized by BIFs for temporary disabling of garbage collection while yielding could cause system task queues to become inconsistent on a process executing such a BIF. Process system tasks are for example utilized when purging code, garbage collecting literal data, and when issuing an ordinary garbage collection from another process.
The bug does not trigger frequently. Multiple code purges in direct sequence makes it more likely that this bug is triggered. In the cases observed, this has resulted in a hanging code purge operation.
Own Id: OTP-16639 Aux Id: ERL-1236
SCTP and UDP recv/2,3 hangs indefinitely if socket is closed while recv is called (socket in passive mode).
Own Id: OTP-16654 Aux Id: ERL-1242

Erts 11.0

Fixed Bugs and Malfunctions

BIFs now behave like ordinary functions with regard to tracing, allowing call_count tracing and fixing a few bugs where return trace messages were lost when BIFs tail-called themselves or other functions ("trapping").
Own Id: OTP-14734 Aux Id: ERL-496
Fix various compiler warnings on 64-bit Windows.
Own Id: OTP-15800
erlang:fun_info(fun foo/1, name/1) used to return a function name based on the name of the function that fun foo/1 was used in. The name returned is now -fun.foo/1-.
Own Id: OTP-15837
file:allocate/3 will now update the file size on all platforms.
Own Id: OTP-16155 Aux Id: PR-2408
erlang:decode_packet with type set to httph no longer accepts http headers that have whitespaces in between the header name and the colon. That is:
Content-Type : text/html
is no longer allowed. This has been changed to conform with RFC 7230 and thus protect against http desync attacks.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-16168 Aux Id: ERL-1053
Fix the quoting rules in erl -args_file, ERL_FLAGS, ERL_AFLAGS and ERL_ZFLAGS to work as unix sh quoting.
This bug fix can make previous configuration options to erl passed through ERL_FLAGS, ERL_AFLAGS, ERL_ZFLAGS or -args_file not be interpreted in the same way as before the fix.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-16244 Aux Id: ERL-1051
Fix the Erlang distribution to handle the scenario when a node connects that can handle message fragmentation but can not handle the atom cache. This bug only affects users that have implemented a custom distribution carrier. It has been present since OTP-21.
The DFLAG_FRAGMENT distribution flag was added to the set of flags that can be rejected by a distribution implementation.
Own Id: OTP-16284
Compiling a match specification with excessive nesting caused the runtime system to crash due to scheduler stack exhaustion. Instead of crashing the runtime system, effected functions will now raise a system_limit error exception in this situation.
Own Id: OTP-16431 Aux Id: ERL-592
Fixed a bug that prevented Erlang from being started on Windows if it were installed on certain paths.
Own Id: OTP-16478 Aux Id: ERL-1115
Fix bug on Windows causing bad performance when standard input is closed, especially if the VM is only assigned one CPU core. Could be provoked for example by starting erl or escript via function os:cmd/1. Could be avoided with command line option -noinput.
The bad performance was caused by an io thread spinning indefinitely.
Own Id: OTP-16521 Aux Id: ERL-716
Fixed a bug on Unix platforms that would cause file:read_file_info/1 to return incorrect results if the emulator's effective user or group id differed from its actual ones.
Own Id: OTP-16571
socket: Compile problems on Android when PACKET_FASTROUTE and PACKET_USER are both defined and has the same value. Use of PACKET_FASTROUTE has been removed as it may be unused and also only for none user-land.
Own Id: OTP-16576 Aux Id: ERL-1208
Fixed bug in erl_crash.dump generation that could cause a SEGV core dump if a recently cancelled timer was found.
Own Id: OTP-16596 Aux Id: ERL-1105, PR-2606

Improvements and New Features

Improved concurrency of erlang:load_nif/2 as it does no longer block other schedulers from executing during initial load of a NIF library.
Own Id: OTP-10278
EEP-52 has been implemented.
In binary matching, the size of the segment to be matched is now allowed to be a guard expression, and similarly in map matching the keys can now be guard expressions. See the Erlang Reference Manual and Programming Examples for more details.
Language compilers or code generators that generate Core Erlang code may need to be updated to be compatible with the compiler in OTP 23. For more details, see the section Backwards Compatibility in EEP 52.
Own Id: OTP-14708
Internally in BEAM, handling of continuation pointers has been simplified. This change is not user-visible, except when examining a process stack in the crashdump viewer. The continuation pointer for a function will now be stored below the y(0) for that function.
Own Id: OTP-15077
seq_trace tokens are now propagated to spawned processes.
Own Id: OTP-15232 Aux Id: ERL-700
Improvements of distributed spawn operations. These include both scalability and performance improvements as well as new functionality.
New functionality:
- A distributed spawn_monitor() BIF.
- Support for monitor option in the distributed spawn_opt() BIF.
- New spawn_request() BIFs for asynchronous spawn of processes. spawn_request() supports all options that spawn_opt() support plus a few more.
Own Id: OTP-15251
Make ets:insert/2 and ets:insert_new/2 yield scheduler execution on long lists of records to insert.
Own Id: OTP-15517 Aux Id: ERL-560
Increased size of node incarnation numbers (aka "creation"), from 2 bits to 32 bits. This will reduce the risk of pids/ports/refs, from different node incarnation with the same name, being mixed up.
Own Id: OTP-15603
The runtime system can now encode Erlang terms to the Erlang external term format as I/O vectors. The main benefit of this is that reference counted binaries can be referred to directly instead of copied into a new binary.
The default Erlang distribution over TCP will always utilize this. Alternate distribution implementations utilizing a port as distribution controller will utilize this if the driver implements the outputv callback. Alternate Erlang distribution implementations utilizing a process as distribution controller will utilize this if I/O vectors are utilized by the functionality that processes the data returned from erlang:dist_ctrl_get_data().
The return type for data returned by erlang:dist_ctrl_get_data() has been changed from iodata/0 to iovec(). Note that iovec() data is valid iodata/0 so old implementations using erlang:dist_ctrl_get_data() do not need to be changed, but may benefit from being changed depending on usage scenario.
The new BIFs term_to_iovec/1 and term_to_iovec/2 have been introduced. These work exactly as term_to_binary() with the corresponding arity except the return type.
Own Id: OTP-15618
Improved ETS scalability of concurrent calls that change the size of a table, like ets:insert/2 and ets:delete/2.
This performance feature was implemented for ordered_set in OTP 22.0 and does now apply for all ETS table types.
The improved scalability may come at the cost of longer latency of ets:info(T,size) and ets:info(T,memory). A new table option decentralized_counters has therefore been added. It is default true for ordered_set with write_concurrency enabled and default false for all other table types.
Own Id: OTP-15744 Aux Id: OTP-15623, PR-2229
Directories can now be opened by file:open/2 when passing the directory option.
Own Id: OTP-15835 Aux Id: PR-2212
Add Hygon Dhyana as known processor to enable support for atomic operations.
Own Id: OTP-15840
Make erlang:phash2 functions consume reductions proportional to the size of the input term and yield scheduler when reductions are depleted.
Own Id: OTP-15842 Aux Id: PR-2182
Fix various build issues when compiling Erlang/OTP to the IBM AIX platform.
Own Id: OTP-15866 Aux Id: PR-2110
Add configure options --enable-pie and --disable-pie to control the build of position independent executables.
Own Id: OTP-15868
file:read_file_info/2 can now be used on opened files and directories.
Own Id: OTP-15956 Aux Id: PR-2231
Add arity-1 versions of atom_to_binary, binary_to_atom and binary_to_existing_atom, all with utf8 as default encoding.
Own Id: OTP-15995 Aux Id: PR-2358
Optimized the erts internal hash table implementation for faster lookups. The internal hash is used for things like; the process registry, executing erlang:apply/2, executing M:func(test), and more.
Own Id: OTP-16014 Aux Id: PR-2345
CPU quotas are now taken into account when deciding the default number of online schedulers, improving performance in container environments where quotas are applied, such as docker with the --cpus flag.
Own Id: OTP-16105 Aux Id: ERL-927
The -config option to erl now can take multiple config files without repeating the -config option. Example:
erl -config sys local
Own Id: OTP-16148 Aux Id: PR-2373
Removed the scheduler_poll and async I/O dtrace and LTTng trace probes.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-16215
Optimized persistent_term:put/2 and erase/1 to consume less CPU in many cases.
Own Id: OTP-16237 Aux Id: PR-2389
The possibility to run Erlang distribution without relying on EPMD has been extended. To achieve this a couple of new options to the inet distribution has been added.
- -dist_listen false - Setup the distribution channel, but do not listen for incoming connection. This is useful when you want to use the current node to interact with another node on the same machine without it joining the entire cluster.
- -erl_epmd_port Port - Configure a default port that the built-in EPMD client should return. This allows the local node to know the port to connect to for any other node in the cluster.
The erl_epmd callback API has also been extended to allow returning -1 as the creation which means that a random creation will be created by the node.
In addition a new callback function called listen_port_please has been added that allows the callback to return which listen port the distribution should use. This can be used instead of inet_dist_listen_min/max if the listen port is to be fetched from an external service.
Own Id: OTP-16250
On systems without closefrom(), such as Linux, iterating over all possible file descriptors and calling close() for each is inefficient. This is markedly so when the maximum number of file descriptors has been tuned to a large number.
Instead, in erl_child_setup, walk the open descriptors under /dev/fd and close only those which are open.
This optimization affects the CPU usage of starting a new Erlang instance.
Own Id: OTP-16270
Optimized maps:merge/2 for trivial cases of an empty map(s) or same map.
Own Id: OTP-16283 Aux Id: PR-2441
The new experimental socket module has been moved to the Kernel application.
Own Id: OTP-16312
Improved the presentation of allocations and carriers in the instrument module.
Own Id: OTP-16327
As announced in OTP 22.0, the previously existing limited support for VxWorks has now been removed.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-16329 Aux Id: OTP-15621
The return value when using the httph and httph_bin option to erlang:decode_packet/3 and inet:setopts/2 has been changed to also include the original header unmodified. See erlang:decode_packet/3. Example:
```
 >
      erlang:decode_packet(httph_bin,<<"HELLO:
      hi\r\n\r\n">>,[]).
      {ok,{http_header,0,<<"Hello">>,<<"HELLO">>,<<"hi">>},<<"\r\n">>}
```
Own Id: OTP-16347 Aux Id: PR-2466
Ensure net_kernel:monitor_nodes/1 sends nodedown messages of a failed connection before nodeup messages of a reestablished connection toward the same node.
Own Id: OTP-16362
Update of sequential tracing to also support other information transfers than message passing.
Own Id: OTP-16370 Aux Id: OTP-15251, OTP-15232
socket: It is now possible to create a socket from an already existing file descriptor.
Own Id: OTP-16398 Aux Id: ERL-1154
socket: The socket:supports/1 function now also report if netns is supported or not.
Own Id: OTP-16432
=:= has been optimized to return false immediately when comparing two maps of different sizes.
Own Id: OTP-16454
Changed the behaviour of passing the erl command line argument +A 0 to silently imply +A 1. That is, it will no longer be possible to completely disable the async thread pool. Disabling of the async thread pool has since OTP 21 had no benefits; only lots of drawbacks.
Own Id: OTP-16482
The deprecated erlang:get_stacktrace/0 BIF now returns an empty list instead of a stacktrace. To retrieve the stacktrace, use the extended try/catch syntax that was introduced in OTP 21. erlang:get_stacktrace/0 is scheduled for removal in OTP 24.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-16484
init:restart/1 has been introduced. init:restart/1 can be utilized for changing the code loading mode during a restart.
Own Id: OTP-16492 Aux Id: PR-2461
Improve configure for the net nif, which should increase portability.
Own Id: OTP-16530 Aux Id: OTP-16464
socket: Socket counters and socket global counters are now represented as maps (instead of property lists).
Own Id: OTP-16535
Reduced the resource usage of erlc in parallel builds (e.g. make -j128).
Own Id: OTP-16543 Aux Id: ERL-1186
The experimental socket module has gotten restrictions removed so now the 'seqpacket' socket type should work for any communication domain (protocol family) where the OS supports it, typically the Unix Domain.
Own Id: OTP-16550 Aux Id: ERIERL-476
Updated the internal pcre library to 8.44.
Own Id: OTP-16557
There is now cost in terms of reductions when copying binary data using the binary syntax.
Own Id: OTP-16601 Aux Id: OTP-16577
The executable erl_call is now part of the erts distribution in addition to erl_interface.
Own Id: OTP-16602
Fix a buffer overflow bug that caused EPMD to consume 100% CPU after many nodes had been connected on the same time on NetBSD.
Own Id: OTP-16615
erl -remsh now uses the dynamic node names feature by default. See the erl documentation for details.
Own Id: OTP-16616
socket: By default the socket options rcvtimeo and sndtimeo are now disabled. To enable these, OTP now has to be built with the configure option --enable-esock-rcvsndtimeo
Own Id: OTP-16620
The environment variable $HOME does no longer have to be set before Erlang can be started.
Own Id: OTP-16635 Aux Id: ERL-476 PR-2390

Erts 10.7.2.19

Fixed Bugs and Malfunctions

A race could cause process_info(Pid, message_queue_len) on other processes to return invalid results.
Own Id: OTP-18169 Aux Id: PR-6134
Fixed reduction counting for handling process system tasks.
Own Id: OTP-18170 Aux Id: PR-6135
Priority elevation of terminating processes did not work which could cause execution of such processes to be delayed.
Own Id: OTP-18175 Aux Id: PR-6142
The erlang:monotonic_time/1, erlang:system_time/1, erlang:time_offset/1, and os:system_time/1 BIFs erroneously failed when passed the argument native.
Own Id: OTP-18197 Aux Id: GH-6165, PR-6213
Notifications about available distribution data sent to distribution controller processes could be lost. Distribution controller processes can be used when implementing an alternative distribution carrier. The default distribution over tcp was not effected and the bug was also not present on x86/x86_64 platforms.
Own Id: OTP-18258 Aux Id: GH-6309, PR-6324

Erts 10.7.2.18

Fixed Bugs and Malfunctions

Fix bug where the process message queue was left in an inconsistent state when changing from on_heap to off_heap message queue data causing the GC to segfault.
Own Id: OTP-18075 Aux Id: PR-5927
Fix functions that convert universal to localtime (such as erlang:localtime/0 and erlang:universaltime_to_localtime/1) to fetch the correct localtime if it is changed after the start of the VM.
Own Id: OTP-18076 Aux Id: ERIERL-802 PR-5905
Fix memory leak when a process doing a distributed fragmented send is sent an exit signal. Before this fix the receiving node would be left with an incomplete message that would remain until the nodes were disconnected. The bug has existed since Erlang/OTP 21.
Own Id: OTP-18077 Aux Id: GH-5876 PR-5892

Erts 10.7.2.17

Fixed Bugs and Malfunctions

By default global does not take any actions to restore a fully connected network when connections are lost due to network issues. This is problematic for all applications expecting a fully connected network to be provided, such as for example mnesia, but also for global itself. A network of overlapping partitions might cause the internal state of global to become inconsistent. Such an inconsistency can remain even after such partitions have been brought together to form a fully connected network again. The effect on other applications that expects that a fully connected network is maintained may vary, but they might misbehave in very subtle hard to detect ways during such a partitioning.
In order to prevent such issues, we have introduced a prevent overlapping partitions fix which can be enabled using the prevent_overlapping_partitions kernel(6) parameter. When this fix has been enabled, global will actively disconnect from nodes that reports that they have lost connections to other nodes. This will cause fully connected partitions to form instead of leaving the network in a state with overlapping partitions. Note that this fix has to be enabled on all nodes in the network in order to work properly. Since this quite substantially changes the behavior, this fix is currently disabled by default. Since you might get hard to detect issues without this fix you are, however, strongly advised to enable this fix in order to avoid issues such as the ones described above. As of OTP 25 this fix will become enabled by default.
Own Id: OTP-17843 Aux Id: ERIERL-732, PR-5611
Fix memory leak when tracing on running on a process that only handle system tasks or non-message signals (for example process_info requests).
Own Id: OTP-17904 Aux Id: ERIERL-757
Fix Erlang monotonic time on MacOS. Previously used OS monotonic time primitive on MacOS is buggy and will not be used anymore. It has been replaced with usage of another OS monotonic time primitive that does not appear to be buggy.
Own Id: OTP-17998 Aux Id: PR-5825, GH-5554

Erts 10.7.2.16

Improvements and New Features

Responsiveness of processes executing on normal or low priority could suffer due to code purging or literal area removal on systems with a huge amount of processes. This since during these operations all processes on the system were scheduled for execution at once.
This problem has been fixed by introducing a limit on outstanding purge and copy literal requests in the system. By default this limit is set to twice the amount of schedulers on the system. This will ensure that schedulers will have enough work scheduled to perform these operations as quickly as possible at the same time as other work will be interleaved to a much higher degree. Performance of these operations will however be somewhat degraded due to the overhead of enforcing this limit compared to when using a very large limit.
This limit can be set by passing the +zosrl command line argument to erl, or by calling erlang:system_flag(outstanding_system_requests_limit, NewLimit).
Own Id: OTP-17796 Aux Id: ERIERL-729, PR-5473

Erts 10.7.2.15

Fixed Bugs and Malfunctions

The runtime system could call select() with a too large timeout value when executing on MacOS. This could in turn cause the runtime system to crash.
Own Id: OTP-17735 Aux Id: GH-5339
Certain distributed signals that for various reasons must to be forced into the distribution buffer even when it is full would instead be lost if the distribution buffer was full when sent. The effected signals:
- EXIT signals with exit reasons of one word size.
- DOWN signals with exit reasons of one word size.
- demonitor signals from a terminating process.
- unlink_ack signals on OTP 23 and 24.
- spawn_reply signals on OTP 23 and 24.
Own Id: OTP-17737 Aux Id: GH-5346, GH-4989

Erts 10.7.2.14

Fixed Bugs and Malfunctions

On 32-bit computers, binary_to_term/1,2 is now more resilient against corrupted binaries containing maps in the external format.
Own Id: OTP-17604
A call to process_info(Pid, status) could erroneously report the status running when it should have reported waiting. This occurred when the calling process was executing on a higher priority than the process being inspected. This bug has been present since OTP 21.0 (erts version 10.0).
Own Id: OTP-17628
A race between an exiting port and handling of simultaneously received signals to that port could cause a runtime system crash. The effected signals are link, monitor and demonitor. On OTP 22 a similar race could also cause a memory leak when receiving an unlink signal.
Own Id: OTP-17642 Aux Id: PR-5248
The message queue of a process entered an inconsistent state after a receive expression with an invalid timeout value was executed. If the exception raised due to the invalid timeout value was caught, the following receive expression executed by the process could fail to match messages already present in the message queue.
On OTP 24 this could also cause the whole runtime system to crash.
Own Id: OTP-17651 Aux Id: GH-5235, PR-5244
Sending a Port ! {PortOwner, close} signal from a process other than the port owner could erroneously trigger a badsig exit signal being sent to the port owner process even though the correct PortOwner had been passed in the signal.
Own Id: OTP-17665 Aux Id: PR-5248
This fixes a bug in erts_factory_undo that caused the heap to not be reset correctly. The erts_factory_undo function is, for example, called when a binary_to_term/1 call fails to reset the heap to its state before the binary_to_term/1 call. This can cause the heap to contain invalid terms which potentially can cause issues (e.g., crashes) when the whole heap is scanned.
Own Id: OTP-17677
Fix bug in persistent_term when a key-value pair contains a magic reference that is referred more than once. Magic references are NIF resources or returned from BIFs like ets:new, atomics:new. The bug could cause the memory of the referred resource to be prematurely deallocated.
The bug also apply to magic references in message passing on a runtime built with configure option --enable-sharing-preserving.
Bug exist for 64-bit since OTP-24.0 and for 32-bit since OTP-20.0.
Own Id: OTP-17700 Aux Id: GH-5271, PR-5273

Erts 10.7.2.13

Fixed Bugs and Malfunctions

Fixed a bug in zlib where decompression would crash with data_error on some valid inputs. The bug could also cause extraction from a zip archive using zip:extract() to fail.
Own Id: OTP-17470 Aux Id: ERIERL-657
A call to erlang:cancel_timer(_, [{info, false}]) could cause the calling process to block forever in the call. Note that only the synchronous version of the call (that is, the async option is false) in combination with the info option set to false was effected by this bug.
Own Id: OTP-17472 Aux Id: PR-4932
Microstate accounting (msacc) and os:perf_counter() unintentionally used system time instead of monotonic time for time measurements on a lot of systems. These systems were all non x86/x86_64 systems or x86/x86_64 systems without a reliable and constant rdtsc instruction.
The lock counting (lcnt) built runtime system also unintentionally used system time instead of monotonic time for time measurements on all systems.
Own Id: OTP-17493
Simultaneous calls to erlang:system_flag(schedulers_online, _) could cause callers to end up in a suspended state forever.
Own Id: OTP-17500 Aux Id: GH-4809
Fix rare race bug in memory management of distribution entries. Have been seen to cause VM crash when massive number of repeated concurrent failing connection attempts.
Own Id: OTP-17513 Aux Id: GH-4964, PR-5015
Fix buffer overrun problem in the tty driver. The problem happens on some platforms when using the CTRL+R functionality of newshell with very long strings in the history.
Own Id: OTP-17560 Aux Id: GH-5116
Fix race-condition that could cause a crash when tracing scheduling or garbage collections on a process that was running on a dirty scheduler.
Own Id: OTP-17568 Aux Id: PR-4940
Fix rare bug where re:run would crash/return invalid results when given a subbinary as subject.
This bug has existed since Erlang/OTP 20.0.
Own Id: OTP-17585 Aux Id: GH-5150
binary_to_term/1,2 is now more resilient against corrupted binaries containing maps in the external format.
Own Id: OTP-17594

Erts 10.7.2.12

Fixed Bugs and Malfunctions

A call to port_command() could cause a scheduler to end up in an eternal loop if the port was busy and the calling process had incoming signals at the time of the call. This bug was introduced in OTP 23.3.2 (ERTS version 11.2.1), OTP 22.3.4.18 (ERTS version 10.7.2.10), and OTP 21.3.8.23 (ERTS version 10.3.5.18).
Own Id: OTP-17448 Aux Id: GH-4898, PR-4903, OTP-17291

Erts 10.7.2.11

Fixed Bugs and Malfunctions

Fix bug in match spec compilator seen to cause a stack overflow crash on debug VM for certain match specs. Could potentially cause problems for standard VM, but has not been verified. Match specs are used by ets:match/select functions and erlang:trace_pattern.
Own Id: OTP-17379 Aux Id: PR-4804
Commit of generated configure script.
Own Id: OTP-17420 Aux Id: OTP-17398, GH-4821

Erts 10.7.2.10

Fixed Bugs and Malfunctions

The following signals could pass before other signals from the same sender to the same receiver. That is, these signals could arrive too early.
- garbage-collect request. Sent from one process to another using one of the garbage_collect/0 BIFs.
- check-process-code request. Sent from one process to another using one of the check_process_code() BIFs.
- is-process-alive reply. Sent as a response to a process calling the is_process_alive() BIF.
- process-info reply. Sent as a response to a process calling one of the process_info() BIFs.
- port-command reply. Sent as a response to a process calling one of the port_command() BIFs.
- port-connect reply. Sent as a response to a process calling the port_connect() BIF.
- port-close reply. Sent as a response to a process calling the port_close() BIF.
- port-control reply. Sent as a response to a process calling the port_control() BIF.
- port-call reply. Sent as a response to a process calling the port_call() BIF.
- port-info reply. Sent as a response to a process calling one of the port_info() BIFs.
Own Id: OTP-17291
A garbage collection of a literal area missed messages that entirely consisted of a term in a literal area. This could in turn lead to a crash of the runtime system.
Own Id: OTP-17307
A call to process_flag(message_queue_data, off_heap) could cause a crash of the runtime system when sequential tracing was enabled.
Own Id: OTP-17349

Erts 10.7.2.9

Fixed Bugs and Malfunctions

Fixed a bug in the timer implementation which could cause timers that were set to more than 37.25 hours in the future to be delayed. This could occur if there were multiple timers scheduled to be triggered very close in time, but still at different times, and the scheduler thread handling the timers was not able to handle them quickly enough. Delayed timers were in this case triggered when another unrelated timer was triggered.
Own Id: OTP-17253
Fix bug in call_time tracing (used by eprof) that could cause VM crash. Bug exists since OTP-22.2 (but not in OTP-23).
Own Id: OTP-17290 Aux Id: GH-4635

Improvements and New Features

Fix a file descriptor leak when using sendfile and the remote side closes the connection. This bug has been present since OTP-21.0.
Own Id: OTP-17244

Erts 10.7.2.8

Fixed Bugs and Malfunctions

Fixed a bug that could cause some work scheduled for execution on scheduler threads to be delayed until other similar work appeared. Beside delaying various cleanup of internal data structures also the following could be delayed:
- Termination of a distribution controller process
- Disabling of the distribution on a node
- Gathering of memory allocator information using the instrument module
- Enabling, disabling, and gathering of msacc information
- Delivery of 'CHANGE' messages when time offset is monitored
- A call to erlang:cancel_timer()
- A call to erlang:read_timer()
- A call to erlang:statistics(io | garbage_collection | scheduler_wall_time)
- A call to ets:all()
- A call to erlang:memory()
- A call to erlang:system_info({allocator | allocator_sizes, _})
- A call to erlang:trace_delivered()
The bug existed on runtime systems running on all types of hardware except for x86/x86_64.
Own Id: OTP-17185

Erts 10.7.2.7

Fixed Bugs and Malfunctions

The suspend_process() and resume_process() BIFs did not check their arguments properly which could cause an emulator crash.
Own Id: OTP-17080
The runtime system would get into an infinite loop if the runtime system was started with more than 1023 file descriptors already open.
Own Id: OTP-17088 Aux Id: ERIERL-580

Erts 10.7.2.6

Fixed Bugs and Malfunctions

Fixed rare distribution bug in race between received signal (link/monitor/spawn_request/spawn_reply) and disconnection. Symptom: VM crash. Since: OTP 21.0.
Own Id: OTP-16869 Aux Id: ERL-1337

Erts 10.7.2.5

Fixed Bugs and Malfunctions

Fixed bugs causing issues when enabling the ERTS internal allocators on a system built with the undocumented and unsupported SMALL_MEMORY feature.
Own Id: OTP-16939

Erts 10.7.2.4

Fixed Bugs and Malfunctions

inet:setopts([{active,once}]) wakes up IO polling thread unnecessarily, leading to lock contention and visibly higher CPU utilization.
Own Id: OTP-16847 Aux Id: ERL-1301
The documentation of statistics(run_queue) erroneously stated that it returns the total length of all normal run queues when it is the total length of all normal and dirty CPU run queues that is returned. The documentation has been updated to reflect the actual behavior.
Own Id: OTP-16866 Aux Id: ERL-1355
Two bugs in the ERTS internal thread wakeup functionality have been fixed. These bugs mainly hit when all threads in the system tried to go to sleep. When the bugs were triggered, certain operations were delayed until a thread woke up due to some other reason. Most important operations effected were code loading, persistent term updates, and memory deallocation.
Own Id: OTP-16870
Fixed bug in ets:select_replace/2 on compressed tables that could produce faulty results or VM crash. Bug exists since OTP 20.
Own Id: OTP-16874 Aux Id: ERL-1356, PR-2763

Improvements and New Features

As of OTP 22, the allocator specific memory carrier pools were replaced by a node global carrier pool. This unfortunately caused substantial memory fragmentation in some cases due to long lived data being spread into carriers used by allocators mainly handling short lived data.
A new command line argument +M<S>cp has been introduced with which one can enable the old behavior as well as configuring other behaviors for the carrier pools. In order to configure the old behavior, with allocator specific carrier pools for all allocators, pass +Mucp : (including the colon character) as a command line argument to erl when starting the Erlang system.
The default configuration for carrier pools will be changed to +Mucp : some time in the future, but not in this patch.
Own Id: OTP-16856

Erts 10.7.2.3

Fixed Bugs and Malfunctions

The ERTS internal I/O poll implementation could get into an inconsistent state causing input events to be ignored.
Own Id: OTP-16780 Aux Id: PR-2701

Erts 10.7.2.2

Fixed Bugs and Malfunctions

An unintentional reuse of an already used emulator internal event object could cause a wakeup signal to a thread to be lost. In worst case this could cause the runtime system to hang. This hang was however quite rare.
Own Id: OTP-16766 Aux Id: ERL-1304
NIF threads and driver threads on non-Linux systems leaked internal resources when terminating. On Windows these resources were one event per thread. On most other systems one mutex and one condition variable per thread. On these other systems that also lacked pthread_cond_timedwait() also a pipe with its file descriptors was leaked.
Own Id: OTP-16772 Aux Id: ERL-1304

Erts 10.7.2.1

Fixed Bugs and Malfunctions

Fixed bug in erl_crash.dump generation that could cause a SEGV core dump if a recently cancelled timer was found.
Own Id: OTP-16596 Aux Id: ERL-1105, PR-2606
The functionality utilized by BIFs for temporary disabling of garbage collection while yielding could cause system task queues to become inconsistent on a process executing such a BIF. Process system tasks are for example utilized when purging code, garbage collecting literal data, and when issuing an ordinary garbage collection from another process.
The bug does not trigger frequently. Multiple code purges in direct sequence makes it more likely that this bug is triggered. In the cases observed, this has resulted in a hanging code purge operation.
Own Id: OTP-16639 Aux Id: ERL-1236
SCTP and UDP recv/2,3 hangs indefinitely if socket is closed while recv is called (socket in passive mode).
Own Id: OTP-16654 Aux Id: ERL-1242

Erts 10.7.2

Fixed Bugs and Malfunctions

A literal area could prematurely be released before all uses of it had been removed. This occurred either when a terminating process had a complex exit reason referring to a literal that concurrently was removed, or when a terminating process continued executing a dirty NIF accessing a literal (via the heap) that concurrently was removed.
Own Id: OTP-16640 Aux Id: OTP-16193
The VM could potentially crash when checking process code of a process that terminated while executing a dirty NIF. The checking of process code is part of a code purge operation.
Own Id: OTP-16641
System tasks of low priority were not interleaved with normal priority system tasks as they should. This could potentially delay garbage collection of another process longer than intended if the garbage collection was requested from a low priority process.
Own Id: OTP-16642

Erts 10.7.1

Fixed Bugs and Malfunctions

[re:run(Subject, RE, [unicode])](re:run/3) returned nomatch instead of failing with a badarg error exception when Subject contained illegal utf8 and RE was passed as a binary. This has been corrected along with corrections of reduction counting in re:run() error cases.
Own Id: OTP-16553
Fixed a bug that could cause the emulator to crash when purging modules or persistent terms.
Own Id: OTP-16555 Aux Id: ERL-1188
Fixed a bug in a receive optimization. This could cause a receive not to match even though a matching message was present in the message queue. This bug was introduced in ERTS version 10.6 (OTP 22.2).
Own Id: OTP-16572 Aux Id: ERL-1199, OTP-16269

Erts 10.7

Fixed Bugs and Malfunctions

gen_udp:recv(S, N, 0) corrupted the internal state for the socket so after receive with {active, once} it always returned {error, timeout}, and wasted the received UDP packets. This bug has now been fixed.
Reported and pinpointed by Alexander Petrovsky.
Own Id: OTP-16059
The atom esock_atom_user and esock_atom_kernel was never actually created. This has now been corrected.
Own Id: OTP-16381
Fixed bug in socket module that could potentially lead to scheduler deadlocks.
Own Id: OTP-16384
Fix bug causing VM crash if down or stop callback of a NIF resource is called after the NIF module has been purged. The fix will postpone unloading until all such resource objects have been garbage collected.
Own Id: OTP-16399
Fixed bug in ets:update_counter/4, when called with an invalid UpdateOp and a Key that does not exist, causing ets:info(T,size) to return incorrect values. Bug exists since OTP-19.0.2.
Own Id: OTP-16404 Aux Id: ERL-1127
Fix potential heap corrupting bugs when a process calls a BIF that blocks other normal schedulers and then writes to its own heap without the main process lock. A NIF running on a dirty scheduler trying to interact with such a process could corrupt its heap. The fixed BIFs were related to code loading and tracing.
Own Id: OTP-16417
Fixed bug in erlang:list_to_ref/1 when called with a reference created by a remote note. Function list_to_ref/1 is intended for debugging and not to be used in application programs. Bug exist since OTP 20.0.
Own Id: OTP-16438
The prim_net nif (net/kernel) made use of an undefined atom, notsup. This has now been corrected.
Own Id: OTP-16440
Corrected the valid range of the erl command line argument +SDio <NumberOfDirtyIoSchedulers> from 0..1024 to 1..1024. +SDio 0 was erroneously allowed which just caused the VM to crash on the first dirty I/O job scheduled.
Own Id: OTP-16481
Fix a crash when attempting to log faults when loading files during early boot.
Own Id: OTP-16491

Improvements and New Features

For socket, not all send and receive flags are supported on all platforms. In order to (at least) simplify testing, the socket:supports/0,1,2,3 functions has been extended with send_flags and recv_flags items, which indicates what the current platform can manage.
Own Id: OTP-16153
Add a "full featured" version of getifaddrs in the net module.
Own Id: OTP-16212 Aux Id: ERL-1070
The options busy_limits_port and busy_limits_msgq have been added to the BIF erlang:open_port/2. The busy_limits_port option can be used for controlling the busy state of a port executing the spawn_driver or the fd_driver. The busy_limits_msgq option can be used for controlling the busy state of the port message queue.
Own Id: OTP-16306 Aux Id: ERIERL-439
A socket "registry" has been added making it possible to list current open sockets.
Own Id: OTP-16309
The counters managed by the socket nif has been extended. Their "size" has been increased from 32 bit to 64. Two max package size (for read and write) has been added. And four accept counters has been added.
Own Id: OTP-16387
Add gcc option -fno-common to detect accidental name clashes of global variables.
Own Id: OTP-16420 Aux Id: PR-2513
New dynamic lock checker that verifies locking orders and detects potential deadlock bugs in drivers and NIFs. Enabled together with the old static lock checker (for ERTS internal locks) in emulator started with -emu_type debug or built with configuration option --enable-lock-checking.
Own Id: OTP-16427

Erts 10.6.4

Fixed Bugs and Malfunctions

A process could get into an inconsistent state where it was runnable, but never scheduled for execution. This could occur when a mix of normal and low priority processes where scheduled on the same type of dirty scheduler simultaneously.
Own Id: OTP-16446 Aux Id: ERL-1157

Erts 10.6.3

Fixed Bugs and Malfunctions

A process could end up in a state where it got endlessly rescheduled without making any progress. This occurred when a system task, such as check of process code (part of a code purge), was scheduled on a high priority process trying to execute on a dirty scheduler.
Own Id: OTP-16436 Aux Id: ERL-1152

Improvements and New Features

Improved signal handling for processes executing dirty. For example, avoid busy wait in dirty signal handler process when process is doing garbage collection on dirty scheduler.
Own Id: OTP-16358

Erts 10.6.2

Fixed Bugs and Malfunctions

Taking a scheduler offline could cause timers set while executing on that scheduler to be delayed until the scheduler was put online again. This bug was introduced in ERTS version 10.0 (OTP 21.0).
Own Id: OTP-16371
The ets:update_counter/4 core dumped when given an ordered_set with write_concurrency enabled and an invalid position. This bug has been fixed.
Own Id: OTP-16378 Aux Id: ERL-1125
A process calling erlang:system_flag(multi_scheduling, block) could end up blocked waiting for the operation to complete indefinitely.
Own Id: OTP-16379

Improvements and New Features

Duplicate entries for [socket:]getopt and [socket:]setopt in man page.
Own Id: OTP-16333 Aux Id: ERL-1104

Erts 10.6.1

Fixed Bugs and Malfunctions

Corrected an issue with the new socket api which could cause a core dump. A race during socket close could cause a core dump (an invalid nif environment free).
Own Id: OTP-16314 Aux Id: ERL-1098
Corrected an issue with the new socket api which could cause a core dump. When multiple accept processes waiting for a connect a connect could cause a core dump.
Own Id: OTP-16359

Erts 10.6

Fixed Bugs and Malfunctions

The functions unicode:characters_to_list() and unicode:characters_to_binary() raised a badarg exception instead of returning an error tuple when passed very large invalid code points as input.
Own Id: OTP-16052
file:allocate/3 will now work properly on Mac OS.
Own Id: OTP-16074 Aux Id: ERL-1042, PR-2386
For socket, invalid encoding of send and receive flags caused badarg and send failure.
Own Id: OTP-16149
Fix a bug in re on platforms where the native stack grows upwards, for instance on HP PA-RISC.
Own Id: OTP-16150 Aux Id: ERL-1043
For socket, unable to properly decode the timestamp control message header on FreeBSD. We incorrectly used the SO_TIMESTAMP flag for the timestamp control message header type. It should have been SCM_TIMESTAMP. This caused the timestamp control message header to not be fully decoded.
Own Id: OTP-16151 Aux Id: #2400
For socket, when setting the ip option 'recvtos' to true, thereby indicating that we want to receive the TOS control message header, we don't actually get TOS but RECVTOS on FreeBSD (and maybe others)! This was previously not handled.
Own Id: OTP-16152 Aux Id: OTP-16114
Fixed a bug where the emulator would print out error messages forever if it crashed during startup.
Own Id: OTP-16159 Aux Id: ERL-1060
For socket, wrong type for protocol caused segmentation fault if protocol was provided as {raw, integer()}.
Own Id: OTP-16163 Aux Id: ERL-1061
For socket, when setting the ip option 'recvttl' to true, thereby indicating that we want to receive the TTL control message header, we don't actually get TTL but RECVTTL on Solaris (and maybe others)! This was previously not handled.
Own Id: OTP-16172 Aux Id: OTP-16114
For socket, IPv6 control message headers was incorrectly decoded with level ip instead of ipv6.
Own Id: OTP-16173
Fix configure bug where clock_getres would not correctly be detected causing erlang:system_info(os_system_time_source) to return an incorrect resolution.
This bug effects all OSs that use clock_gettime to get time (basically all OSs except windows) and has been present since OTP-19.2.
Own Id: OTP-16191 Aux Id: ERL-1067
Fix bugs when using ERLC_USE_SERVER=true on Windows when building Erlang/OTP.
Change the cookie used by the compile server to be hard coded instead of using the users cookie.
Own Id: OTP-16192
Fix so that persistent_term is listed in the erts application file.
Own Id: OTP-16194
Fix bug in call_time tracing which could sometimes cause call time measurements being attributed to the wrong function.
Own Id: OTP-16195 Aux Id: ERL-1027
The socket socket option 'peek_off' has been disabled. If peek_off was set and then socket:recv/3 was called with the peek flag, the call could hang.
Own Id: OTP-16196
Handle possibly uninitiated (control message header) data.
Own Id: OTP-16197
For net, a couple of NI macros was deprecated in new versions of glibc, so these are no longer used (IDN_ALLOW_UNASSIGNED and IDN_USE_STD3_ASCII_RULES).
Own Id: OTP-16203
The string value from a get operation needed to be truncated.
Own Id: OTP-16204
Fix misleading seq_trace message for remote send operation toward named process. Changed receiver to be {Name,Node} instead of just Name.
Own Id: OTP-16206 Aux Id: PR-2423
Fixed a bug causing actual nodedown reason reported by net_kernel:monitor_nodes(true, [nodedown_reason]) to be lost and replaced by the reason killed.
Own Id: OTP-16216
For socket, the timestamp creation used when printing warning messages and debug printouts did not work. The used buffer was too small.
Own Id: OTP-16223
Fix compiler warnings generated by GCC 8
Own Id: OTP-16235
Fix erl -emu_type to accept the option opt which means the normal optimized emulator. This can be used to override the -emu_type option from environment variables.
Own Id: OTP-16297
Corrected the function spec to reflect the actual code of the function socket:bind.
Own Id: OTP-16310 Aux Id: ERL-1082
Fixed a performance issue in ETS lookup when using the compressed option and the term contained atoms. Before this fix the decompress algorithm for atoms would unnecessarily take a global lock to validate the atom.
Own Id: OTP-16316

Improvements and New Features

For socket, not all send and receive flags are supported on all platforms. In order to (at least) simplify testing, the socket:supports/0,1,2,3 functions has been extended with send_flags and recv_flags items, which indicates what the current platform can manage.
Own Id: OTP-16153
For socket, add support for IPv6 socket options tclass and recvtclass. Both has been added, but the use of them are platform dependent. Call socket:supports(options, ipv6, Opt) to be sure what option to use in order to request a TCLASS control message header.
Own Id: OTP-16180
For socket, the TCP socket option cork was not supported even though the supports function reported it as such.
Own Id: OTP-16205
The Kernel application's User's Guide now contain a Logger Cookbook with common usage patterns.
Own Id: OTP-16208
Add a "full featured" version of getifaddrs in the net module.
Own Id: OTP-16212 Aux Id: ERL-1070
Fix an inefficiency introduced by the bug fix in OTP-16241 which fixed a problem with the receive optimization. That bug fix introduced an inefficiency when using the receive optimization and a burst of messages arrive at once when the receiving process' mailbox was empty.
Own Id: OTP-16269 Aux Id: OTP-16241
For socket, added support for the socket option extended_err. Andreas Schultz.
Own Id: OTP-16302 Aux Id: #2449
ETS tables have been optimized to not use any locks when running in a system with only one scheduler enabled. This can provide significant performance gains for applications that use ETS tables heavily.
Own Id: OTP-16315

Erts 10.5.6

Fixed Bugs and Malfunctions

Large amounts of quickly executed dirty work could cause heavy contention on an internal spin lock. The spin lock was replaced by a mutex which behaves much better under these conditions.
Own Id: OTP-16301 Aux Id: ERL-1079

Erts 10.5.5

Fixed Bugs and Malfunctions

A literal area could prematurely be released before all uses of it had been removed. This occurred either when a terminating process had a complex exit reason referring to a literal that concurrently was removed, or when a terminating process continued executing a dirty NIF accessing a literal (via the heap) that concurrently was removed.
Own Id: OTP-16193
Fix bug causing VM crash due to memory corruption of distribution entry. Probability of crash increases if Erlang distribution is frequently disconnected and reestablished towards same node names. Bug exists since OTP-21.0.
Own Id: OTP-16224 Aux Id: ERL-1044
Fixed bug causing crash of VM built with configuration --enable--sharing-preserving. Provoked when a sent message contains both a bit string and the heap binary (< 65 bytes) which the bit string was matched from. Bug exists since OTP-19.0 but has seen to be easier to provoke since OTP-22.1.
Own Id: OTP-16265 Aux Id: ERL-1064

Erts 10.5.4

Fixed Bugs and Malfunctions

The compiler could do an unsafe optimization of receives, which would cause a receive to only scan part of the message queue.
This bug fix in the compiler fixes a bug in the socket module.
Own Id: OTP-16219 Aux Id: ERL-1076
Fix bug where the receive marker used by the runtime to do the receive queue optimization could be incorrectly set. The symptom of this would be that a message that should match in a receive never matches.
The bug requires the OTP-22 compiler and multiple selective receives to trigger. See OTP-16219 for details about the bug fix in the compiler.
Own Id: OTP-16241 Aux Id: ERL-1076 OTP-16219

Erts 10.5.3

Fixed Bugs and Malfunctions

Erlang/OTP can now be built on macOS Catalina (10.15).
Own Id: OTP-16177 Aux Id: ERL-1063

Erts 10.5.2

Improvements and New Features

Added the environment variable ERLC_SERVER_ID, which allows multiple compile servers to run separately under the same user.
Own Id: OTP-16125 Aux Id: ERIERL-412

Erts 10.5.1

Fixed Bugs and Malfunctions

A terminating process sending distributed 'EXIT' or 'DOWN' signals while terminating could end up in a state where no progress at all was made. This was triggered by a distribution channel that the terminating process was sending on got busy. This bug has existed since ERTS version 10.4 (OTP 22.0).
Own Id: OTP-16069
When communicating with a simultaneously exiting port via the erlang:port_*() BIFs one could sometimes get stray {Ref, What} messages. Where Ref was a reference and What usually were the atom badarg.
Own Id: OTP-16107 Aux Id: ERL-1049

Erts 10.5

Fixed Bugs and Malfunctions

If you set {linger,{true,0}} on a gen_tcp listen socket, accept a connection on that socket, and then close the accepted socket, now the linger zero setting is transferred to the accepted socket. Before this correction that information was lost and the close behaviour on the accepted socket incorrect.
Own Id: OTP-15370 Aux Id: ERIERL-353
Sending ancillary data implemented in OTP-15747 accidentally left behind test code that caused all UDP sends to fail on Windows. This has now been fixed.
Own Id: OTP-15422 Aux Id: OTP-15747
In the socket nif, used invalid flags when if-def'ing for supported TCP flags: TCP_MAXSEG and TCP_NODELAY (the support function).
Own Id: OTP-15827
Fixed memory leaks in experimental socket module.
Own Id: OTP-15830
re:run() now yields when validating utf8 in a large subject.
Own Id: OTP-15836 Aux Id: ERL-876
Fixed bug in seq_trace:set_token(label,Term) which could cause VM crash if Term was heap allocated (not an atom, small integer, local pid or port). Bug exists since OTP 21.0 when terms other than small integers were first allowed as labels.
Own Id: OTP-15849 Aux Id: ERL-700
Extra -mode flags given to erl are ignored with a warning.
Own Id: OTP-15852
Don't loop indefinitely when --enable-pgo is given to configure, but compiler does not support pgo.
Own Id: OTP-15853 Aux Id: PR-2254
Fix seq_trace:print/2 not to raise badarg exception if label is not a small integer. Bug exists since OTP 21.0.
Own Id: OTP-15859 Aux Id: ERL-700
Fixed hipe_flush_icache_range for non-Linux OS on ARM.
Own Id: OTP-15874 Aux Id: ERL-958, PR-2266
The fix in OTP-15871 was too conservative and disabled the offending load-time optimization in some cases where it was safe.
Own Id: OTP-15881
Upgraded the ERTS internal PCRE library from version 8.42 to version 8.43. See http://pcre.org/original/changelog.txt for information about changes made to PCRE. This library implements major parts of the re regular expressions module.
Own Id: OTP-15889
Fix race condition when closing a socket while using {active,N} on Windows.
Own Id: OTP-15901 Aux Id: ERL-960 PR-2272
Allow more than one -config command line option to erl on Windows to conform with other OS.
Own Id: OTP-15918 Aux Id: ERL-912
Fix so that ERL_FLAGS environment variable does not interfere with command line arguments. Before this fix you could write:
ERL_FLAGS="10" erl +S
and erlang would start as if +S had been given the argument 10.
Own Id: OTP-15931
The bug with ID ERL-717 has been fixed. The functions io:columns() and io:rows() only worked correctly inside interactive erlang shells before this fix. These functions returned {error,enotsup} before this fix even if stdout and stdin were connected to a terminal when they were invoked from an escript or a program started with e.g., erl -noshell.
Own Id: OTP-15959 Aux Id: ERL-717
Do not use named label in ethread.c inline assemble. This allows erts to be compiled using gcc 9.1.0 with LTO enabled.
Own Id: OTP-15971 Aux Id: PR-2333
erlang:fun_to_list/1 will now escape the module and function name when necessary.
Own Id: OTP-15975 Aux Id: ERL-1009
process_info(P,binary) would neglect to look through heap fragments, potentially missing a few binaries associated with the process.
Own Id: OTP-15978 Aux Id: ERIERL-366
HiPE is now automatically disabled on systems with non-glibc implementation (for instance musl). This is because musl does not provide the API's for guaranteeing that signals are delivered on the correct native stack.
Own Id: OTP-16037
Fixed bug triggered if a process is killed during call to persistent_term:put or persistent_term:erase.
Own Id: OTP-16041
Add units to all memory slogans in the crash dump documentation.
Own Id: OTP-16042
Fix a bug in binary_to_term that would crash the emulator if a term larger than 16GB was to be decoded.
Own Id: OTP-16058 Aux Id: PR-2382
Fixed bug related to an exiting process sending EXIT and DOWN signals to remote linked/monitored processes. Bugs exists since OTP 22.0.
Own Id: OTP-16060

Improvements and New Features

erlc can now automatically use a compile server to avoid starting an Erlang system for each file to be compiled in a multi-file project. See the documentation for how to enable it.
Own Id: OTP-15738 Aux Id: PR-2361
The possibility to send ancillary data, in particular the TOS field, has been added to gen_udp:send/4,5.
Own Id: OTP-15747 Aux Id: ERIERL-294
The net module has been split into 'net' (kernel) and prim_net (preloaded).
Own Id: OTP-15765
Socket counters now works as expected and can also be extracted with the (new) info function.
Own Id: OTP-15818
re:run() now avoids validating utf8 in the subject more than once in the same call. This validation could previously be performed multiple times when the global option was passed.
Own Id: OTP-15831 Aux Id: ERL-876
The un-documented function erlang:dist_get_stat/1 now returns the real value of what the distribution queue contains instead of a boolean.
Own Id: OTP-15905 Aux Id: PR-2270
ETS ordered_set tables with write_concurrency enabled has got a performance issue fixed. There were no limits for the values of internal statistics counters before this fix. This could result in that the data structure sometimes reacted slowly to a change in how many parallel processes were using it.
Own Id: OTP-15906
Optimize the reception of large distribution messages.
Own Id: OTP-15926 Aux Id: PR-2291
Binary matching and functions like split_binary/2 will now create heap binaries when the results are small enough, reducing the chances of small sub-binaries keeping large binaries alive.
Own Id: OTP-15977 Aux Id: ERIERL-366
Fixed rare emulator crash in instrument:allocations/0-1.
Own Id: OTP-15983
Ports could pass very small binaries as reference counted off heap binaries to processes. This could cause an unnecessary large memory usage and an unnecessary load on the binary allocator. Small binaries are now always passed as heap binaries to processes.
Own Id: OTP-16001 Aux Id: ERIERL-366
unicode:characters_to_binary() could return very small binaries as reference counted off heap binaries. This could cause an unnecessary large memory usage and an unnecessary load on the binary allocator. Small binaries are now always returned as heap binaries.
Own Id: OTP-16002 Aux Id: ERIERL-366
Improved erl_nif documentation regarding on_load and Erlang stub/fallback functions.
Own Id: OTP-16028 Aux Id: PR-2362
New feature ets:info(_, binary) to get information about all reference counted binaries kept by a table. This is the same kind of debug information that process_info(_, binary) returns for a process.
Own Id: OTP-16035 Aux Id: ERIERL-366

Erts 10.4.4

Fixed Bugs and Malfunctions

An invalid value test caused the socket:setopt(Socket, ip, add_membership, ip_mreq()) to fail with badarg. The same for drop_membership.
Own Id: OTP-15908 Aux Id: ERL-980
Fixed bug causing VM crash when doing textual dump of a process containing an unhandled monitor down signal. Textual process dumps can be done with erlang:system_info(procs), trace feature process_dump, Erlang shell break menu and a crashdump. Bug exist since OTP 21.0.
Own Id: OTP-15909 Aux Id: ERL-979
lists:subtract/2 would produce incorrect results for some inputs on 64-bit platforms.
Own Id: OTP-15938 Aux Id: ERL-986
Fixed a bug in the loader that was similar to OTP-15938, yielding incorrect code for some inputs on 64-bit platforms.
Own Id: OTP-15939
Fixed bug causing scheduler threads in rare cases to block spinnning indefinitely. Bug exists since OTP 21.0.
Own Id: OTP-15941 Aux Id: PR-2313

Erts 10.4.3

Fixed Bugs and Malfunctions

Fixed a buffer overflow when binary_to_existing_atom/2 and list_to_existing_atom/2 was used with the latin1 encoding.
Own Id: OTP-15819 Aux Id: ERL-944
The runtime system disconnected a connection if it received an exit/2 signal where the recipient was a process on an old incarnation of the current node. That is, the receiving node had the same node name, but another "creation" number. The signal will now just be dropped since the receiving process no longer exists.
Own Id: OTP-15867 Aux Id: ERIERL-373

Erts 10.4.2

Fixed Bugs and Malfunctions

Fixed process_info(Pid,reductions) to not categorically increase reduction count of the measured process Pid. Repeated reduction measure of an idle process will most often (but not guaranteed) return the same value, like it behaved before OTP 21.3.8.
Own Id: OTP-15865 Aux Id: ERL-964
Fixed an incorrect load-time optimization that could cause a crash when extracting deeply nested tuple elements.
Own Id: OTP-15871 Aux Id: ERIERL-374
Fix bug causing VM crash when pressing P for "proc info" in Erlang shell break menu. Bug exists since OTP 22.0.
Own Id: OTP-15873 Aux Id: ERL-965

Erts 10.4.1

Fixed Bugs and Malfunctions

In nested use of try/catch, rethrowing an exception using erlang:raise/3 with a different class would not always be able to change the class of the exception.
Own Id: OTP-15834 Aux Id: ERIERL-367

Erts 10.4

Fixed Bugs and Malfunctions

Do not allocate new bitstring/binary when an empty binary is appended.
Own Id: OTP-15535 Aux Id: PR-2055
Document that process_info(_, current_function) can return {current_function, undefined} in case of execution of native code.
Own Id: OTP-15543 Aux Id: PR-2089
Fixed bug in ets:select, ets:match and friends which could cause the table to remain fixated (as if ets:safe_fixtable had been called) after the call returned. This could happen for protected tables if another concurrent running process transferred table ownership to the process during its ets:select/match call. Ownership can be transferred using either ets:give_away or the heir table option.
Own Id: OTP-15672
Fixed a Windows-specific bug in file:list_dir/1 that caused it to misbehave on network shares.
Own Id: OTP-15693
Fixed bug when calling enif_whereis_* from NIF resource destructor. Symptoms could be emulator crash or hanging scheduler threads.
Own Id: OTP-15694 Aux Id: ERL-863
Fixed a bug in the error case of apply/3, where the exception would erroneously have an empty argument list in some cases.
Own Id: OTP-15698
A bug has been fixed in the maps implementation that could cause a crash or memory usage to grow until the machine ran out of memory. This could happen when inserting a new key-value pair with a key K1 containing a binary B1 into a map M having a key K2 with a binary B2 if the following conditions were met:
- B1 =/= B2
- size(B1) >= 4294967296
- size(B2) >= 4294967296
- size(M) >= 32
- (size(B1) rem 4294967296) == (size(B2) rem 4294967296)
- the first (size(B1) rem 4294967296) bytes are the same both in B1 and B2
- substituting B1 in K1 with B2 would create a term with the same value as K2
The root cause of the problem is that the maps implementation only hashed the first (X rem 4294967296) bytes of binaries so that different binaries could get the same hash value independently of the hash seed.
Own Id: OTP-15707
term_to_binary() and distributed sends will now throw a system_limit exception instead of producing erroneous results when trying to encode a binary larger than 4 GB.
Own Id: OTP-15708
The vxworks configure has been updated to respect the environment CFLAGS.
Own Id: OTP-15773
Fix configure to not enable PGO (profile guided optimizations) when linking of the PGO binary fails. For instance this happens when there is no gcov lib installed.
Own Id: OTP-15788
Fix bug on OpenBSD where sockets using active, true or active, N could cause the system to live lock. The bug was introduced in erts-10.2 (OTP-21.2).
Own Id: OTP-15791

Improvements and New Features

Add support for Erlang Distribution protocol to split the payload of large signals into several fragments. This allows other processes to communicate uninterrupted during the transmission of these signals.
Own Id: OTP-13397
A simple socket API is provided through the socket module. This is a low level API that does not replace gen_[tcp|udp|sctp]. It is intended to eventually replace the inet driver, but not the high level gen-modules (gen_tcp, gen_udp and gen_sctp). It also provides a basic API that facilitates the implementation of other protocols, that is TCP, UDP and SCTP.
Known issues are; No support for the Windows OS (currently).
Own Id: OTP-14831
Added NIF functions enif_set_pid_undefined, enif_is_pid_undefined and enif_compare_pids.
Own Id: OTP-15011 Aux Id: PR-2147
Underutilized memory segments (carriers) can now move between all allocator instances, rather than just between instances of the same type, which greatly reduces memory usage in some scenarios.
Own Id: OTP-15063
The emulator will now mark free blocks in pooled carriers with madvise(2) + MADV_FREE (or similar), letting the OS reclaim the associated physical memory if necessary.
Own Id: OTP-15075
New ERL_NIF_SELECT_CANCEL feature added to enif_select in order to cancel (or "deselect") a read or write event on a previously selected file descriptor.
Own Id: OTP-15095
ETS option write_concurrency now also affects and improves the scalability of ordered_set tables. The implementation is based on a data structure called contention adapting search tree, where the lock granularity adapts to the actual amount of concurrency exploited by the applications in runtime.
Own Id: OTP-15128
Build configuration of the crypto application has been moved from the erts application into the crypto application.
Own Id: OTP-15129
Anonymous functions that don't capture environment are now created at load-time instead of in run-time.
Own Id: OTP-15195 Aux Id: PR-1812
Optimize updates of maps with identical keys and values. E.g. in the example below the original Map will be reused as the return of the update.
1> Map = #{ a => b }. #{ a => b } 2> Map#{ a := b }.
Own Id: OTP-15211 Aux Id: PR-1889
Optimize binary:match/2 and binary:matches/2 to use memchr internally.
Own Id: OTP-15238 Aux Id: PR-1803
The runtime system used to terminate when a message larger than 2 Gb was passed over the distribution. The send operation will now instead throw a system_limit exception.
Own Id: OTP-15261
Change the first module called by erts to be named erl_init instead of otp_ring0. systools in sasl have been updated to reflect this change.
Own Id: OTP-15336 Aux Id: PR-1825
Minor adjustments made to build system for parallel configure.
Own Id: OTP-15340 Aux Id: OTP-14625
Two new NIF interface functions enif_select_read and enif_select_write. They are similar to existing enif_select but allow a custom event message as an argument.
Own Id: OTP-15349 Aux Id: PR-2084
The embedded copy of zlib has been updated from 1.2.8 to 1.2.11.
Note that this copy is only used as a fallback when the target platform doesn't provide any zlib development libraries. If your system provides zlib then it will be used even if it is older than 1.2.11.
Own Id: OTP-15351 Aux Id: ERL-749
New NIF function enif_make_monitor_term.
Own Id: OTP-15362 Aux Id: PR-2127
Appending lists (The ++ operator) will now yield properly on large inputs.
Own Id: OTP-15427
The length/1 BIF used to calculate the length of the list in one go without yielding, even if the list was very long. In OTP 22, length/1 will yield when called with long lists.
Own Id: OTP-15439
Processes sending messages are now punished with a reduction cost based on message size. That is, a process sending a large message will yield earlier than before.
Own Id: OTP-15513 Aux Id: ERL-773
The transitory emulator option +ztma true (introduced in OTP 21.3) has been removed.
Own Id: OTP-15581 Aux Id: OTP-15580
In OTP 22, HiPE (the native code compiler) is not fully functional. The reasons for this are:
There are new BEAM instructions for binary matching that the HiPE native code compiler does not support.
The new optimizations in the Erlang compiler create new combination of instructions that HiPE currently does not handle correctly.
If erlc is invoked with the +native option, and if any of the new binary matching instructions are used, the compiler will issue a warning and produce a BEAM file without native code.
Own Id: OTP-15596
The termination behaviour of processes has changed to allow processes to yield while sending link exit/monitor down signals.
The erl crash dump has been expanded to now also include processes that are termeinating but have not yet terminated.
Own Id: OTP-15610
The dist messages EXIT, EXIT2 and MONITOR_DOWN have been updated with new versions that send the reason term as part of the payload of the message instead of as part of the control message.
The old versions are still present and can be used when communicating with nodes that don't support the new versions.
Own Id: OTP-15611
When sending messages, exit, exit2 and monitor down distributed signals, the process sending will now yield appropriately.
This means that a terminating process will yield and possibly be suspended on busy distribution entries while they are terminating. This means that any memory held by such processes will not be released until after all exit/monitor down signals have been sent.
Own Id: OTP-15612
All external pids/ports/refs created by erlang:list_to_pid/port/ref debug functions now compare equal to any other pid/port/ref with the same number from that node.
Before this change they compared differently because the node creation of the pid/port/ref did not compare equal to any real pid/port/ref creation.
This will mostly effect pids/ports/refs typed in the shell.
Own Id: OTP-15613
The persistent_term functions put/2 and erase/1 are now yielding.
Own Id: OTP-15615
A new erlang:dist_ctrl_set_opt(DHandle, get_size, Value) option has been added. This option makes it possible to configure the distribution channel identified by DHandle so that erlang:dist_ctrl_get_data(DHandle) also returns the size of the data to pass over the channel.
Own Id: OTP-15617
Previously, all ETS tables used centralized counter variables to keep track of the number of items stored and the amount of memory consumed. These counters can cause scalability problems (especially on big NUMA systems). This change adds an implementation of a decentralized counter and modifies the implementation of ETS so that ETS tables of type ordered_set with write_concurrency enabled use the decentralized counter. Experiments indicate that this change substantially improves the scalability of ETS ordered_set tables with write_concurrency enabled in scenarios with frequent ets:insert/2 and ets:delete/2 calls.
Own Id: OTP-15623 Aux Id: PR-2190
The iolist_size/1 function is now yielding which means that an Erlang/OTP system will be responsive even if the applications running on the system frequently call iolist_size/1 with large iolists.
Own Id: OTP-15631
A simple test suite for the net module has been added.
Own Id: OTP-15635
Added the NIF function enif_term_type, which helps avoid long sequences of enif_is_xyz by returning the type of the given term. This is especially helpful for NIFs that serialize terms, such as JSON encoders, where it can improve both performance and readability.
Own Id: OTP-15640
The last call optimization is now applied to BIFs. When calling a BIF in the tail position of a function, the return address and stack frame will now be discarded before calling the BIF. As a consequence of this change, the immediate caller of a tail-called BIF will no longer be available in stack backtraces.
Own Id: OTP-15674 Aux Id: PR-2177
Fix GC bug where distributed messages in a processes mailbox would cause extra GCs. This can be very expensive if there many messages in the mailbox.
Own Id: OTP-15703
Internal documentation has now been added to the Erts and Compiler applications.
The internal documents for Erts describe miscellaneous interesting implementation details. Those details can change at any time.
The internal documentation for Compiler documents the API for the Core Erlang modules. While we will not change those APIs without good reason, we don't give the same guarantees about backward compatibility as for the rest of the APIs in OTP.
Own Id: OTP-15715
The performance of non-bignum integer arithmetic has been improved.
Own Id: OTP-15740
The -remsh option to erl now automatically adds the local systems hostname to the target node if no nodename is given. e.g.
erl -name foo -remsh bar
erl -sname foo -remsh bar
Own Id: OTP-15794 Aux Id: PR-2219

Erts 10.3.5.19

Fixed Bugs and Malfunctions

Fix bug in match spec compilator seen to cause a stack overflow crash on debug VM for certain match specs. Could potentially cause problems for standard VM, but has not been verified. Match specs are used by ets:match/select functions and erlang:trace_pattern.
Own Id: OTP-17379 Aux Id: PR-4804
A call to port_command() could cause a scheduler to end up in an eternal loop if the port was busy and the calling process had incoming signals at the time of the call. This bug was introduced in OTP 23.3.2 (ERTS version 11.2.1), OTP 22.3.4.18 (ERTS version 10.7.2.10), and OTP 21.3.8.23 (ERTS version 10.3.5.18).
Own Id: OTP-17448 Aux Id: GH-4898, PR-4903, OTP-17291

Erts 10.3.5.18

Fixed Bugs and Malfunctions

The following signals could pass before other signals from the same sender to the same receiver. That is, these signals could arrive too early.
- garbage-collect request. Sent from one process to another using one of the garbage_collect/0 BIFs.
- check-process-code request. Sent from one process to another using one of the check_process_code() BIFs.
- is-process-alive reply. Sent as a response to a process calling the is_process_alive() BIF.
- process-info reply. Sent as a response to a process calling one of the process_info() BIFs.
- port-command reply. Sent as a response to a process calling one of the port_command() BIFs.
- port-connect reply. Sent as a response to a process calling the port_connect() BIF.
- port-close reply. Sent as a response to a process calling the port_close() BIF.
- port-control reply. Sent as a response to a process calling the port_control() BIF.
- port-call reply. Sent as a response to a process calling the port_call() BIF.
- port-info reply. Sent as a response to a process calling one of the port_info() BIFs.
Own Id: OTP-17291
A garbage collection of a literal area missed messages that entirely consisted of a term in a literal area. This could in turn lead to a crash of the runtime system.
Own Id: OTP-17307
A call to process_flag(message_queue_data, off_heap) could cause a crash of the runtime system when sequential tracing was enabled.
Own Id: OTP-17349

Erts 10.3.5.17

Fixed Bugs and Malfunctions

Fixed a bug in the timer implementation which could cause timers that were set to more than 37.25 hours in the future to be delayed. This could occur if there were multiple timers scheduled to be triggered very close in time, but still at different times, and the scheduler thread handling the timers was not able to handle them quickly enough. Delayed timers were in this case triggered when another unrelated timer was triggered.
Own Id: OTP-17253

Improvements and New Features

Fix a file descriptor leak when using sendfile and the remote side closes the connection. This bug has been present since OTP-21.0.
Own Id: OTP-17244

Erts 10.3.5.16

Fixed Bugs and Malfunctions

Fixed a bug that could cause some work scheduled for execution on scheduler threads to be delayed until other similar work appeared. Beside delaying various cleanup of internal data structures also the following could be delayed:
- Termination of a distribution controller process
- Disabling of the distribution on a node
- Gathering of memory allocator information using the instrument module
- Enabling, disabling, and gathering of msacc information
- Delivery of 'CHANGE' messages when time offset is monitored
- A call to erlang:cancel_timer()
- A call to erlang:read_timer()
- A call to erlang:statistics(io | garbage_collection | scheduler_wall_time)
- A call to ets:all()
- A call to erlang:memory()
- A call to erlang:system_info({allocator | allocator_sizes, _})
- A call to erlang:trace_delivered()
The bug existed on runtime systems running on all types of hardware except for x86/x86_64.
Own Id: OTP-17185

Erts 10.3.5.15

Fixed Bugs and Malfunctions

Fixed rare distribution bug in race between received signal (link/monitor/spawn_request/spawn_reply) and disconnection. Symptom: VM crash. Since: OTP 21.0.
Own Id: OTP-16869 Aux Id: ERL-1337
The suspend_process() and resume_process() BIFs did not check their arguments properly which could cause an emulator crash.
Own Id: OTP-17080
The runtime system would get into an infinite loop if the runtime system was started with more than 1023 file descriptors already open.
Own Id: OTP-17088 Aux Id: ERIERL-580

Erts 10.3.5.14

Fixed Bugs and Malfunctions

The ERTS internal I/O poll implementation could get into an inconsistent state causing input events to be ignored.
Own Id: OTP-16780 Aux Id: PR-2701
The documentation of statistics(run_queue) erroneously stated that it returns the total length of all normal run queues when it is the total length of all normal and dirty CPU run queues that is returned. The documentation has been updated to reflect the actual behavior.
Own Id: OTP-16866 Aux Id: ERL-1355
Two bugs in the ERTS internal thread wakeup functionality have been fixed. These bugs mainly hit when all threads in the system tried to go to sleep. When the bugs were triggered, certain operations were delayed until a thread woke up due to some other reason. Most important operations effected were code loading, persistent term updates, and memory deallocation.
Own Id: OTP-16870
Fixed bug in ets:select_replace/2 on compressed tables that could produce faulty results or VM crash. Bug exists since OTP 20.
Own Id: OTP-16874 Aux Id: ERL-1356, PR-2763

Erts 10.3.5.13

Fixed Bugs and Malfunctions

An unintentional reuse of an already used emulator internal event object could cause a wakeup signal to a thread to be lost. In worst case this could cause the runtime system to hang. This hang was however quite rare.
Own Id: OTP-16766 Aux Id: ERL-1304
NIF threads and driver threads on non-Linux systems leaked internal resources when terminating. On Windows these resources were one event per thread. On most other systems one mutex and one condition variable per thread. On these other systems that also lacked pthread_cond_timedwait() also a pipe with its file descriptors was leaked.
Own Id: OTP-16772 Aux Id: ERL-1304

Erts 10.3.5.12

Fixed Bugs and Malfunctions

The functionality utilized by BIFs for temporary disabling of garbage collection while yielding could cause system task queues to become inconsistent on a process executing such a BIF. Process system tasks are for example utilized when purging code, garbage collecting literal data, and when issuing an ordinary garbage collection from another process.
The bug does not trigger frequently. Multiple code purges in direct sequence makes it more likely that this bug is triggered. In the cases observed, this has resulted in a hanging code purge operation.
Own Id: OTP-16639 Aux Id: ERL-1236
A literal area could prematurely be released before all uses of it had been removed. This occurred either when a terminating process had a complex exit reason referring to a literal that concurrently was removed, or when a terminating process continued executing a dirty NIF accessing a literal (via the heap) that concurrently was removed.
Own Id: OTP-16640 Aux Id: OTP-16193
The VM could potentially crash when checking process code of a process that terminated while executing a dirty NIF. The checking of process code is part of a code purge operation.
Own Id: OTP-16641
System tasks of low priority were not interleaved with normal priority system tasks as they should. This could potentially delay garbage collection of another process longer than intended if the garbage collection was requested from a low priority process.
Own Id: OTP-16642

Erts 10.3.5.11

Fixed Bugs and Malfunctions

[re:run(Subject, RE, [unicode])](re:run/3) returned nomatch instead of failing with a badarg error exception when Subject contained illegal utf8 and RE was passed as a binary. This has been corrected along with corrections of reduction counting in re:run() error cases.
Own Id: OTP-16553
Fixed a bug that could cause the emulator to crash when purging modules or persistent terms.
Own Id: OTP-16555 Aux Id: ERL-1188

Erts 10.3.5.10

Fixed Bugs and Malfunctions

Fixed bug in ets:update_counter/4, when called with an invalid UpdateOp and a Key that does not exist, causing ets:info(T,size) to return incorrect values. Bug exists since OTP-19.0.2.
Own Id: OTP-16404 Aux Id: ERL-1127
A process could get into an inconsistent state where it was runnable, but never scheduled for execution. This could occur when a mix of normal and low priority processes where scheduled on the same type of dirty scheduler simultaneously.
Own Id: OTP-16446 Aux Id: ERL-1157
Corrected the valid range of the erl command line argument +SDio <NumberOfDirtyIoSchedulers> from 0..1024 to 1..1024. +SDio 0 was erroneously allowed which just caused the VM to crash on the first dirty I/O job scheduled.
Own Id: OTP-16481

Erts 10.3.5.9

Fixed Bugs and Malfunctions

A process could end up in a state where it got endlessly rescheduled without making any progress. This occurred when a system task, such as check of process code (part of a code purge), was scheduled on a high priority process trying to execute on a dirty scheduler.
Own Id: OTP-16436 Aux Id: ERL-1152
Fixed bug in erlang:list_to_ref/1 when called with a reference created by a remote note. Function list_to_ref/1 is intended for debugging and not to be used in application programs. Bug exist since OTP 20.0.
Own Id: OTP-16438

Erts 10.3.5.8

Fixed Bugs and Malfunctions

Taking a scheduler offline could cause timers set while executing on that scheduler to be delayed until the scheduler was put online again. This bug was introduced in ERTS version 10.0 (OTP 21.0).
Own Id: OTP-16371
A process calling erlang:system_flag(multi_scheduling, block) could end up blocked waiting for the operation to complete indefinitely.
Own Id: OTP-16379

Erts 10.3.5.7

Fixed Bugs and Malfunctions

A literal area could prematurely be released before all uses of it had been removed. This occurred either when a terminating process had a complex exit reason referring to a literal that concurrently was removed, or when a terminating process continued executing a dirty NIF accessing a literal (via the heap) that concurrently was removed.
Own Id: OTP-16193
Fix bug causing VM crash due to memory corruption of distribution entry. Probability of crash increases if Erlang distribution is frequently disconnected and reestablished towards same node names. Bug exists since OTP-21.0.
Own Id: OTP-16224 Aux Id: ERL-1044
Fix bug where the receive marker used by the runtime to do the receive queue optimization could be incorrectly set. The symptom of this would be that a message that should match in a receive never matches.
The bug requires the OTP-22 compiler and multiple selective receives to trigger. See OTP-16219 for details about the bug fix in the compiler.
Own Id: OTP-16241 Aux Id: ERL-1076 OTP-16219
Fixed bug causing crash of VM built with configuration --enable--sharing-preserving. Provoked when a sent message contains both a bit string and the heap binary (< 65 bytes) which the bit string was matched from. Bug exists since OTP-19.0 but has seen to be easier to provoke since OTP-22.1.
Own Id: OTP-16265 Aux Id: ERL-1064

Erts 10.3.5.6

Fixed Bugs and Malfunctions

Fix a bug in binary_to_term that would crash the emulator if a term larger than 16GB was to be decoded.
Own Id: OTP-16058 Aux Id: PR-2382
When communicating with a simultaneously exiting port via the erlang:port_*() BIFs one could sometimes get stray {Ref, What} messages. Where Ref was a reference and What usually were the atom badarg.
Own Id: OTP-16107 Aux Id: ERL-1049

Erts 10.3.5.5

Fixed Bugs and Malfunctions

process_info(P,binary) would neglect to look through heap fragments, potentially missing a few binaries associated with the process.
Own Id: OTP-15978 Aux Id: ERIERL-366
Fixed bug triggered if a process is killed during call to persistent_term:put or persistent_term:erase.
Own Id: OTP-16041

Improvements and New Features

Fixed rare emulator crash in instrument:allocations/0-1.
Own Id: OTP-15983

Erts 10.3.5.4

Fixed Bugs and Malfunctions

Fixed bug causing VM crash when doing textual dump of a process containing an unhandled monitor down signal. Textual process dumps can be done with erlang:system_info(procs), trace feature process_dump, Erlang shell break menu and a crashdump. Bug exist since OTP 21.0.
Own Id: OTP-15909 Aux Id: ERL-979
lists:subtract/2 would produce incorrect results for some inputs on 64-bit platforms.
Own Id: OTP-15938 Aux Id: ERL-986
Fixed a bug in the loader that was similar to OTP-15938, yielding incorrect code for some inputs on 64-bit platforms.
Own Id: OTP-15939
Fixed bug causing scheduler threads in rare cases to block spinnning indefinitely. Bug exists since OTP 21.0.
Own Id: OTP-15941 Aux Id: PR-2313

Erts 10.3.5.3

Fixed Bugs and Malfunctions

If you set {linger,{true,0}} on a gen_tcp listen socket, accept a connection on that socket, and then close the accepted socket, now the linger zero setting is transferred to the accepted socket. Before this correction that information was lost and the close behaviour on the accepted socket incorrect.
Own Id: OTP-15370 Aux Id: ERIERL-353
Fixed process_info(Pid,reductions) to not categorically increase reduction count of the measured process Pid. Repeated reduction measure of an idle process will most often (but not guaranteed) return the same value, like it behaved before OTP 21.3.8.
Own Id: OTP-15865 Aux Id: ERL-964
The runtime system disconnected a connection if it received an exit/2 signal where the recipient was a process on an old incarnation of the current node. That is, the receiving node had the same node name, but another "creation" number. The signal will now just be dropped since the receiving process no longer exists.
Own Id: OTP-15867 Aux Id: ERIERL-373

Improvements and New Features

The possibility to send ancillary data, in particular the TOS field, has been added to gen_udp:send/4,5.
Own Id: OTP-15747 Aux Id: ERIERL-294

Erts 10.3.5.2

Fixed Bugs and Malfunctions

In nested use of try/catch, rethrowing an exception using erlang:raise/3 with a different class would not always be able to change the class of the exception.
Own Id: OTP-15834 Aux Id: ERIERL-367
Fixed bug in seq_trace:set_token(label,Term) which could cause VM crash if Term was heap allocated (not an atom, small integer, local pid or port). Bug exists since OTP 21.0 when terms other than small integers were first allowed as labels.
Own Id: OTP-15849 Aux Id: ERL-700
Fix seq_trace:print/2 not to raise badarg exception if label is not a small integer. Bug exists since OTP 21.0.
Own Id: OTP-15859 Aux Id: ERL-700

Erts 10.3.5.1

Fixed Bugs and Malfunctions

Fixed a buffer overflow when binary_to_existing_atom/2 and list_to_existing_atom/2 was used with the latin1 encoding.
Own Id: OTP-15819 Aux Id: ERL-944

Erts 10.3.5

Fixed Bugs and Malfunctions

Fixed more bugs in process_info(reductions) causing it to sometimes behave non-monotonic. That is, a subsequent call toward the same process could return a lower reduction value.
Own Id: OTP-15793 Aux Id: ERIERL-337, OTP-15709

Erts 10.3.4

Fixed Bugs and Malfunctions

Add missing documentation of new external tags NEW_PID, NEW_PORT and NEWER_REFERENCE introduced in OTP 19.
These new tags are planned to be "activated" in OTP 23 when distribution capability flag DFLAG_BIG_CREATION becomes mandatory. Older nodes (>= 19) are able to decode these new tags and send them back to the new node. Nodes older than OTP 23 will however never encode their own local pids, ports and references using the new tags.
Own Id: OTP-15766

Erts 10.3.3

Fixed Bugs and Malfunctions

Fix erlang:open_port/2 with the fd option to correctly cleanup the pollset when the port is closed. Before this fix there would be error printouts sent to logger when the same fd was reused in a new port.
Own Id: OTP-15753 Aux Id: ERL-900

Erts 10.3.2

Fixed Bugs and Malfunctions

Fixed a bug in seq_trace:reset_trace/0 that could crash the emulator.
Own Id: OTP-15704
Fixed bug in process_info(reductions) causing it to sometimes return invalid results.
Own Id: OTP-15709 Aux Id: ERIERL-337

Erts 10.3.1

Fixed Bugs and Malfunctions

If a suspend/resume signal pair was sent to a process while it was executing dirty, the receiving process could later end up in a suspended state indefinitely. This bug was introduced in ERTS version 10.0 (OTP 21.0).
Suspend/resume signals are sent from erlang:suspend_process()/erlang:resume_process(). The dbg trace tool utilize this functionality and could thus trigger this bug.
Own Id: OTP-15688
Fix a possible deadlock when terminating the ERTS caused by a dirty scheduler not releasing it's run-queue lock when terminating.
Own Id: OTP-15690 Aux Id: PR-2172

Erts 10.3

Fixed Bugs and Malfunctions

When multiplying a number by itself, a word beyond the number on the heap could be read (and ignored). This bug was extremely unlikely to actually cause a real problem.
Own Id: OTP-15484
Fix bug where doing seq_trace:reset_trace() while another process was doing a garbage collection could cause the run-time system to segfault.
Own Id: OTP-15490
Fix reading of ancillary data from packet oriented sockets on old Linux kernel versions. Without this fix, getting the data would cause the port to enter an infinite loop.
Own Id: OTP-15494
Fix bug where crash dumping or doing erlang:system_info(procs) while another process was doing a garbage collection could cause the run-time system to segfault.
Own Id: OTP-15527
Fix erlang:system_info(kernel_poll) to return correct value. Before this fix, the call always returned false.
Own Id: OTP-15556
Fix bug in enif_make_map_from_arrays that would produce broken maps when number of keys were 32. Bug exists since OTP 21.0.
Own Id: OTP-15567
Fix a bug in binary:encode_unsigned that may cause a read of uninitialized memory.
The bug existed since the function was added (OTP R16B02).
Own Id: OTP-15583 Aux Id: PR-2118
Fixed a bug that could cause heart to kill an exiting node before it had time to flush all buffered writes. If environment variable HEART_KILL_SIGNAL=SIGABRT was set a superfluous core dump could also be generated.
Own Id: OTP-15599 Aux Id: ERIERL-298
Fix enif_consume_timeslice to be a no-op on dirty scheduler and not crash debug compiled emulator.
Own Id: OTP-15604
Fixed macro redefinition warnings.
Own Id: OTP-15629
to_erl fixed to not garble terminal input beyond 7-bit ASCII.
Own Id: OTP-15650 Aux Id: ERL-854, PR-2161
Minor fixes for make clean.
Own Id: OTP-15657
Fixed a bug in all ets:select* and ets:match* functions that could in some rare cases lead to very poor performance.
Own Id: OTP-15660 Aux Id: ERL-869

Improvements and New Features

Add erlang:system_flag(system_logger, Pid) and erlang:system_info(system_logger). This system_flag can be used to set the process that will receive the logging messages generated by ERTS.
Own Id: OTP-15375
integer_to_list/2 and integer_to_binary/2 are now implemented in C, improving their performance.
Own Id: OTP-15503 Aux Id: PR-2052
Improved term_to_binary to do more fair reduction count and yielding when encoding large byte lists (strings).
Own Id: OTP-15514 Aux Id: ERL-774
Made internal port drivers more robust against erlang:port_control with invalid arguments and added documentation warnings about such abuse.
Own Id: OTP-15555 Aux Id: ERIERL-231
Fix bug on NetBSD where the exit_status from a port program would never be sent.
Own Id: OTP-15558 Aux Id: ERL-725
There is a new function persistent:term(Key, Default) to allow specifying a default when looking up a persistent term.
Own Id: OTP-15576 Aux Id: ERL-843
A transitory emulator option '+ztma true' has been added to allow running existing BEAM code that relies on "tuple calls" (dispatch on parameterized modules) which has been compiled under OTP 20 or earlier. This option will be removed in OTP 22, so such modules should eventually be recompiled with the +tuple_calls option.
Own Id: OTP-15580 Aux Id: PR-2113

Erts 10.2.5

Fixed Bugs and Malfunctions

Fixes of install/release phase in build system.
- The source tree was modified when installing/releasing and/or applying a patch.
- Some files were installed with wrong access rights.
- If applying a patch (using otp_patch_apply) as another user (except root) than the user that built the source, the documentation was not properly updated.
Own Id: OTP-15551
Setting the recbuf size of an inet socket the buffer is also automatically increased. Fix a bug where the auto adjustment of inet buffer size would be triggered even if an explicit inet buffer size had already been set.
Own Id: OTP-15651 Aux Id: ERIERL-304
Reading from UDP using active true or active N mode has been optimized when more packets than specified by read_packets are available on the socket.
Own Id: OTP-15652 Aux Id: ERIERL-304

Erts 10.2.4

Fixed Bugs and Malfunctions

When using the {linger,{true,T}} option; gen_tcp:listen/2 used the full linger time before returning for example eaddrinuse. This bug has now been corrected.
Own Id: OTP-14728 Aux Id: ERIERL-303

Erts 10.2.3

Fixed Bugs and Malfunctions

Fix bug where doing a gen_tcp:send on a socket with delay_send set to true could cause a segfault if the other side closes the connection.
Bug was introduced in erts-10.2 (OTP-21.2).
Own Id: OTP-15536 Aux Id: ERL-827
Fix a race condition when a port program closes that could result in the next started port to hang during startup.
When this fault happens the following error is normally (but not always) logged:
=ERROR REPORT==== 14-Jan-2019::10:45:52.868246 ===
Bad input fd in erts_poll()! fd=11, port=#Port<0.505>, driver=spawn, name=/bin/sh -s unix:cmd
Bug was introduced in erts-10.0 (OTP-21.0).
Own Id: OTP-15537
Fix a bug where polling for external events could be delayed for a very long time if all active schedulers were 100% loaded.
Bug was introduced in erts-10.2 (OTP-21.2).
Own Id: OTP-15538 Aux Id: ERIERL-229

Erts 10.2.2

Fixed Bugs and Malfunctions

Fixed a crash when dangling files were closed after init:restart/0.
Own Id: OTP-15495 Aux Id: ERL-821
A bug that could cause dirty schedulers to become unresponsive has been fixed.
Own Id: OTP-15509 Aux Id: PR-2027, PR-2093

Erts 10.2.1

Fixed Bugs and Malfunctions

Fixed bug on big endian architectures when changing file permissions or ownership with file:change_mode, change_owner, change_group or write_file_info. Bug exists since OTP-21.0.
Own Id: OTP-15485
Fixed bug in atomics with option {signed,false} when returned values are (1 bsl 63) or larger. Could cause heap corruption leading to VM crash or other unpleasant symptoms. Bug exists since OTP-21.2 when module atomics was introduced.
Own Id: OTP-15486 Aux Id: PR-2061
Fixed bug in operator band of two negative operands causing erroneous result if the absolute value of one of the operands have the lowest N*W bits as zero and the other absolute value is not larger than N*W bits. N is an integer of 1 or larger and W is 32 or 64 depending on word size.
Own Id: OTP-15487 Aux Id: ERL-804

Erts 10.2

Fixed Bugs and Malfunctions

When a process was waiting for a TCP socket send operation to complete, and another process closed the socket during that send, the sending process could hang. This bug has now been corrected.
Own Id: OTP-12242 Aux Id: ERL-561
Document bit_size in match specifications and allow it in ets:fun2ms.
Own Id: OTP-15343 Aux Id: PR-1962
Fixed bug in ets:select_replace when called with a fully bound key could cause a following call to ets:next or ets:prev to crash the emulator or return invalid result.
Own Id: OTP-15346
When a module has been purged from memory, any literals belonging to that module will be copied to all processes that hold references to them. The max heap size limit would be ignored in the garbage collection initiated when copying literals to a process. If the max heap size was exceeded, the process would typically be terminated in the following garbage collection. Corrected to terminate the process directly if copying a literal would exceed the max heap size.
Own Id: OTP-15360
Fix compilation of run_erl on Solaris 11.4 and later.
Own Id: OTP-15389
Fixed a bug where lists:reverse/1-2 could use far too many reductions. This bug was introduced in OTP 21.1.
Own Id: OTP-15436
Fixed a bug where a dirty scheduler could stay awake forever if a distribution entry was removed as part of a dirty GC.
Own Id: OTP-15446 Aux Id: PR-2024
Fix microstate accounting handing in various places. Most importantly the GC states when the GC is run on a dirty scheduler are now managed correctly.
Own Id: OTP-15450 Aux Id: ERIERL-229
Fixed bug in file:sendfile when the send operation failed. For sockets in active modes it could cause emulator crash or a hanging call. For sockets with {active,false} an unexpected {inet_reply, _, _} message could be sent to the calling process. The bug exists since OTP-21.0.
Own Id: OTP-15461 Aux Id: ERL-784
The erts configure script has been updated to reject any CFLAGS that does not have -O. This in order to prevent the common mistake of forgetting to add -O2 to custom CFLAGS.
Own Id: OTP-15465
Fix reduction count in lists:member/2
Own Id: OTP-15474 Aux Id: ERIERL-229

Improvements and New Features

New counters and atomics modules supplies access to highly efficient operations on mutable fixed word sized variables.
Own Id: OTP-13468
There is a new module persistent_term that implements a term storage suitable for terms that are frequently used but never or infrequently updated. Lookups are done in constant time without copying the terms.
Own Id: OTP-14669 Aux Id: PR-1989
A function inet:getifaddrs/1 that takes a list with a namespace option has been added, for platforms that support that feature, for example Linux (only?).
Own Id: OTP-15121 Aux Id: ERIERL-189, PR-1974
Added the nopush option for TCP sockets, which corresponds to TCP_NOPUSH on *BSD and TCP_CORK on Linux.
This is also used internally in file:sendfile to reduce latency on subsequent send operations.
Own Id: OTP-15357 Aux Id: ERL-698
List subtraction (The -- operator) will now yield properly on large inputs.
Own Id: OTP-15371
Optimize handling of send_delay for tcp sockes to better work with the new pollthread implementation introduced in OTP-21.
Own Id: OTP-15471 Aux Id: ERIERL-229
Optimize driver_set_timer with a zero timeout to short-circuit and not create any timer structure, but instead schedule the timer immediately.
Own Id: OTP-15472 Aux Id: ERIERL-229
Add erl_xcomp_code_model_small as a cross configure variable in order to let the emulator be build with the assumption that a small code model will be used on the target machine.
Own Id: OTP-15473 Aux Id: ERIERL-229
Add a new pollset that is made to handle sockets that use {active, true} or {active, N}. The new pollset will not be polled by a pollthread, but instead polled by a normal scheduler.
This change was made because of the overhead associated with constantly having to re-apply the ONESHOT mechanism on fds that all input events were interesting.
The new pollset is only active on platforms that support concurrent kernel poll updates, i.e. Linux and BSD.
Own Id: OTP-15475 Aux Id: ERIERL-229
Fix bug where emulator would segfault if a literal message was sent when sequence tracing was enabled.
Own Id: OTP-15478 Aux Id: ERL-741

Erts 10.1.3

Improvements and New Features

Added an optional ./configure flag to compile the emulator with spectre mitigation: --with-spectre-mitigation
Note that this requires a recent version of GCC with support for spectre mitigation and the --mindirect-branch=thunk flag, such as 8.1.
Own Id: OTP-15430 Aux Id: ERIERL-237

Erts 10.1.2

Fixed Bugs and Malfunctions

Fixed a rare bug where files could be closed on a normal instead of an IO scheduler, resulting in system instability if the operation blocked.
Own Id: OTP-15421

Erts 10.1.1

Fixed Bugs and Malfunctions

A bug where the socket option 'pktoptions' caused a read of uninitialized memory has been fixed. Would cause malfunction on FreeBSD.
Own Id: OTP-14297 Aux Id: OTP-15141
Fixed a memory leak on errors when reading files.
Own Id: OTP-15318
File access through UNC paths works again on Windows. This regression was introduced in OTP 21.
Own Id: OTP-15333 Aux Id: ERL-737

Erts 10.1

Fixed Bugs and Malfunctions

Fix the seq_trace token to not be cleared when a process receives messages sent by erts. Some examples of when this could happen is all port BIFs, i.e. open_port, port_command etc etc.
Fix so that messages sent by nifs can be traced using normal and seq_trace tracing.
Own Id: OTP-15038 Aux Id: ERL-602
Fixed specs and documentation for process_info item monitored_by to include port identifiers and nif resources as possible types.
Own Id: OTP-15180 Aux Id: ERL-648
Fix bug in generation of erl_crash.dump, which could cause VM to crash.
Bug exist since erts-9.2 (OTP-20.2).
Own Id: OTP-15181
Fix bug where ctrl-break or ctrl-c would not trigger the break mode properly on Windows. This bug was introduced in erts-10.0 (OTP-21).
Own Id: OTP-15205
Fix a performance bug for reception of UDP packages, where a memory buffer would be reallocated when it should not have been.
Introduce a limit on the maximum automatic increase of the UDP user-space buffer to the theoretical max of the network PATH, i.e. 65535.
Own Id: OTP-15206
Fix alignment of erts allocator state internally in erts. With the improper alignment the emulator would refuse to start when compiled with clang on 32-bit systems.
Own Id: OTP-15208 Aux Id: PR-1897 ERL-677
Fix bug where too many concurrent calls to erlang:open_port({spawn,"cmd"},...) would result in the emulator terminating with the reason "Failed to write to erl_child_setup: ". After this fix the open_port call will throw an emfile exception instead.
Own Id: OTP-15210
Upgraded the ERTS internal PCRE library from version 8.41 to version 8.42. See http://pcre.org/original/changelog.txt for information about changes made to PCRE. This library implements major parts of the re regular expressions module.
Own Id: OTP-15217
Fix open_port({fd,X,Y}, ...) to release the file descriptors from the pollset when closing the port. Without this fix the same file descriptor number could not be reused when doing multiple open_port and port_close sequences.
Own Id: OTP-15236 Aux Id: ERL-692
Fixed bug in float_to_list/2 and float_to_binary/2 with options [{decimals,0},compact] causing totally wrong results. Bug exists since OTP-21.0.
Own Id: OTP-15276 Aux Id: PR-1920
Fixed bug in erlang:memory causing ets to report too much. This small false memory leak (16 bytes each time) can only happen when a specific race condition occurs between scheduler threads on a table with option write_concurrency.
Own Id: OTP-15278
Minor configure test fixes
Own Id: OTP-15282
Improved robustness of distribution connection setup. In OTP-21.0 a truly asynchronous connection setup was introduced. This is further improvement on that work to make the emulator more robust and also be able to recover in cases when involved Erlang processes misbehave.
Own Id: OTP-15297 Aux Id: OTP-15279, OTP-15280

Improvements and New Features

The socket options recvtos, recvttl, recvtclass and pktoptions have been implemented in the socket modules. See the documentation for the gen_tcp, gen_udp and inet modules. Note that support for these in the runtime system is platform dependent. Especially for pktoptions which is very Linux specific and obsoleted by the RFCs that defined it.
Own Id: OTP-15145 Aux Id: ERIERL-187

Erts 10.0.8

Fixed Bugs and Malfunctions

As of ERTS version 10.0 (OTP 21.0) the erl_child_setup program, which creates port programs, ignores TERM signals. This setting was unintentionally inherited by port programs. Handling of TERM signals in port programs has now been restored to the default behavior. That is, terminate the process.
Own Id: OTP-15289 Aux Id: ERIERL-235, OTP-14943, ERL-576
The fix made for OTP-15279 in erts-10.07 (OTP-21.0.8) was not complete. It could cause a new connection attempt to be incorrectly aborted in certain cases. This fix will amend that flaw.
Own Id: OTP-15296 Aux Id: OTP-15279, ERIERL-226

Erts 10.0.7

Fixed Bugs and Malfunctions

A process could get stuck in an infinite rescheduling loop between normal and dirty schedulers. This bug was introduced in ERTS version 10.0.
Thanks to Maxim Fedorov for finding and fixing this issue.
Own Id: OTP-15275 Aux Id: PR-1943
Garbage collection of a distribution entry could cause an emulator crash if net_kernel had not brought previous connection attempts on it down properly.
Own Id: OTP-15279 Aux Id: ERIERL-226

Erts 10.0.6

Fixed Bugs and Malfunctions

A race between termination of a process and resume of the same process via erlang:resume_process/1 could cause the VM to crash. This bug was introduced in erts version 10.0 (OTP 21.0).
Own Id: OTP-15237
When tracing on running, in trace events could be lost when a process was rescheduled between a dirty and a normal scheduler.
Own Id: OTP-15269 Aux Id: ERL-713

Erts 10.0.5

Fixed Bugs and Malfunctions

Fixed a bug which caused an emulator crash when enif_send() was called by a NIF that executed on a dirty scheduler. The bug was either triggered when the NIF called enif_send() without a message environment, or when the process executing the NIF was send traced.
Own Id: OTP-15223
Fixed a bug causing some Erlang references to be inconsistently ordered. This could for example cause failure to look up certain elements with references as keys in search data structures. This bug was introduced in R13B02.
Thanks to Simon Cornish for finding the bug and supplying a fix.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-15225

Erts 10.0.4

Fixed Bugs and Malfunctions

Fixed a bug that prevented the noshell option from working correctly on Mac OS X and BSD.
Own Id: OTP-15169
Fixed a crash when matching directly against a literal map using a single key that had been saved on the stack.
Own Id: OTP-15184
Fix node crash when passing a bad time option to file:read_file_info/2.
Own Id: OTP-15196

Erts 10.0.3

Fixed Bugs and Malfunctions

Fixed a scheduler bug that caused normal schedulers to run dirty code.
Own Id: OTP-15154
Fixed a bug in erlang:trace_info/2 which caused the emulator to crash when a bad argument was passed. The bug was introduced in ERTS version 10.0.
Own Id: OTP-15183 Aux Id: ERL-670

Erts 10.0.2

Fixed Bugs and Malfunctions

Fixed a rare bug that could cause processes to be scheduled after they had been freed.
Own Id: OTP-15067 Aux Id: ERL-573
Fixed a race condition in the inet driver that could cause receive to hang when the emulator was compiled with gcc 8.
Own Id: OTP-15158 Aux Id: ERL-654

Erts 10.0.1

Fixed Bugs and Malfunctions

The keys used in os:getenv and os:putenv are case-insensitive again on Windows.
Own Id: OTP-15147 Aux Id: ERL-644

Erts 10.0

Fixed Bugs and Malfunctions

The type specifications for file:posix/0 and inet:posix/0 have been updated according to which errors file and socket operations should be able to return.
Own Id: OTP-14019 Aux Id: ERL-550
Fix error printout from run_erl and a bug that could cause unintended fds to be leaked into the started program.
Own Id: OTP-14537 Aux Id: PR1529
File operations used to accept filenames containing null characters (integer value zero). This caused the name to be truncated and in some cases arguments to primitive operations to be mixed up. Filenames containing null characters inside the filename are now rejected and will cause primitive file operations to fail.
Also environment variable operations used to accept names and values of environment variables containing null characters (integer value zero). This caused operations to silently produce erroneous results. Environment variable names and values containing null characters inside the name or value are now rejected and will cause environment variable operations to fail.
Primitive environment variable operations also used to accept the $= character in environment variable names causing various problems. $= characters in environment variable names are now also rejected.
Also os:cmd/1 now reject null characters inside its command.
erlang:open_port/2 will also reject null characters inside the port name from now on.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-14543 Aux Id: ERL-370
Fix bugs related to the bookkeeping of microstate accounting states.
Own Id: OTP-14652
os:putenv and os:getenv no longer access the process environment directly and instead work on a thread-safe emulation. The only observable difference is that it's not kept in sync with libc getenv(3) / putenv(3), so those who relied on that behavior in drivers or NIFs will need to add manual synchronization.
On Windows this means that you can no longer resolve DLL dependencies by modifying the PATH just before loading the driver/NIF. To make this less of a problem, the emulator now adds the target DLL's folder to the DLL search path.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-14666
Corrected erlang:is_builtin(erlang, M, F) to return true for apply/2 and yield/0.
Own Id: OTP-14713 Aux Id: ERL-500
Fixed a bug where the PATH environment variable wasn't updated correctly on a release downgrade, effectively keeping the PATH of the new release.
Own Id: OTP-14719
A receive optimization that avoids scanning the entire message queue when receiving a message containing a freshly created reference could in rare circumstances (involving recursive calls to the functions that does the receive) cause the receive to hang. This has been corrected.
Own Id: OTP-14782 Aux Id: ERL-511
Fix building of Erlang/OTP on platforms which have small data area with short addressing. For example the PowerPC/RTEMS platform.
Own Id: OTP-14909 Aux Id: PR-1692
Fixed a crash when enif_make_binary is called with a binary produced by enif_inspect_binary in a different environment.
Own Id: OTP-14931
Fixed a crash when enif_make_binary is called more than once with a binary that had previously been added to an enif_ioq.
Own Id: OTP-14932
The erl_child_setup program now ignores SIGTERM signals.
Own Id: OTP-14943 Aux Id: ERL-576
Force 64-bit alignment on pre-allocators on architectures which needs it.
Own Id: OTP-14977
Fixed a bug where dirty scheduler picked up non-dirty work.
Own Id: OTP-14978
Calls to gen_tcp:send/2 on closed sockets now returns {error, closed} instead of {error,enotconn}.
Own Id: OTP-15001
erlang:monotonic_time/1 failed with badarg when passing the perf_counter time unit as argument.
Own Id: OTP-15008
Fix bug where rapid init:restart() calls would sometimes crash because a code load request leaked in between the restarts.
Own Id: OTP-15013
Improve float_to_list(F, [{decimals,D}]) to closer conform with io_lib:format("~.*f", [D,F]).
There are however, still cases when float_to_list does not produce the exact same result as io_lib:format, especially for large values F and/or many decimals D.
Own Id: OTP-15015 Aux Id: OTP-14890
Fixed a deadlock that would occur on certain allocators when a reallocation failed with +ramv enabled.
Own Id: OTP-15024
Fix bug that made it impossible to use an erl_tracer as the seq_trace trace receiver.
Own Id: OTP-15029
Fix bug where a large (> 1 GB) emulator generated error logger message would cause the emulator to crash.
Own Id: OTP-15032
The emulator will no longer crash when reading the file information of an ordinary file that has an NTFS reparse point, such as files stored in a OneDrive-mapped folder.
Own Id: OTP-15062 Aux Id: ERL-615
Fixed bug in enif_binary_to_term which could cause memory corruption for immediate terms (atoms, small integers, pids, ports, empty lists).
Own Id: OTP-15080
Fixed bug in erlang:system_profile/2 that could cause superfluous {profile,_,active,_,_} messages for terminating processes.
Own Id: OTP-15085
On OSs with per thread CPU time support, change cpu_timestamp in erlang:trace/3 to use it instead of per process CPU time. This makes this option usable on such OSs when running multiple schedulers.
Own Id: OTP-15090
Fix segfault in abort_signal_task which could happen if a port terminated while there were outstanding port tasks that were not signals, for example a ready_input/ready_output event.
Own Id: OTP-15108 Aux Id: ERL-621
Fixed bug in ets that could cause VM crash if process A terminates after fixating a table and process B deletes the table at "the same time". The table fixation could be done with ets:safe_fixtable or if process A terminates in the middle of a long running select or match call.
Own Id: OTP-15109
Owner and group changes through file:write_file_info, file:change_owner, and file:change_group will no longer report success on permission errors.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-15118
Fix a bug error reporting from escripts on windows where the error message would get garbled.
Own Id: OTP-15119 Aux Id: PR-1826
Fix segfault when a process is internally re-scheduled while being traced for in out events. This bug was introduced in erts-8.0 (OTP-19.0).
Own Id: OTP-15125

Improvements and New Features

It is now possible to open device files and FIFOs with file:open/2.
Own Id: OTP-11462
The erlang:system_flag(scheduler_wall_time,Bool) call is now reference counted and will be turned off if the (last) process that started the performance statistics dies. Thus it is no longer possible to start the statistics with rpc:call(Node, erlang, system_flag, [scheduler_wall_time, true]) since it will be turned off directly afterwards when the rpc process dies.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-11694
A new logging API is added to Erlang/OTP, see the logger manual page, and section Logging in the Kernel User's Guide.
Calls to error_logger are automatically redirected to the new API, and legacy error logger event handlers can still be used. It is, however, recommended to use the Logger API directly when writing new code.
Notice the following potential incompatibilities:
- Kernel configuration parameters error_logger still works, but is overruled if the default handler's output destination is configured with Kernel configuration parameter logger.
  In general, parameters for configuring error logger are overwritten by new parameters for configuring Logger.
- The concept of SASL error logging is deprecated, meaning that by default the SASL application does not affect which log events are logged.
  By default, supervisor reports and crash reports are logged by the default Logger handler started by Kernel, and end up at the same destination (terminal or file) as other standard log event from Erlang/OTP.
  Progress reports are not logged by default, but can be enabled by setting the primary log level to info, for example with the Kernel configuration parameter logger_level.
  To obtain backwards compatibility with the SASL error logging functionality from earlier releases, set Kernel configuration parameter logger_sasl_compatible to true. This prevents the default Logger handler from logging any supervisor-, crash-, or progress reports. Instead, SASL adds a separate Logger handler during application start, which takes care of these log events. The SASL configuration parameters sasl_error_logger and sasl_errlog_type specify the destination (terminal or file) and severity level to log for these events.
Since Logger is new in Erlang/OTP 21.0, we do reserve the right to introduce changes to the Logger API and functionality in patches following this release. These changes might or might not be backwards compatible with the initial version.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-13295
gen_sctp:connect_init/4 or rather connect in inet_drv.c for SCTP has been fixed to not check the write file descriptor for writeability after a connect, since for SCTP (SOCK_SEQPACKET) that property does not seem to be any kind of indicator for when a connect has finished. This fixes connects that the OS returned as "in progress" that was misinterpreted by gen_sctp:connect_init as failed.
Own Id: OTP-13760 Aux Id: PR-1592
The file driver has been rewritten as a NIF, decreasing the latency of file operations. Notable incompatibilities are:
- The use_threads option for file:sendfile/5 no longer has any effect; we either use non-blocking sendfile(2) or fall back to file:read + gen_tcp:send.
- The file-specific DTrace probes have been removed. The same effect can be achieved with normal tracing together with the nif__entry/nif__return probes to track scheduling.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-14256
The I/O polling functionality of erts has been re-written to better make use of the OSs polling mechanisms. This change means that erts will now always prefer to use a kernel-polling mechanism if possible. Also all of the I/O polling has been moved to dedicated threads instead of being placed in the scheduler loops.
As a result of this, the erl options +K and +secio have been removed. It is still possible to disable kernel-poll, but it has to be done at compile time through the configure option --disable-kernel-poll.
The new erl options +IOt and +IOp can be used to change how many IO poll threads and poll sets that erts should use. See their respective documentation for more details.
Own Id: OTP-14346
Truly asynchronous auto-connect. Earlier, when erlang:send was aimed toward an unconnected node, the function would not return until the connection setup had completed (or failed). Now the function returns directly after the message has been enqueued and the connection setup started.
The same applies to all distributed operations that may trigger auto-connect, i.e. '!', send, link, monitor, monitor_node, exit/2 and group_leader.
The interface for all these functions are unchanged as they do not return connection failures. The only exception is erlang:monitor where a possible incompatibility is introduced: An attempt to monitor a process on a primitive node (such as erl_interface or jinterface), where remote process monitoring is not implemented, will no longer fail with badarg exception. Instead a monitor will be created, but it will only supervise the connection to the node.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-14370
Changed the default behaviour of .erlang loading: .erlang is no longer loaded from the current directory. c:erlangrc(PathList) can be used to search and load an .erlang file from user specified directories.
escript, erlc, dialyzer and typer no longer load an .erlang at all.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-14439
New functionality for implementation of alternative carriers for the Erlang distribution has been introduced. This mainly consists of support for usage of distribution controller processes (previously only ports could be used as distribution controllers). For more information see ERTS User's Guide ➜ How to implement an Alternative Carrier for the Erlang Distribution ➜ Distribution Module.
Own Id: OTP-14459
Add support for the lcc compiler and in extension the Elbrus 2000 platform.
Own Id: OTP-14492
Support for "tuple calls" have been removed from the run-time system. Tuple calls was an undocumented and unsupported feature which allowed the module argument for an apply operation to be a tuple: Var = dict:new(), Var:size(). This "feature" frequently caused confusion, especially when such call failed. The stacktrace would point out functions that don't exist in the source code.
For legacy code that need to use parameterized modules or tuple calls for some other reason, there is a new compiler option called tuple_calls. When this option is given, the compiler will generate extra code that emulates the old behavior for calls where the module is a variable.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-14497
Creation of small maps with literal keys has been optimized to be faster and potentially use less memory. The keys are combined into a literal key tuple which is put into the literal pool. The key tuple can be shared between many instances of maps having the same keys.
Own Id: OTP-14502
When an exception is thrown, include the arguments of the call in the stacktrace for BIFs band, bor, bsl, bsr, bxor, div, rem and the operators +, -, * and /.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-14508
The non-smp emulators have been removed. This means that the configure options --disable-threads and --enable-plain-emulator have been removed and configure will now refuse to build Erlang/OTP on platforms without thread support.
In order to achieve a similar setup as the non-smp emulator, it is possible to start Erlang/OTP with the +S 1 option.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-14518
Modules that use floating point constants compiled with R15 or earlier will need to be re-compiled before they can be loaded.
Own Id: OTP-14575
Implementation of true asynchronous signaling between processes in order to improve scalability. Signals affected include exit, monitor, demonitor, monitor triggered, link, unlink, and group leader.
Own Id: OTP-14589
Added a PGO (profile guided optimization) pass to the build step of erts. This can be disabled by passing --disable-pgo to configure.
Own Id: OTP-14604
Improved the performance of binary:split and binary:match.
Own Id: OTP-14610 Aux Id: PR-1480
It is not longer possible to disable dirty schedulers when building erlang.
Own Id: OTP-14613
Loaded BEAM code in a 64-bit system requires less memory because of better packing of operands for instructions.
These memory savings were achieved by major improvements to the beam_makeops scripts used when building the run time system and BEAM compiler. There is also new for documentation for beam_makeops that describes how new BEAM instructions and loader transformations can be implemented. The documentation is found in here in a source directory or git repository: erts/emulator/internal_doc/beam_makeops.md. An online version can be found here: https://github.com/erlang/otp/blob/master/erts/emulator/internal_doc/beam_makeops.md
Own Id: OTP-14626
file:read_file has been changed to read the content of files that report a size of 0 even when data can be read from them. An example of such a file is /proc/cpuinfo on Linux.
Own Id: OTP-14637 Aux Id: ERL-327 PR-1524
It is no longer possible to disable the temp_alloc allocator. Disabling it caused serious performance degradations and was never what was wanted.
Own Id: OTP-14651
The reduction cost of sending messages is now constant. It will no longer scale according to the length of the receiving process' message queue.
Own Id: OTP-14667
Improved loading of modules with -on_load directive, to no longer block all schedulers when the load operation is completed.
Own Id: OTP-14680
On platforms with real-time signals available, SIGRTMIN+1 is now used as the internal scheduler suspend signal instead of SIGUSR2.
Own Id: OTP-14682
When the value returned from a 'catch' expression is ignored, no stacktrace will be built if an exception is caught. That will save time and produce less garbage. There are also some minor optimizations of 'try/catch' both in the compiler and run-time system.
Own Id: OTP-14683
The guarantees and non-guarantees of erlang:get_stacktrace/0 are now documented.
Own Id: OTP-14687
There is a new syntax in 'try/catch' for retrieving the stacktrace without calling 'erlang:get_stacktrace/0'. See the reference manual for a description of the new syntax. The 'erlang:get_stacktrace/0' BIF is now deprecated.
Own Id: OTP-14692
New 'used' option for binary_to_term/2 that will also return number of bytes actually read from the binary. This enables easy access to any extra data in the binary located directly after the returned term.
Own Id: OTP-14780
Added more statistics for erlang:system_info({allocator,A}) in the mbcs_pool section.
Own Id: OTP-14795 Aux Id: ERL-88
Added enif_ioq_peek_head to retrieve Erlang terms from NIF IO queues without having to resort to copying.
Own Id: OTP-14797
There is a new option 'makedep_side_effect' for the compiler and -MMD for 'erlc' that generates dependencies and continues to compile as normal.
Own Id: OTP-14830
Added ets:whereis/1 for retrieving the table identifier of a named table.
Own Id: OTP-14884
seq_trace labels may now be any erlang term.
Own Id: OTP-14899
Optimized the common case of monitor followed by send to the same local process. The monitor signal is now delayed in order to be piggybacked with the sent message and thereby only get one lock operation on the message queue of the receiver. A delayed monitor signal is flushed if no send has been done at the latest when the process is scheduled out.
Own Id: OTP-14901
Make hipe compiled code work on x86_64 (amd64) with OS security feature PIE, where executable code can be loaded into a random location. Old behavior, if hipe was enabled, was to disable PIE build options for the VM.
Own Id: OTP-14903
The number of driver async threads will now default to 1 as the standard drivers do not use them anymore. Users that changed this value to tweak the file driver should replace +A with +SDio since it now uses dirty IO schedulers instead of async threads.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-14928
Optimize == and /= for binaries with different sizes to be constant in time instead of proportional to the size of their common prefix.
Own Id: OTP-14934 Aux Id: PR-1708
Refactorings making some internal process flags available for other usage.
Own Id: OTP-14948
Removed need for HiPE to allocate native executable memory in low 2GB address space on x86_64. Command line option +MXscs is thereby obsolete and ignored.
Own Id: OTP-14951
Added enif_make_map_from_arrays for creating a populated map, analogous to enif_make_list_from_array.
Own Id: OTP-14954
Added configuration switches for busy-wait and wake up thresholds for dirty schedulers, and changing these settings for normal schedulers will no longer affect dirty schedulers.
Refer to the documentation for details. The new switches are +sbwtdcpu, +sbwtdio, +swtdcpu, and +swtdio.
The default busy wait threshold for dirty scheduler threads has also been lowered to short.
Own Id: OTP-14959
The list of "taints" now also includes dynamic loaded drivers in addition to NIF libraries. Statically linked drivers and NIF libraries that are part of erts are not included. The "taints" are returned by system_info(taints) and printed in the header of erl_crash.dump files.
Own Id: OTP-14960
Added instrument:allocations and instrument:carriers for retrieving information about memory utilization and fragmentation.
The old instrument interface has been removed, as have the related options +Mim and +Mis.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-14961
The process suspend functionality used by the erlang:suspend_process/2 BIF has been reimplemented using the newly introduced true asynchronous signaling between processes. This mainly to reduce memory usage in the process control block of all processes, but also in order to simplify the implementation.
Warning
You can easily create deadlocks if processes suspends each other (directly or in circles). In ERTS versions prior to ERTS version 10.0, the runtime system prevented such deadlocks, but this prevention has now been removed due to performance reasons.
Other ERTS internal functionality that used the previous process suspend functionality have also been reimplemented to use asynchronous signaling instead.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-14964 Aux Id: OTP-14589
Added the nifs option to ?MODULE:module_info/1 for listing a module's installed NIF functions.
Own Id: OTP-14965
New implementation of erlang:process_info/[1,2].
In the general case when inspecting another process, the new implementation sends an asynchronous process-info request signal to the other process and waits for the result instead of locking the other process and reading the result directly. In some special cases where no conflicts occur, signal order won't be violated, and the amount of data requested is guaranteed to be small, the inspected process may be inspected directly.
Appropriate amount of reductions are now also bumped when inspecting a process.
Own Id: OTP-14966
Removed process start time from crash dump in order to save memory in process control block.
Own Id: OTP-14975 Aux Id: PR-1597
Optimize erlang:put/2 when updating existing key with a new immediate value (atom, small integer, pid, port).
Own Id: OTP-14976
erlang:process_info/1 has been changed to no longer include messages by default. Instead erlang:process_info/2 should be used.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-14986 Aux Id: PR-1745
New erlang:system_info(ets_count) to get total number of ets tables existing at the local node.
Own Id: OTP-14987
New NIF functions: enif_mutex_name, enif_cond_name, enif_rwlock_name, enif_thread_name, enif_vfprintf, enif_vsnprintf.
Own Id: OTP-14994
When erlang:system_flag(backtrace_depth, 0) has been called, all exceptions will now contain the entry for one function (despite the zero). It used to be that a hand-made stack backtrace passed to erlang:raise/3 would be truncated to an empty list.
Own Id: OTP-15026
Fixed bug for named ets tables which could cause unexpected results from matchspec iteration functions (ets:select* and ets:match*) if the table was deleted and recreated with the same name during the iteration. The iteration could incorrectly continue through the recreated table. The expected correct behavior is now for the iteration call to fail with a badarg exception if the table is deleted before the iteration has completed.
Own Id: OTP-15031
Two new guards BIFs operating on maps have been added: map_get/2 and is_map_key/2. They do the same as maps:get/2 and maps:is_key/2, respectively, except that they are allowed to be used in guards.
Own Id: OTP-15037 Aux Id: PR-1784, PR-1802
Release run-queue lock while cleaning up terminated dirty process.
Own Id: OTP-15081
The callback module passed as -epmd_module to erl has been expanded to be able to do name and port resolving.
Documentation has also been added in the erl_epmd reference manual and ERTS User's Guide How to Implement an Alternative Node Discovery for Erlang Distribution.
Own Id: OTP-15086 Aux Id: PR-1694

Erts 9.3.3.15

Fixed Bugs and Malfunctions

A process could end up in a state where it got endlessly rescheduled without making any progress. This occurred when a system task, such as check of process code (part of a code purge), was scheduled on a high priority process trying to execute on a dirty scheduler.
Own Id: OTP-16436 Aux Id: ERL-1152
Fixed bug in erlang:list_to_ref/1 when called with a reference created by a remote note. Function list_to_ref/1 is intended for debugging and not to be used in application programs. Bug exist since OTP 20.0.
Own Id: OTP-16438
A process could get into an inconsistent state where it was runnable, but never scheduled for execution. This could occur when a mix of normal and low priority processes where scheduled on the same type of dirty scheduler simultaneously.
Own Id: OTP-16446 Aux Id: ERL-1157
Fixed erroneous mapping of exit reason from kill to killed on reception of some exit signals due to a broken link. This bug has existed since ERTS version 5.5.2 (OTP R11).
This bug was also unknowingly fixed in ERTS version 10.0 (OTP 21.0) due to a new ERTS internal implementation of signaling between processes.
Own Id: OTP-16465 Aux Id: ERL-1165, OTP-6160, OTP-14589
Corrected the valid range of the erl command line argument +SDio <NumberOfDirtyIoSchedulers> from 0..1024 to 1..1024. +SDio 0 was erroneously allowed which just caused the VM to crash on the first dirty I/O job scheduled.
Own Id: OTP-16481

Erts 9.3.3.14

Fixed Bugs and Malfunctions

A process calling erlang:system_flag(multi_scheduling, block) could end up blocked waiting for the operation to complete indefinitely.
Own Id: OTP-16379

Erts 9.3.3.13

Fixed Bugs and Malfunctions

A literal area could prematurely be released before all uses of it had been removed. This occurred either when a terminating process had a complex exit reason referring to a literal that concurrently was removed, or when a terminating process continued executing a dirty NIF accessing a literal (via the heap) that concurrently was removed.
Own Id: OTP-16193

Erts 9.3.3.12

Fixed Bugs and Malfunctions

The runtime system disconnected a connection if it received an exit/2 signal where the recipient was a process on an old incarnation of the current node. That is, the receiving node had the same node name, but another "creation" number. The signal will now just be dropped since the receiving process no longer exists.
Own Id: OTP-15867 Aux Id: ERIERL-373
Fix a bug in binary_to_term that would crash the emulator if a term larger than 16GB was to be decoded.
Own Id: OTP-16058 Aux Id: PR-2382
When communicating with a simultaneously exiting port via the erlang:port_*() BIFs one could sometimes get stray {Ref, What} messages. Where Ref was a reference and What usually were the atom badarg.
Own Id: OTP-16107 Aux Id: ERL-1049

Erts 9.3.3.11

Fixed Bugs and Malfunctions

Fixed a buffer overflow when binary_to_existing_atom/2 and list_to_existing_atom/2 was used with the latin1 encoding.
Own Id: OTP-15819 Aux Id: ERL-944

Erts 9.3.3.10

Fixed Bugs and Malfunctions

Fixes of install/release phase in build system.
- The source tree was modified when installing/releasing and/or applying a patch.
- Some files were installed with wrong access rights.
- If applying a patch (using otp_patch_apply) as another user (except root) than the user that built the source, the documentation was not properly updated.
Own Id: OTP-15551
Minor fixes for make clean.
Own Id: OTP-15657
Fixed a bug in all ets:select* and ets:match* functions that could in some rare cases lead to very poor performance.
Own Id: OTP-15660 Aux Id: ERL-869
Fix a possible deadlock when terminating the ERTS caused by a dirty scheduler not releasing it's run-queue lock when terminating.
Own Id: OTP-15690 Aux Id: PR-2172
Add missing documentation of new external tags NEW_PID, NEW_PORT and NEWER_REFERENCE introduced in OTP 19.
These new tags are planned to be "activated" in OTP 23 when distribution capability flag DFLAG_BIG_CREATION becomes mandatory. Older nodes (>= 19) are able to decode these new tags and send them back to the new node. Nodes older than OTP 23 will however never encode their own local pids, ports and references using the new tags.
Own Id: OTP-15766

Erts 9.3.3.9

Improvements and New Features

Added an optional ./configure flag to compile the emulator with spectre mitigation: --with-spectre-mitigation
Note that this requires a recent version of GCC with support for spectre mitigation and the --mindirect-branch=thunk flag, such as 8.1.
Own Id: OTP-15430 Aux Id: ERIERL-237

Erts 9.3.3.8

Fixed Bugs and Malfunctions

A bug that could cause dirty schedulers to become unresponsive has been fixed.
Own Id: OTP-15509 Aux Id: PR-2027, PR-2093

Erts 9.3.3.7

Fixed Bugs and Malfunctions

Fixed bug in operator band of two negative operands causing erroneous result if the absolute value of one of the operands have the lowest N*W bits as zero and the other absolute value is not larger than N*W bits. N is an integer of 1 or larger and W is 32 or 64 depending on word size.
Own Id: OTP-15487 Aux Id: ERL-804

Erts 9.3.3.6

Improvements and New Features

List subtraction (The -- operator) will now yield properly on large inputs.
Own Id: OTP-15371

Erts 9.3.3.5

Fixed Bugs and Malfunctions

ERTS internal trees of monitor structures could get into an inconsistent state. This could cause 'DOWN' messages not to be delivered when they should, as well as delivery of 'DOWN' messages that should not be delivered.
This bug was introduced in ERTS version 9.0 (OTP 20.0) and was fixed in ERTS version 10.0 (OTP 21.0) due to a rewrite of the monitor code. That is, this bug only exist in the OTP 20 release.
Own Id: OTP-15399 Aux Id: ERL-751, ERIERL-262, OTP-14205

Erts 9.3.3.4

Fixed Bugs and Malfunctions

Fixed bug in ets:select_replace when called with a fully bound key could cause a following call to ets:next or ets:prev to crash the emulator or return invalid result.
Own Id: OTP-15346

Erts 9.3.3.3

Fixed Bugs and Malfunctions

Fixed a bug which caused an emulator crash when enif_send() was called by a NIF that executed on a dirty scheduler. The bug was either triggered when the NIF called enif_send() without a message environment, or when the process executing the NIF was send traced.
Own Id: OTP-15223
Fixed a bug causing some Erlang references to be inconsistently ordered. This could for example cause failure to look up certain elements with references as keys in search data structures. This bug was introduced in R13B02.
Thanks to Simon Cornish for finding the bug and supplying a fix.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-15225

Erts 9.3.3.2

Fixed Bugs and Malfunctions

Fixed a race condition in the inet driver that could cause receive to hang when the emulator was compiled with gcc 8.
Own Id: OTP-15158 Aux Id: ERL-654
Fix bug in generation of erl_crash.dump, which could cause VM to crash.
Bug exist since erts-9.2 (OTP-20.2).
Own Id: OTP-15181

Erts 9.3.3.1

Fixed Bugs and Malfunctions

Fixed a rare bug that could cause processes to be scheduled after they had been freed.
Own Id: OTP-15067 Aux Id: ERL-573

Erts 9.3.3

Fixed Bugs and Malfunctions

Fixed bug in ets that could cause VM crash if process A terminates after fixating a table and process B deletes the table at "the same time". The table fixation could be done with ets:safe_fixtable or if process A terminates in the middle of a long running select or match call.
Own Id: OTP-15109

Erts 9.3.2

Fixed Bugs and Malfunctions

Fixed bug in enif_binary_to_term which could cause memory corruption for immediate terms (atoms, small integers, pids, ports, empty lists).
Own Id: OTP-15080
Fixed bug in erlang:system_profile/2 that could cause superfluous {profile,_,active,_,_} messages for terminating processes.
Own Id: OTP-15085

Erts 9.3.1

Fixed Bugs and Malfunctions

Fixed a crash in heart:get_cmd/0 when the stored command was too long.
Own Id: OTP-15034

Erts 9.3

Fixed Bugs and Malfunctions

Fixed a configure test for libz internals that unintentionally caused various native code in OTP to link against libz. Under certain circumstances this caused the build of OTP to fail.
Own Id: OTP-14840 Aux Id: ERL-529
File names containing unicode codepoints larger than 255 were not correctly encoded in stack traces.
Own Id: OTP-14847 Aux Id: ERL-544
Fix HiPE bug for binary constructs like <<X/utf8>> which could in rare cases cause faulty results or VM crash.
This fix affects both the hipe compiler and erts runtime in an incompatible way. Old hipe compiled files need to be recompiled to load and run properly as native.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-14850 Aux Id: PR-1664
Fix term_to_binary/2 spec for minor_version.
Own Id: OTP-14876 Aux Id: ERL-548
Fix bug in erlang:binary_to_integer/2 where invalid characters were not detected for bases larger then 10. e.g. binary_to_integer(<<":">>, 16) would return 3 and not badarg as it should.
Own Id: OTP-14879
Fixed bug in float_to_list/2 and float_to_binary/2 with option decimals that caused a faulty rounding up of the last decimal digit for about 6% of floats with a fraction part.
For example, float_to_list(0.145, [{decimals,1}]) returned "0.2" instead of "0.1".
Own Id: OTP-14890
Fix bug causing slow hipe execution in modules loaded early during boot or loaded by code:atomic_load or code:finish_loading.
Own Id: OTP-14891
Fixed a buffer overflow in an internal string formatting function that could be hit if specifying a long floating-point format specifier to erts_sprintf or similar.
Own Id: OTP-14920
erlang:iolist_to_iovec/1 and enif_inspect_iovec will no longer fail when provided with binaries that have been matched-out on a non-byte boundary.
Own Id: OTP-14921
iolist_to_binary/1 and erlang:iolist_to_iovec/1 will now badarg if supplied with a bitstring (without a list).
Own Id: OTP-14926
Reject loading modules with names containing directory separators ('/' or '\' on Windows).
Own Id: OTP-14933 Aux Id: ERL-564, PR-1716
Fix potential dead-lock when the tracer process dies while a the traced process is running on a dirty scheduler.
Own Id: OTP-14938

Improvements and New Features

More crash dump info such as: process binary virtual heap stats, full info for process causing out-of-mem during GC, more port related info, and dirty scheduler info.
Own Id: OTP-14820

Erts 9.2.1

Improvements and New Features

Improve search algorithm of abandoned memory carriers. Instead of limited linear search, each allocator instance maintain a balanced search tree of all its abandoned carriers for faster and more exhaustive search.
Own Id: OTP-14915 Aux Id: ERIERL-88
New erts_alloc command line options +M_acnl and +M_acfml to limit carrier abandonment.
Own Id: OTP-14916 Aux Id: ERIERL-88
New family of erts_alloc strategies: Age Order First Fit. Similar to "address order", but instead the oldest possible carrier is always chosen for allocation.
Own Id: OTP-14917 Aux Id: ERIERL-88
Add possibility to change allocator options at runtime with system_info(erts_alloc, ...). Only option sbct (single block carrier threshold) is currently supported via this interface.
Own Id: OTP-14918 Aux Id: ERIERL-88

Erts 9.2.0.1

Improvements and New Features

Extra internal consistency checks wrt communication with erl_child_setup process.
Own Id: OTP-15488 Aux Id: ERIERL-231

Erts 9.2

Fixed Bugs and Malfunctions

Fix a bug in tracing where the {caller} match spec function would be set to undefined incorrectly when used in conjunction with return_to or return_trace on some functions.
The functions effected are: erlang:put/2, erlang:erase/1, erlang:process_info/1,2, erlang:nif_load/2, erts_internal:garbage_collection/1 and erts_internal:check_process_code/1.
Because of this bug, the analysis done by fprof could become incorrect when the functions above are the tail-call in a function.
Own Id: OTP-14677
Fix emulator deadlock that would happen if trap_exit was set to true and a process sends an exit signal to itself using exit(self(), Reason) while receive tracing was enabled for that process.
Own Id: OTP-14678 Aux Id: ERL-495
Writing of crash dumps is significantly faster.
Maps are now included in crash dumps.
Constants terms would only be shown in one process, while other processes referencing the same constant term would show a marker for incomplete heap.
Own Id: OTP-14685 Aux Id: OTP-14611, OTP-14603, OTP-14595
The fallback home directory for windows has been changed to be the PROFILE directory instead of the WINDOWS directory. The fallback is used when the environment variables HOMEDRIVE and HOMEPATH have not been set.
Own Id: OTP-14691
Fix bug for hipe compiled code using <<X/utf32>> binary construction that could cause faulty result or even VM crash.
On architectures other than x86_64, code need to be recompiled to benefit from this fix.
Own Id: OTP-14740
Fixed bug in erlang:garbage_collect/2 and erlang:check_process_code/3, when called with option {async,ReqestId}. Could cause VM crash or heap corruption if RequestId was an immediate term (like a pid, atom or small integer). Bug exists since OTP-17.0.
Own Id: OTP-14752
ERLNIF_MINOR_VERSION wasn't bumped with the addition of `enif_ioq*`.
Own Id: OTP-14779
Purging of loaded code that contained "fake literals" (for example the magic reference obtained from 'ets:new/2') would crash the runtime system. Corrected.
Own Id: OTP-14791
Setting the size of the atom table to a number near 2147483647 (using the '+t' option) would cause the emulator to exit with a failure to allocate a huge amount of memory. This has been corrected. Also the usage message for the '+t' option has been corrected to show the correct upper limit 2147483647 instead of 0.
Own Id: OTP-14796
Fixed a bug that prevented registered process names from being resolved in lcnt results.
Own Id: OTP-14803
Formatting bugs were fixed in several HiPE debug BIFs.
Own Id: OTP-14804

Improvements and New Features

Binaries and some other data in crash dumps are now encoded in base64 (instead of in hex), which will reduce the size of crash dumps.
A few bugs in the handling of sub binaries in crashdump_viewer have been fixed.
Own Id: OTP-14686
Micro optimization for send operations of messages to other nodes. The local ack-message, which is otherwise sent back from TPC/IP port driver to sending client process, is now ignored earlier for distributed send operations.
Own Id: OTP-14689

Erts 9.1.5

Fixed Bugs and Malfunctions

Fixed a bug in file closure on Unix; close(2) was retried on EINTR which could cause a different (recently opened) file to be closed as well.
Own Id: OTP-14775
A race-condition when tearing down a connection with active node monitors could cause the runtime system to crash.
This bug was introduced in ERTS version 8.0 (OTP 19.0).
Own Id: OTP-14781 Aux Id: OTP-13047

Erts 9.1.4

Fixed Bugs and Malfunctions

Microstate accounting sometimes produced incorrect results for dirty schedulers.
Own Id: OTP-14707
Fixed a regression in zlib:gunzip/1 that prevented it from working when the decompressed size was a perfect multiple of 16384. This regression was introduced in 20.1.1
Own Id: OTP-14730 Aux Id: ERL-507
Fixed a memory corruption bug in enif_inspect_iovec; writable binaries stayed writable after entering the iovec.
Own Id: OTP-14745
Fixed a crash in enif_inspect_iovec on encountering empty binaries.
Own Id: OTP-14750
zlib:deflateParams/3 will no longer return buf_error when called after zlib:deflate/2 with zlib 1.2.11.
Own Id: OTP-14751

Erts 9.1.3

Fixed Bugs and Malfunctions

Added zlib:set_controlling_process/2 to move a zstream() between processes.
Own Id: OTP-14672 Aux Id: ERL-494
Fix so that schedulers are bound correctly when the first available cpu is not the first detected cpu. e.g. when using "taskset -c X..Y" when X is not equal to 0.
Own Id: OTP-14694

Erts 9.1.2

Fixed Bugs and Malfunctions

Fixed bug that could cause a VM crash when a corrupt message is received on distribution channel from other node.
Own Id: OTP-14661 Aux Id: ERIERL-80

Erts 9.1.1

Fixed Bugs and Malfunctions

The new zlib module returned a data_error when inflating concatenated streams, which was incompatible with the old module's behavior of returning the uncompressed data up to the end of the first stream.
Own Id: OTP-14648
zlib:gunzip/1 will no longer stop at the end of the first stream when decompressing concatenated gzip files.
Own Id: OTP-14649

Erts 9.1

Fixed Bugs and Malfunctions

Changed erlang:apply/2 to raise a badarg exception if the second argument is not a proper list. Previous behavior was a misleading undef exception.
Own Id: OTP-14490 Aux Id: ERL-432
On macOS, crypto would crash if observer had been started before crypto. On the beta for macOS 10.13 (High Sierra), crypto would crash. Both of those bugs have been fixed.
Own Id: OTP-14499 Aux Id: ERL-251 ERL-439
Fixed bug in enif_whereis_pid/port that could cause heap corruption in rare cases.
Own Id: OTP-14523
Fix so that trace messages generated when in a dirty nif are flushed correctly when the dirty nif is done executing.
Own Id: OTP-14538
Fix escape code handling when using ANSI color codes in the shell.
Own Id: OTP-14549 Aux Id: PR1536
Upgraded the ERTS internal PCRE library from version 8.40 to version 8.41. See http://pcre.org/original/changelog.txt for information about changes made to PCRE. This library implements major parts of the re regular expressions module.
Own Id: OTP-14574
Fixed a bug causing statistics(runtime) to produce negative values and a bug in statistics(wall_clock) causing it to produce values one second too long.
statistics(runtime) now also use getrusage() as source when available preventing the returned value from wrapping as frequent as before.
Own Id: OTP-14597 Aux Id: ERL-465
Fixed small memory leak that could occur when sending to a terminating port.
Own Id: OTP-14609
Fix bug causing VM crash when a module with -on_load directive is loaded while erlang:trace(on_load, ...) is enabled.
Own Id: OTP-14612
A warning that the compiler may optimize away atoms have been added to the documentation of list_to_existing_atom/1 and binary_to_existing_atom/2.
Own Id: OTP-14614 Aux Id: ERL-453

Improvements and New Features

Lock counting can now be fully toggled at runtime in the lock counting emulator (-emu_type lcnt). Everything is enabled by default to match the old behavior, but specific categories can be toggled at will with minimal runtime overhead when disabled. Refer to the documentation on lcnt:rt_mask/1 for details.
Own Id: OTP-13170
The zlib module has been refactored and all its operations will now yield appropriately, allowing them to be used freely in concurrent applications.
The following functions have been deprecated, but will not produce compiler warnings until OTP 21: zlib:adler32, zlib:crc32, zlib:inflateChunk, zlib:getBufSize, zlib:setBufSize.
The behavior of throwing an error when a dictionary is required for decompression has also been deprecated. Refer to the documentation on inflateSetDictionary/2 for details.
Own Id: OTP-14185
lcnt:collect and lcnt:clear will no longer block all other threads in the runtime system.
Own Id: OTP-14412
Add erlang:iolist_to_iovec/1, which converts an iolist() to an erlang:iovec(), which suitable for use with enif_inspect_iovec.
Own Id: OTP-14520
When provided with bad arguments, the zlib module will now raise named exceptions instead of just badarg. For example, not_initialized when using zlib:inflate/2 with an uninitialized stream.
Own Id: OTP-14527
erlang:halt/2 allows any Unicode string as slogan for the crash dump.
Own Id: OTP-14553
Add new nif API functions for managing an I/O Queue. The added functions are:
Own Id: OTP-14598

Erts 9.0.5

Fixed Bugs and Malfunctions

Fixed bug in binary_to_term and binary_to_atom that could cause VM crash. Typically happens when the last character of an UTF8 string is in the range 128 to 255, but truncated to only one byte. Bug exists in binary_to_term since ERTS version 5.10.2 (OTP_R16B01) and binary_to_atom since ERTS version 9.0 (OTP-20.0).
Own Id: OTP-14590 Aux Id: ERL-474

Erts 9.0.4

Fixed Bugs and Malfunctions

A timer internal bit-field used for storing scheduler id was too small. As a result, VM internal timer data structures could become inconsistent when using 1024 schedulers on the system. Note that systems with less than 1024 schedulers are not effected by this bug.
This bug was introduced in ERTS version 7.0 (OTP 18.0).
Own Id: OTP-14548 Aux Id: OTP-11997, ERL-468
Automatic cleanup of a BIF timer, when the owner process terminated, could race with the timeout of the timer. This could cause the VM internal data structures to become inconsistent which very likely caused a VM crash.
This bug was introduced in ERTS version 9.0 (OTP 20.0).
Own Id: OTP-14554 Aux Id: OTP-14356, ERL-468

Erts 9.0.3

Fixed Bugs and Malfunctions

Binary append operations did not check for overflow, resulting in nonsensical results when huge binaries were appended.
Own Id: OTP-14524

Erts 9.0.2

Fixed Bugs and Malfunctions

Added missing release notes for OTP-14491 ("performance bug in pre-allocators") which was included in erts-9.0.1 (OTP-20.0.1).
Own Id: OTP-14494
Fixed a bug that prevented TCP sockets from being closed properly on send timeouts.
Own Id: OTP-14509
Fixed bug in operator bxor causing erroneuos result when one operand is a big negative integer with the lowest N*W bits as zero and the other operand not larger than N*W bits. N is an integer of 1 or larger and W is 32 or 64 depending on word size.
Own Id: OTP-14514

Erts 9.0.1

Fixed Bugs and Malfunctions

Fixed a bug in gen_tcp:send where it never returned when repeatedly called on a remotely closed TCP socket.
Own Id: OTP-13939 Aux Id: ERL-193
Fixed segfault that could happen during cleanup of aborted erlang:port_command/3 calls. A port_command is aborted if the port is closed at the same time as the port_command was issued. This bug was introduced in erts-8.0.
Own Id: OTP-14481
Fixed implementation of statistics(wall_clock) and statistics(runtime) so that values do not unnecessarily wrap due to the emulator. Note that the values returned by statistics(runtime) may still wrap due to limitations in the underlying functionality provided by the operating system.
Own Id: OTP-14484
Fix performance bug in pre-allocators that could cause them to permanently fall back on normal more expensive memory allocation. Pre-allocators are used for quick allocation of short lived meta data used by messages and other scheduled tasks. Bug exists since OTP_R15B02. [this release note was missing in erts-9.0.1]
Own Id: OTP-14491

Erts 9.0

Fixed Bugs and Malfunctions

Fix various bugs regarding loading, upgrade and purge of HiPE compiled code:
- The native code memory for a purged module was never deallocated.
- Wrong functions could in some cases be called after a module upgrade.
- erlang:check_process_code did not check for recursive calls made from native code.
Own Id: OTP-13968
Hipe optional LLVM backend does require LLVM version 3.9 or later as older versions forced strong dependencies on erts internals structures.
Own Id: OTP-14238
When an exception such as 'throw(HugeTerm)' was caught, HugeTerm term would be kept in the process until the next exception occurred, potentially increasing the heap size for the process. That has been corrected.
Own Id: OTP-14255 Aux Id: OTP-14400, OTP-14401
Slogans in crash dumps have been extended to print more complex terms.
Own Id: OTP-14303
Fixed bug when using enif_inspect_binary in combination with enif_copy. In some circumstances the inspected binary could be reallocated by the enif_copy call when it shouldn't have been.
Own Id: OTP-14304
The address family local (AF_UNIX / AF_LOCAL) now does not ensure zero termination of Linux Abstract Addresses so they can use all bytes.
Own Id: OTP-14305
Use -fno-PIE for Gentoo Hardened and others that don't accept linker flag -no-pie.
Own Id: OTP-14307 Aux Id: PR-1379
Disable hipe for ppc64le architecture (little endian) as it is not, and has never been, supported. It was earlier equated with ppc64 (big endian) which lead to broken build without --disable-hipe.
Own Id: OTP-14314 Aux Id: ERL-369, PR-1394
Fix 'epmd -kill' to return a failure exit status code if epmd was not killed because of some error.
Own Id: OTP-14324
Fixed the following dirty scheduler related bugs:
- the +SDPcpu command line argument could cause the amount of dirty CPU schedulers to be set to zero
- erlang:system_flag(multi_scheduling, _) failed when only one normal scheduler was used together with dirty scheduler support
Own Id: OTP-14335
Fix erlexec to handle mismatch in sysconf and proc fs when figuring out the cpu topology. This behaviour has been seen when using docker together with --cpuset-cpus.
Own Id: OTP-14352
Fixed memory segment cache used for multiblock carriers. Huge (> 2GB) memory segments could cause a VM crash. Creation of such huge memory segments used for multiblock carriers is however very uncommon.
Own Id: OTP-14360 Aux Id: ERL-401, PR-1417
Fix bug causing code:is_module_native to falsely return true when local call trace is enabled for the module.
Own Id: OTP-14390
Fix emulator crash when receive tracing on a trace_delivered message.
Own Id: OTP-14411
Fix file:sendfile error handling on SunOS when a connection is closed during transmission.
Own Id: OTP-14424
escript did not handle paths with spaces correct.
Own Id: OTP-14433
Fix erroneous lock check assertion when wx is run on MacOS X.
Own Id: OTP-14437 Aux Id: ERL-360
Active-mode TCP sockets are now cleaned up properly on send/shutdown errors.
Own Id: OTP-14441 Aux Id: ERL-430
Fix compilation of hipe_mkliterals when the LIBS configure variable had to be set.
Own Id: OTP-14447

Improvements and New Features

Added erlang:garbage_collect/2 that takes an option list as the last argument that can be used to control whether a minor or a major garbage collection is to be done. Doing a minor collection only collects terms that have recently died, but is cheaper than a major collection.
Own Id: OTP-11695
Optimized test for tuples with an atom as first element.
Own Id: OTP-12148
Erlang literals are no longer copied during process to process messaging.
Own Id: OTP-13529
Add support in the erl_nif API for asynchronous message notifications when sockets or other file descriptors are ready to accept read or write operations. The following functions have been added:
- enif_select
- enif_monitor_process
- enif_demonitor_process
- enif_compare_monitors
- enif_open_resource_type_x
Own Id: OTP-13684
There are two new guard BIFs 'floor/1' and 'ceil/1'. They both return integers. In the 'math' module, there are two new BIFs with the same names that return floating point values.
Own Id: OTP-13692
Remove deprecated erlang:hash/2.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-13827
Replaced usage of deprecated symbolic time unit representations.
Own Id: OTP-13831 Aux Id: OTP-13735
Added support in zlib for extraction of the inflation dictionary.
Own Id: OTP-13842
The previously used purge strategy has been removed. The optional purge strategy introduced in ERTS version 8.1 is now the only strategy available.
The new purge strategy is slightly incompatible with the old strategy. Previously processes holding funs that referred to the module being purged either failed a soft purge, or was killed during a hard purge. The new strategy completely ignores funs. If funs referring to the code being purged exist, and are used after a purge, an exception will be raised upon usage. That is, the behavior will be exactly the same as the case when a fun is received by a process after the purge.
For more information see the documentation of erlang:check_process_code/3.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-13844 Aux Id: OTP-13833
Dirty schedulers are now enabled by default when the runtime system is built with SMP support.
Own Id: OTP-13860
Improved ETS lookup/insert/delete speed for large set, bag and duplicate_bag by a significant reduction of the hash load factor. This speed improvement comes at the expense of less than one word per table entry. Tables with less than 256 entries are not affected at all.
Own Id: OTP-13903
The NIF library reload feature is not supported anymore. It has been marked as deprecated since OTP R15B. This means that you are only allowed to do one successful call to erlang:load_nif/2 for each module instance. A second call to erlang:load_nif/2 will return {error, {reload, _}} even if the NIF library implements the reload callback.
Runtime upgrade of a NIF library is still supported by using the Erlang module upgrade mechanics with a current and an old module instance existing at the same time with their corresponding NIF libraries.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-13908
Add erlang:system_info(atom_count) and erlang:system_info(atom_limit) to provide a way to retrieve the current and maximum number of atoms.
Own Id: OTP-13976
The function fmod/2 has been added to the math module.
Own Id: OTP-14000
erlang:load_nif/2 returns new error type notsup when called for a HiPE compiled module, which is not supported.
Own Id: OTP-14002
Add driver and nif lock instrumentation to lcnt
Own Id: OTP-14069
Reduce memory pressure by converting sub-binaries to heap-binaries when possible. This is done during garbage collection.
Own Id: OTP-14149
Dirty schedulers are now enabled and supported on Erlang runtime systems with SMP support.
Besides support for dirty NIFs also support for dirty BIFs and dirty garbage collection have been introduced. All garbage collections that potentially will take a long time to complete are now performed on dirty schedulers if enabled.
erlang:statistics/1 with arguments inspecting scheduler and run queue states have been changed due to the dirty scheduler support. Code using this functionality may have to be rewritten taking these incompatibilities into consideration. Examples of such uses are calls to erlang:statistics(scheduler_wall_time), statistics(total_run_queue_lengths), statistics(total_active_tasks), etc.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-14152
Atoms may now contain arbitrary Unicode characters.
Own Id: OTP-14178
Introduce an event manager in Erlang to handle OS signals. A subset of OS signals may be subscribed to and those are described in the Kernel application.
Own Id: OTP-14186
The escript program now handles symbolic links to escripts.
This is useful for standalone systems with escripts residing on a bin directory not included in the execution path (as it may cause their erl program(s) to override the desired one). Instead the escripts can be referred to via symbolic links from a bin directory in the path.
Own Id: OTP-14201 Aux Id: PR-1293
All uses of the magic binary kludge has been replaced by uses of erlang references.
A magic binary was presented as an empty binary, but actually referred other data internally in the Erlang VM. Since they were presented as empty binaries, different magic binaries compared as equal, and also lost their internal data when passed out of an erlang node.
The new usage of references has not got any of these strange semantic issues, and the usage of these references has been optimized to give the same performance benefits as well as memory usage benefits as magic binaries had.
A couple of examples of previous uses of magic binaries are match specifications and NIF resources.
Own Id: OTP-14205
The non-smp emulators have been deprecated and are scheduled for removal in OTP-21.
In preparation for this, the threaded non-smp emulator is no longer built by default and has to be enabled using the --enable-plain-emulator to configure.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-14272
Allow HiPE to run on VM built with --enable-m32-build.
Own Id: OTP-14330 Aux Id: PR-1397
Upgraded the OTP internal PCRE library from version 8.33 to version 8.40. This library is used for implementation of the re regular expressions module.
Besides various bug fixes, the new version allows for better stack protection. In order to utilize this feature, the stack size of normal scheduler threads is now by default set to 128 kilo words on all platforms. The stack size of normal scheduler threads can be set upon system start by passing the +sss command line argument to the erl command.
See http://pcre.org/original/changelog.txt for information about changes made to PCRE between the versions 8.33 and 8.40.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-14331 Aux Id: ERL-208
Remove generation of atoms in old latin1 external format in the distribution between erlang nodes, erl_interface, and jinterface. The new utf8 format for atoms was introduced in OTP R16. An OTP 20 node can therefore not connect to nodes older than R16.
Atoms that can be encoded using latin1 are still encoded by term_to_binary() using latin1 encoding. Note that all atoms will by default be encoded using utf8 in a future Erlang/OTP release. For more information see the documentation of erlang:term_to_binary/2.
Own Id: OTP-14337
Added function re:version/0 which returns information about the OTP internal PCRE version used for implementation of the re module.
Own Id: OTP-14347 Aux Id: PR-1412
Added new debug bif erlang:list_to_port/1.
Own Id: OTP-14348
Various improvements of timer management internally in the VM. These improvements both reduced memory consumption of timer wheels as well as reduce the amount of work that has to be performed in order to handle timers.
Own Id: OTP-14356
Sockets can now be bound to device (SO_BINDTODEVICE) on platforms where it is supported.
This has been implemented e.g to support VRF-Lite under Linux; see VRF , and GitHub pull request #1326.
Own Id: OTP-14357 Aux Id: PR-1326
Added the following erl command line arguments with which you can set suggested stack for dirty schedulers:
- +sssdcpu - for dirty CPU schedulers
- +sssdio - for dirty IO schedulers
The default suggested stack size for dirty schedulers is 40 kilo words.
Own Id: OTP-14380
Changed erts startup program name, argv 0, to use the environment variable ESCRIPT_NAME so that erlc, dialyzer, typer, ct_run, or the escript name can be seen with external programs, such as ps and htop (depending on options), on unix.
Own Id: OTP-14381
Improvements of escript documentation.
Own Id: OTP-14384 Aux Id: OTP-14201
Add function enif_hash for NIFs to calculate hash values of arbitrary terms.
Own Id: OTP-14385 Aux Id: PR-1413
'./configure --enable-lock-counter' will enabling building of an additional emulator that has support for lock counting. (The option previously existed, but would turn on lock counting in the default emulator being built.) To start the lock-counting emulator, use 'erl -emu_type lcnt'.
On Windows, erl recognized the undocumented option -debug for starting a debug-compiled emulator. That option has been removed. Use 'erl -emu_type debug' instead.
Own Id: OTP-14407
Warnings have been added to the relevant documentation about not using un-secure distributed nodes in exposed environments.
Own Id: OTP-14425
Improvement of the documentation of the environment variable ERL_CRASH_DUMP_SECONDS as well as the default behavior when it is not set.
Own Id: OTP-14434
Enabled off-heap message queue for some system processes that might receive large amounts of messages.
Own Id: OTP-14438
ETS lock indexes have been replaced with the table name in LCNT results.
Own Id: OTP-14442 Aux Id: ERIERL-22
Introduced the new functions enif_whereis_pid() and enif_whereis_port().
Own Id: OTP-14453 Aux Id: PR-1400

Erts 8.3.5.7

Fixed Bugs and Malfunctions

Fixed bug in operator band of two negative operands causing erroneous result if the absolute value of one of the operands have the lowest N*W bits as zero and the other absolute value is not larger than N*W bits. N is an integer of 1 or larger and W is 32 or 64 depending on word size.
Own Id: OTP-15487 Aux Id: ERL-804

Improvements and New Features

Added an optional ./configure flag to compile the emulator with spectre mitigation: --with-spectre-mitigation
Note that this requires a recent version of GCC with support for spectre mitigation and the --mindirect-branch=thunk flag, such as 8.1.
Own Id: OTP-15430 Aux Id: ERIERL-237

Erts 8.3.5.6

Fixed Bugs and Malfunctions

Fixed small memory leak that could occur when sending to a terminating port.
Own Id: OTP-14609 Aux Id: ERIERL-238

Erts 8.3.5.5

Fixed Bugs and Malfunctions

Fixed a race condition in the inet driver that could cause receive to hang when the emulator was compiled with gcc 8.
Own Id: OTP-15158 Aux Id: ERL-654
Fixed a bug causing some Erlang references to be inconsistently ordered. This could for example cause failure to look up certain elements with references as keys in search data structures. This bug was introduced in R13B02.
Thanks to Simon Cornish for finding the bug and supplying a fix.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-15225

Erts 8.3.5.4

Fixed Bugs and Malfunctions

Fixed a bug in file closure on Unix; close(2) was retried on EINTR which could cause a different (recently opened) file to be closed as well.
Own Id: OTP-14775
A race-condition when tearing down a connection with active node monitors could cause the runtime system to crash.
This bug was introduced in ERTS version 8.0 (OTP 19.0).
Own Id: OTP-14781 Aux Id: OTP-13047

Erts 8.3.5.3

Fixed Bugs and Malfunctions

A timer internal bit-field used for storing scheduler id was too small. As a result, VM internal timer data structures could become inconsistent when using 1024 schedulers on the system. Note that systems with less than 1024 schedulers are not effected by this bug.
This bug was introduced in ERTS version 7.0 (OTP 18.0).
Own Id: OTP-14548 Aux Id: OTP-11997, ERL-468
Fixed bug in binary_to_term and binary_to_atom that could cause VM crash. Typically happens when the last character of an UTF8 string is in the range 128 to 255, but truncated to only one byte. Bug exists in binary_to_term since ERTS version 5.10.2 (OTP_R16B01) and binary_to_atom since ERTS version 9.0 (OTP-20.0).
Own Id: OTP-14590 Aux Id: ERL-474
Fix bug causing VM crash when a module with -on_load directive is loaded while erlang:trace(on_load, ...) is enabled.
Own Id: OTP-14612
Fixed bug that could cause a VM crash when a corrupt message is received on distribution channel from other node.
Own Id: OTP-14661 Aux Id: ERIERL-80

Erts 8.3.5.2

Fixed Bugs and Malfunctions

Fix performance bug in pre-allocators that could cause them to permanently fall back on normal more expensive memory allocation. Pre-allocators are used for quick allocation of short lived meta data used by messages and other scheduled tasks. Bug exists since OTP_R15B02.
Own Id: OTP-14491
Fixed a bug that prevented TCP sockets from being closed properly on send timeouts.
Own Id: OTP-14509
Fixed bug in operator bxor causing erroneuos result when one operand is a big negative integer with the lowest N*W bits as zero and the other operand not larger than N*W bits. N is an integer of 1 or larger and W is 32 or 64 depending on word size.
Own Id: OTP-14514

Erts 8.3.5.1

Fixed Bugs and Malfunctions

Fixed a bug in gen_tcp:send where it never returned when repeatedly called on a remotely closed TCP socket.
Own Id: OTP-13939 Aux Id: ERL-193
Fixed segfault that could happen during cleanup of aborted erlang:port_command/3 calls. A port_command is aborted if the port is closed at the same time as the port_command was issued. This bug was introduced in erts-8.0.
Own Id: OTP-14481
Fixed implementation of statistics(wall_clock) and statistics(runtime) so that values do not unnecessarily wrap due to the emulator. Note that the values returned by statistics(runtime) may still wrap due to limitations in the underlying functionality provided by the operating system.
Own Id: OTP-14484

Erts 8.3.5

Fixed Bugs and Malfunctions

Active-mode TCP sockets are now cleaned up properly on send/shutdown errors.
Own Id: OTP-14441 Aux Id: ERL-430
A code purge operation could under certain circumstances expand the size of hibernated processes.
Own Id: OTP-14444 Aux Id: ERIERL-24
Fix so that the ERL_ZZ_SIGTERM_KILL introduced in erts-8.3.4 works.
Own Id: OTP-14451

Erts 8.3.4

Fixed Bugs and Malfunctions

Add option to make SIGTERM trigger the OS default behaviour instead of doing a graceful shutdown. To activate this bahviour the environment variable ERL_ZZ_SIGTERM_KILL should be set to "true". This option only works in OTP 19 as OTP 20 will have a different way to deal with SIGTERM.
Own Id: OTP-14418 Aux Id: ERIERL-15

Erts 8.3.3

Fixed Bugs and Malfunctions

Fixed memory segment cache used for multiblock carriers. Huge (> 2GB) memory segments could cause a VM crash. Creation of such huge memory segments used for multiblock carriers is however very uncommon.
Own Id: OTP-14360 Aux Id: ERL-401, PR-1417
Fix release note for OTP-14290 in ERTS version 8.3.1. It was erroneously placed under "Known Bugs and Problems".
Own Id: OTP-14363 Aux Id: OTP-14290

Erts 8.3.2

Fixed Bugs and Malfunctions

The +Bi command line argument of erl erroneously caused SIGTERM to be ignored by the VM as well as of all its child processes. This bug was introduced in erts version 8.3.
Own Id: OTP-14358 Aux Id: OTP-14085

Erts 8.3.1

Fixed Bugs and Malfunctions

Invoking init:stop/0 via the SIGTERM signal, in a non-SMP BEAM, could cause BEAM to terminate with fatal error. This has now been fixed and the BEAM will terminate normally when SIGTERM is received.
Own Id: OTP-14290
Trying to open a directory with file:read_file/1 on Unix leaked a file descriptor. This bug has now been fixed.
Own Id: OTP-14308 Aux Id: ERL-383

Erts 8.3

Fixed Bugs and Malfunctions

Fixed a number of bugs that caused faulty stack-traces to be generated. The faulty stack traces were generated either when applying the following functions or tracing the following functions:
Own Id: OTP-14055
Corrected documentation about memory footprint for maps.
Own Id: OTP-14118
Fix process_info(Pid, current_stacktrace) to use stack depth limit set by system_flag(backtrace_depth). The old behavior was a hard coded depth limit of 8.
Own Id: OTP-14119 Aux Id: PR-1263
A process calling erlang:system_flag(multi_scheduling, block) could end up hanging forever in the call.
Own Id: OTP-14121
Dirty scheduler bug fixes:
- Fixed call time tracing of process being scheduled on dirty scheduler.
- GC info from dirty schedulers.
- Multi scheduling block with dirty schedulers could crash the runtime system.
- Process structures could be removed prematurely.
- GC on dirty scheduler could crash the runtime system.
- Termination of a process executing on a dirty scheduler could cause a runtime system crash.
Own Id: OTP-14122
Fixed crash that occurred when writing timer data to a crash dump.
Own Id: OTP-14133
A literal area could be removed while still referred from processes.
Own Id: OTP-14134
Fixed a bug in the garbage collector that could crash the runtime system.
Own Id: OTP-14135
Fixed a bug in call-time trace for NIFs which caused tracing to erroneously be started multiple times for one call.
Own Id: OTP-14136
Remove a debug printout and an unnecessary garbage collection when handling exceptions in hipe compiled code.
Own Id: OTP-14153
Fix bug in tracing of garbage collection that could cause VM crash. Bug exists since OTP 19.0.
Own Id: OTP-14154
Fix bug in binary_to_term for binaries created by term_to_binarywith option compressed. The bug can cause badarg exception for a valid binary when Erlang VM is linked against a zlib library of version 1.2.9 or newer. Bug exists since OTP 17.0.
Own Id: OTP-14159 Aux Id: ERL-340
Fix suspension of schedulers when generating a crashdump.
Own Id: OTP-14164
NIF resources was not handled in a thread-safe manner in the runtime system without SMP support.
As a consequence of this fix, the following driver functions are now thread-safe also in the runtime system without SMP support:
- driver_free_binary()
- driver_realloc_binary()
- driver_binary_get_refc()
- driver_binary_inc_refc()
- driver_binary_dec_refc()
Own Id: OTP-14202
Fix erlang:round/1 for large floating point numbers with an odd absolute value between (1 bsl 52) and (1 bsl 53). The result was falsely calculated as the next higher even number even though all integer values up to (1 bsl 53) can be represented as floats with full precision.
Own Id: OTP-14227
Add size of literals to module code size in crash dump and (l)oaded command in break menu like it used to be before OTP-19.0.
Own Id: OTP-14228
Fix potential bug in enif_send when called without a process context and with argument msg_env as NULL.
Own Id: OTP-14229
Fix bug where passing an appendable binary to erlang:port_control() could crash the emulator.
Own Id: OTP-14231
Receive expressions with timeout in the Erlang shell could cause a VM crash.
Own Id: OTP-14241 Aux Id: ERL-365

Improvements and New Features

A received SIGTERM signal to beam will generate a 'stop' message to the init process and terminate the Erlang VM nicely. This is equivalent to calling init:stop/0.
Own Id: OTP-14085
Workaround for buggy Android implementation of PTHREAD_STACK_MIN causing build of runtime system to crash on undeclared PAGE_SIZE.
Own Id: OTP-14165 Aux Id: ERL-319
Add configure option --without-thread-names that removes the naming of individual emulator threads.
Own Id: OTP-14234
Add warning in documentation of zlib:deflateInit/6 about option WindowsBits values 8 and -8.
Own Id: OTP-14254 Aux Id: ERL-362

Erts 8.2.2

Fixed Bugs and Malfunctions

Fix bug in binary_to_term for binaries created by term_to_binarywith option compressed. The bug can cause badarg exception for a valid binary when Erlang VM is linked against a zlib library of version 1.2.9 or newer. Bug exists since OTP 17.0.
Own Id: OTP-14159 Aux Id: ERL-340
The driver efile_drv when opening a file now use fstat() on the open file instead of stat() before opening, if fstat() exists. This avoids a race when the file happens to change between stat() and open().
Own Id: OTP-14184 Aux Id: seq-13266

Erts 8.2.1

Fixed Bugs and Malfunctions

Fix a quite rare bug causing VM crash during code loading and the use of export funs (fun M:F/A) of not yet loaded modules. Requires a very specific timing of concurrent scheduler threads. Has been seen on ARM but can probably also occurred on other architectures. Bug has existed since OTP R16.
Own Id: OTP-14144 Aux Id: seq13242

Erts 8.2

Fixed Bugs and Malfunctions

Fixed configure failures on MacOSX. Most important clock_gettime() was detected when building for MacOSX - El Capitan using XCode 8 despite it is not available until MacOSX - Sierra.
Own Id: OTP-13904 Aux Id: ERL-256
code:add_pathsa/1 and command line option -pa both revert the given list of directories when adding it at the beginning of the code path. This is now documented.
Own Id: OTP-13920 Aux Id: ERL-267
Fix a compilation error of erts in OpenBSD related to the usage of the __errno variable.
Own Id: OTP-13927
Fixed so that when enabling tracing on a process that had an invalid tracer associated with it, the new tracer overwrites the old tracer. Before this fix, calling erlang:trace/3 would behave as if the tracer was still alive and not apply the new trace.
This fault was introduced in ERTS 8.0.
Own Id: OTP-13928
Fix parsing of -profile_boot 'true' | 'false'
Own Id: OTP-13955 Aux Id: ERL-280
A slight improvement of erlang:get_stacktrace/0 for exceptions raised in hipe compiled code. Beam compiled functions in such stack trace was earlier replaced by some unrelated function. They are now instead omitted. This is an attempt to reduce the confusion in the absence of a complete and correct stack trace for mixed beam and hipe functions.
Own Id: OTP-13992
Correct type declaration of match specification head.
Own Id: OTP-13996
HiPE code loading failed for x86_64 if gcc was configured with --enable-default-pie. Fixed by disabling PIE, if needed for HiPE, when building the VM.
Own Id: OTP-14031 Aux Id: ERL-294, PR-1239
Faulty arguments could be presented on exception from a NIF that had rescheduled itself using enif_schedule_nif().
Own Id: OTP-14048
The runtime system could crash if a garbage collection on a process was performed immediately after a NIF had been rescheduled using enif_schedule_nif().
Own Id: OTP-14049
A reference to purged code could be left undetected by the purge operation if a process just had rescheduled a NIF call using enif_schedule_nif() when the process was checked. This could cause a runtime system crash.
Own Id: OTP-14050
Fixed a number of dirty scheduler related bugs:
- Process priority was not handled correct when scheduling on a dirty scheduler.
- The runtime system could crash when an exit signal with a compound exit reason was sent to a process executing on a dirty scheduler.
- The runtime system crashed when call tracing a process executing on a dirty scheduler.
- A code purge operation could end up hanging forever when a process executed on a dirty scheduler
Own Id: OTP-14051

Improvements and New Features

Fix minor soft purge race bug that could incorrectly trigger code_server to load new code for the module if the soft purge failed and no current version of the module existed.
Own Id: OTP-13925
To ease troubleshooting, erlang:load_nif/2 now includes the return value from a failed call to load/reload/upgrade in the text part of the error tuple. The crypto NIF makes use of this feature by returning the source line where/if the initialization fails.
Own Id: OTP-13951
New environment variable ERL_CRASH_DUMP_BYTES can be used to limit the size of crash dumps. If the limit is reached, crash dump generation is aborted and the generated file will be truncated.
Own Id: OTP-14046

Erts 8.1.1.1

Fixed Bugs and Malfunctions

A code purge operation could under certain circumstances expand the size of hibernated processes.
Own Id: OTP-14444 Aux Id: ERIERL-24

Erts 8.1.1

Fixed Bugs and Malfunctions

The emulator got a dynamic library dependency towards libsctp, which on Linux was not intended since the emulator there loads and resolves the needed sctp functions in runtime. This has been fixed and a configure switch --enable-sctp=lib has been added for those who want such a library dependency.
Own Id: OTP-13956 Aux Id: ERL-262, ERL-133
Fix SIGUSR1 crashdump generation
Do not generate a core when a crashdump is asked for.
Own Id: OTP-13997
The new functions in code that allows loading of many modules at once had a performance problem. While executing a helper function in the erl_prim_loader process, garbage messages were produced. The garbages messages were ignored and ultimately discarded, but there would be a negative impact on performance and memory usage. The number of garbage message depended on both the number of modules to be loaded and the length of the code path.
The functions affected of this problem were: atomic_load/1, ensure_modules_loaded/1, and prepare_loading/1.
Own Id: OTP-14009

Erts 8.1

Fixed Bugs and Malfunctions

Fix bug for calls from hipe code to BIFs that disable GC while yielding. Has been causing Dialyzer crashes on ARM (and presumably all other non-intel platforms).
Own Id: OTP-13724 Aux Id: PR-1116
Fix a bug where changing the current working directory of the VM would not change the current working directory of programs spawned using erlang:open_port({spawn,""}, ...).
Own Id: OTP-13733 Aux Id: ERL-175
Fix a bug where disabling tracing from a process that had return_to tracing enabled and was tracing on erlang:trace/3 would cause a segmentation fault.
Own Id: OTP-13734
Update all erts documentation to use simpler English, use consistent terminology and be easier to navigate.
Own Id: OTP-13740
Add dirty schedulers to the microstate accounting statistics.
Own Id: OTP-13744
Fixed dirty scheduler build support on 32-bit windows.
Own Id: OTP-13759
inet:getstat(Socket) on an SCTP socket returned 0 for send stats. This bug has now been corrected. Reported by systra as issue ERL-102 on bugs.erlang.org.
Own Id: OTP-13773 Aux Id: ERL-102
AF_UNSPEC and unknown address families were misread by UDP receive in prim_inet resulting in an exception. This bug has now been corrected.
Own Id: OTP-13775
Sweep HiPE stack for literals during code purge.
Own Id: OTP-13777 Aux Id: PR-1122
Fix bug in run_erl for OpenBSD that could cause it on rare occations to exit without starting the program (erl) at all.
Own Id: OTP-13795
Update build scripts to not make assumptions about where env, cp and perl are located.
Own Id: OTP-13800
Fixed a bug where init:stop could deadlock if a process with infinite shutdown timeout (e.g. a supervisor) attempted to load code while terminating.
Own Id: OTP-13802
Fixed a segmentation fault on sparc CPUs when free'ing a tracer module's state.
Own Id: OTP-13803
funs was not properly handled during purge of a module. This could cause a crash of the VM after a purge of a module.
Own Id: OTP-13809
Fixed a memory leak when the process monitoring a port crashed.
Own Id: OTP-13818
Fixed multiple dirty scheduler related tracing bugs.
Own Id: OTP-13822
Fix error handling in beam code runtime loader for a number of cases when index and size fields got corrupted (negative) values.
Own Id: OTP-13848 Aux Id: ERL-216
Minor fix of dirty scheduler implementation.
Own Id: OTP-13852
Calls to erl_drv_send_term() or erl_drv_output_term() from a non-scheduler thread while the corresponding port was invalid caused the emulator to enter an inconsistent state which eventually caused an emulator crash.
Own Id: OTP-13866
Fix a rare race condition in erlang:open_port({spawn, ""}, ...) that would result in the erl_child_setup program aborting and cause the emulator to exit.
Own Id: OTP-13868
Driver and NIF operations accessing processes or ports could cause an emulator crash when used from non-scheduler threads. Those operations are:
- erl_drv_send_term()
- driver_send_term()
- erl_drv_output_term()
- driver_output_term()
- enif_send()
- enif_port_command()
Own Id: OTP-13869
Fix start scripts generation dependency in Makefile
Own Id: OTP-13871 Aux Id: ERL-241
The VM could crash if erlang:get_stacktrace() was called after a rescheduled NIF had thrown an exception.
Own Id: OTP-13877
Calling code:delete/1 before a loading a module with an on_load function, the old code would be overwritten, causing a memory or a crash if NIFs were involved. (Thanks to vans163 for reporting this bug.)
Own Id: OTP-13893 Aux Id: ERL-240

Improvements and New Features

Improved accuracy of timeouts on MacOS X. This by setting premature timeouts followed by a short actual timeout during scheduler wait.
Own Id: OTP-13698
Added the following symbolic time unit representations to the erlang:time_unit/0 type:
- second
- millisecond
- microsecond
- nanosecond
The following symbolic time unit representations are now deprecated, but still part of the erlang:time_unit() type:
- seconds
- milli_seconds
- micro_seconds
- nano_seconds
Own Id: OTP-13735
Fix maps hashing entropy of maps with maps keys.
Own Id: OTP-13763 Aux Id: ERL-199
Improved dirty scheduler support. A purge of a module can now be performed without having to wait for completion of all ongoing dirty NIF calls.
Note that when enabling support for dirty schedulers, a new purge strategy will as of ERTS version 8.1 be enabled. This new strategy is not fully backwards compatible with the strategy used by default. For more information see the documentation of erlang:check_process_code/3.
Own Id: OTP-13808 Aux Id: OTP-13833
A new purge strategy has been introduced. The new strategy will by default be disabled during the OTP 19 release, but will be the only strategy available as of the OTP 20 release.
The new strategy is slightly incompatible with the strategy being used by default in OTP 19. Using the default strategy, processes holding funs that refer to the module being purged either fail a soft purge, or will be killed during a hard purge. The new strategy completely ignores funs. If funs referring to the code being purged exist, and are used after a purge, an exception will be raised upon usage. That is, the behavior will be exactly the same as the case when a fun is received by a process after the purge.
The new strategy can optionally be enabled when building OTP during OTP 19, and will automatically be enabled if the runtime system is built with support for dirty schedulers.
For more information see the documentation of erlang:check_process_code/3.
Own Id: OTP-13833
Fixed unnecessary overestimation of heap size need during garbage collection.
Own Id: OTP-13851

Erts 8.0.5

Fixed Bugs and Malfunctions

Fixed a VM crash that occurred in a garbage collection of a process when it had received binaries. This bug was introduced in ERTS version 8.0 (OTP 19.0).
Own Id: OTP-13890

Erts 8.0.4

Fixed Bugs and Malfunctions

Fixed a VM crash that occurred in garbage collection of a process when it had received maps over the distribution. This bug was introduced in ERTS version 8.0 (OTP 19.0).
Own Id: OTP-13889

Erts 8.0.3

Fixed Bugs and Malfunctions

Fixed a race that could cause a lost wakeup of a process that timed out in a receive ... after. This bug was introduced in ERTS version 7.0.
Own Id: OTP-13798 Aux Id: OTP-11997
Fixed segfault after writing an erl crash dump.
Own Id: OTP-13799

Erts 8.0.2

Fixed Bugs and Malfunctions

Fix scheduler deadlock bug in ets:update_counter/4 when key is not found and inserting the default object causes the table to grow.
Own Id: OTP-13731 Aux Id: ERL-188
Fix VM abort "Overrun stack and heap" in garbage collection triggered by a bsl operation and some very specific heap conditions.
Own Id: OTP-13732 Aux Id: seq13142

Erts 8.0.1

Fixed Bugs and Malfunctions

A memory allocation bug in group_leader/2 could cause an emulator crash when garbage collecting a process that had been assigned a remote group leader. This bug was introduced in ERTS version 8.0.
Own Id: OTP-13716

Erts 8.0

Fixed Bugs and Malfunctions

The handling of on_load functions has been improved. The major improvement is that if a code upgrade fails because the on_load function fails, the previous version of the module will now be retained.
Own Id: OTP-12593
is_builtin(erlang, apply, 3) will now return true.
Own Id: OTP-13034
Fix enif_get_list_length to return false if list is improper or have length larger than UINT_MAX (did return true and an incorrect length value).
Own Id: OTP-13288 Aux Id: PR913
Cleanup hipe signal handling code for x86 and make it more portable.
Own Id: OTP-13341 Aux Id: PR951
Make file:datasync use fsync instead of fdatasync on Mac OSX.
Own Id: OTP-13411
Make sure to create a crash dump when running out of memory. This was accidentally removed in the erts-7.3 release.
Own Id: OTP-13419
A bug has been fixed where if erlang was started +B on a unix platform it would be killed by a SIGUSR2 signal when creating a crash dump.
Own Id: OTP-13425
Fix race between process_flag(trap_exit,true) and a received exit signal.
A process could terminate due to exit signal even though process_flag(trap_exit,true) had returned. A very specific timing between call to process_flag/2 and exit signal from another scheduler was required for this to happen.
Own Id: OTP-13452
Don't search for non-existing Map keys twice
For maps:get/2,3 and maps:find/2, searching for an immediate key, e.g. an atom, in a small map, the search was performed twice if the key did not exist.
Own Id: OTP-13459
When an abnormally large distribution message is about to be sent, the VM has been changed to create a crash dump instead of a core dump.
Own Id: OTP-13474
Fix erlang:process_info/2 type specification
Own Id: OTP-13485 Aux Id: ERL-123
Fix bug in open_port/2 with option {args, List}. A vm crash could be caused by an improper List.
Own Id: OTP-13489 Aux Id: ERL-127
Fixed a race-condition bug where the emulator could crash when erlang:system_profile/1,2 was enabled and a process had to be re-scheduled during termination.
Own Id: OTP-13494 Aux Id: ERL-126
Fixed bugs where the reduction counter was not handled correct.
Own Id: OTP-13512
Fixed typo in description of the EPMD_DUMP_REQ response.
Own Id: OTP-13517
Fixed a bug where a process flagged as sensitive would sometimes record its save_calls when it shouldn't.
Own Id: OTP-13540
Update configure scripts to not use hard-coded path for /bin/pwd and /bin/rm.
Own Id: OTP-13562
When passing a larger binary than the outputv callback of a linked-in driver can handle in one io vector slot, the binary is now split into multiple slots in the io vector. This change only effects system where the max size of an io vector slot is smaller then the word size of the system (e.g. Windows).
This change means that it is now possible on Windows to send binaries that are larger than 4GB to port_command, which is what is used for file:write, gen_tcp:send etc.
Own Id: OTP-13628
Workaround of Maps output in crashdumps. Currently the atom 'undefined' is generated instead of Map data if a Map type is encountered during crash.
Own Id: OTP-13657

Improvements and New Features

The tracing support has been extended to allow a tracer module to be the trace event handler instead of a process or port. The tracer module makes it possible for trace tools to filter or manipulate trace event data without the trace event first having to be copied from the traced process or port.
With the introduction of this feature, erlang:trace(all|existing, _, _) now also returns the tracer process as part of the number of processes on which tracing is enabled. The is incompatible with the previous releases.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-10267
Introduce LTTng tracing of Erlang Runtime System
For LTTng to be enabled OTP needs to be built with configure option --with-dynamic-trace=lttng.
This feature introduces tracepoints for schedulers, drivers, memory carriers, memory and async thread pool.
For a list of all tracepoints, see Runtime Tools User's Guide .
Own Id: OTP-10282
Make it possible to monitor/demonitor ports using the erlang:monitor/2 API. The process and port information functions have also been updated to include information about monitors from processes to ports.
Own Id: OTP-11384
Add microstate accounting
Microstate accounting is a way to track which state the different threads within ERTS are in. The main usage area is to pin point performance bottlenecks by checking which states the threads are in and then from there figuring out why and where to optimize.
Since checking whether microstate accounting is on or off is relatively expensive only a few of the states are enabled by default and more states can be enabled through configure.
There is a convenience module called msacc that has been added to runtime_tools that can assist in gathering and interpreting the data from Microstate accounting.
For more information see erlang:statistics(microstateaccounting, ) and the msacc module in runtime_tools.
Own Id: OTP-12345
The port of Erlang/OTP to the real-time operating system OSE has been removed.
Own Id: OTP-12573
Sharing preserved copy for messages and exit signals
Enable sharing preserved copy with configure option --enable-sharing-preserving. This will preserve sharing, within the process, when communication with other processes in the Erlang node. There is a trade-off, the copy is more costly but this cost can be reclaimed if there is a lot of sharing in the message. In addition literals will not be copied in a send except during a purge phase of the module where the literals are located. This feature is considered experimental in 19.0.
Own Id: OTP-12590 Aux Id: OTP-10251
Halfword BEAM has been removed.
Own Id: OTP-12883
Added os:perf_counter/1.
The perf_counter is a very very cheap and high resolution timer that can be used to timestamp system events. It does not have monoticity guarantees, but should on most OS's expose a monotonous time.
Own Id: OTP-12908
Support for a fragmented young heap generation. That is, the young heap generation can consist of multiple non continuous memory areas. The main reason for this change is to avoid extra copying of messages that could not be allocated directly on the receivers heap.
Own Id: OTP-13047
Erlang linked-in driver can now force the call to open_port to block until a call to erl_drv_init_ack is made inside the driver. This is useful when you want to do some asynchronous initialization, for example getting configuration from a pipe, and you want the initial open_port call to fail if the configuration is incomplete or wrong. See the erl_driver documentation for more details on the API.
Own Id: OTP-13086
Erlang linked-in drivers can now set their own pids as seen in erlang:port_info/1 by using the erl_drv_set_pid function. For more details see the erl_driver documentation.
Own Id: OTP-13087
The functionality behind erlang:open_port/2 when called with spawn or spawn_executable has been redone so that the forking of the new program is done in a separate process called erl_child_setup. This allows for a much more robust implementation that uses less memory and does not block the entire emulator if the program to be started is on an un-accessible NFS. Benchmarks have shown this approach to be about 3-5 times as fast as the old approach where the fork/vfork was done by erts. This is a pure stability and performance fix, however some error messages may have changed, which is why it is marked as a backwards incompatible change.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-13088
Improved yielding strategy in the implementation of the following native functions:
- erlang:binary_to_list/1
- erlang:binary_to_list/3
- erlang:bitstring_to_list/1
- erlang:list_to_binary/1
- erlang:iolist_to_binary/1
- erlang:list_to_bitstring/1
- binary:list_to_bin/1
This in order to improve performance of these functions.
Own Id: OTP-13096
All garbage collections of processes now bump reductions. Also the amount of reductions bumped when garbage collecting has been adjusted. It now better corresponds to the amount of work performed. This in order to improve the real time characteristics of the system.
Own Id: OTP-13097
New functions that can load multiple modules at once have been added to the 'code' module. The functions are code:atomic_load/1, code:prepare_loading/1, code:finish_loading/1, and code:ensure_modules_loaded/1.
Own Id: OTP-13111
The -boot_var option for erl now only supports a single key and single value (as documented). The option used to allow multiple key/value pairs, but that behavior was undocumented.
The function erl_prim_loader:start/3 has been removed. Its documentation has also been removed.
The undocumented and unsupported function erl_prim_loader:get_files/2 has been removed.
Own Id: OTP-13112
Low level BIF erlang:purge_module/1 is made more robust against incorrect use. Lingering processes that still refer the old code are now killed before the module is purged to prevent fatal VM behavior.
Own Id: OTP-13122
Improved dirty scheduler implementation. For more information see the NIF documentation.
Note
- The dirty scheduler support is still experimental.
- The support for determining whether dirty NIF support exist or not at compile time using the C preprocessor macro ERL_NIF_DIRTY_SCHEDULER_SUPPORT has been removed.
- The enif_is_on_dirty_scheduler() function has been removed. Use enif_thread_type() instead.
Own Id: OTP-13123
Various optimizations done to process dictionary access.
Own Id: OTP-13167
Added max_heap_size process flag. max_heap_size allows the user to limit the maximum heap used by a process. See erlang:process_flag for more details.
Own Id: OTP-13174
Allow dynamic drivers and NIF libraries to be built with gcc option -fvisibility=hidden for faster loading and more optimized code.
Own Id: OTP-13227
Add erlang:process_info(Pid, garbage_collection_info) which returns extended garbage_collection information. For more details see the documentation.
Own Id: OTP-13265
The functions erlang:list_to_integer/1 and string:to_integer/1 have been optimized for large inputs.
Own Id: OTP-13293
Improved memory allocation strategy for hipe native code on x86_64 (amd64) architectures by reserving enough low virtual address space needed for the HiPE/AMD64 small code model. The default virtual address area for hipe code is set to 512Mb, but can be changed with emulator flag +MXscs.
Own Id: OTP-13359
Introduction of configurable management of data referred to by the message queue of a process. Each process can be configured individually.
It is now possible to configure the message queue of a process, so that all data referred by it will be kept outside of the heap, and by this prevent this data from being part of garbage collections.
For more information see the documentation of process_flag(message_queue_data, MQD).
Own Id: OTP-13366 Aux Id: OTP-13047
Processes now yield when scanning large message queues and not finding a matching message. This in order to improve real time characteristics.
Own Id: OTP-13401
Optimized an erts internal function that is used to traverse erlang terms. The internal function was mainly used by term_to_binary and comparison of terms. Benchmarks have shown up to a 10% performance increase in those functions after the optimization.
Own Id: OTP-13440
Add the following NIF API functions:
- enif_cpu_time
- enif_now_time
- enif_make_unique_integer
- enif_is_process_alive
- enif_is_port_alive
- enif_term_to_binary
- enif_binary_to_term
- enif_port_command
For details of what each function does, see the erl_nif documentation.
Own Id: OTP-13442
Optimize '++' operator and lists:append/2 by using a single pass to build a new list while checking for properness.
Own Id: OTP-13487
Handle terms (pids,ports and refs) from nodes with a 'creation' value larger than 3. This is a preparation of the distribution protocol to allow OTP 19 nodes to correctly communicate with future nodes (20 or higher). The 'creation' value differentiates different incarnations of the same node (name).
Own Id: OTP-13488
Don't send unasked for systemd notifications in epmd
Own Id: OTP-13493 Aux Id: PR-999
The enif_send API has been extended to allow NULL to be used as the message environment. When used this way, a message environment is implicitly created and the given term is copied into that environment before sending. This can be an optimization if many small messages are being sent by the nif.
Own Id: OTP-13495
The tracing support has been extended to allow tracing on ports. Ports can be traced on using the 'ports', 'send' and 'receive' trace flags.
The first argument of erlang:trace/3 has been extended so that 'all', 'existing' and 'new' now include both processes and ports. New Tracee variants, 'all_processes', 'all_ports', 'existing_processes' etc have been added to specify only processes or ports.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-13496
When the 'procs' trace flag is enabled, a 'spawned' trace event is now also generated by a newly created process. The previous event 'spawn' remains, but as it is generated by the process that did the spawn, it is not guaranteed that it is ordered with other trace events from the newly spawned process. So when tracking the lifetime of a process this new event should be used as the creation event.
This new trace event is marked as an incompatibility because tools that expect certain trace events when enabling 'procs' will have to updated.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-13497
Add the erlang:match_spec_test/3 function. The functions allows the testing of match specifications for both tracing and ets tables. It can be used to test that a match specification does the expected filtering on specific data. It also returns more verbose error reasons for incorrectly constructed match specifications.
Own Id: OTP-13501
The erts internal tracing support has been changed to have much less overhead and be more scalable.
This rewrite does not break any backwards incompatibilities, but it does change the ordering of some trace messages when compared to previous releases. It should be noted that this only applies to trace messages sent to processes or ports, it does not apply to the new tracer module. However in future releases they may also be effected by this.
Trace messages are only guaranteed to be ordered from one traced process or port. In previous releases this was not visible as a 'send' trace message would always arrive before the corresponding 'receive' trace message that is no longer always the case. This also means that timestamped trace messages may seem to arrive out of order as the timestamp is taken when the event is triggered and not when it is put in the queue of the tracer.
Own Id: OTP-13503
Add possibility to filter send and receive trace with match specifications.
Own Id: OTP-13507
Add maps:update_with/3,4 and maps:take/2
Own Id: OTP-13522 Aux Id: PR-1025
Introduce LTTng tracing via Erlang tracing.
For LTTng to be enabled OTP needs to be built with configure option --with-dynamic-trace=lttng.
The dynamic trace module dyntrace is now capable to be used as a LTTng sink for Erlang tracing. For a list of all tracepoints, see Runtime Tools User's Guide .
This feature also introduces an incompatible change in trace tags. The trace tags gc_start and gc_end has been split into gc_minor_start, gc_minor_end and gc_major_start, gc_major_end.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-13532
Print heap pointers for garbing processes during crashdump
Own Id: OTP-13541 Aux Id: PR-1026
Changed and improved low level memory statistics returned by erlang:system_info/1. The info for erts_mmap has been moved from mseg_alloc to its own section returned by {allocator, erts_mmap}.
Own Id: OTP-13560
Add enif_snprintf to the NIF API
The function enif_snprintf is similar to snprintf call but can handle formatting of Erlang terms via %T format specifier.
Own Id: OTP-13580
The warning in the documentation for erlang:raise/3 has been removed. It is now officially perfectly fine to use raise/3 in production code.
Own Id: OTP-13599
Fix bugs caused by the VM sometimes truncating object sizes or offsets to 32 bits on 64-bit hosts. These bugs were mainly found when working with large unicode strings and nifs environments.
Own Id: OTP-13606
Add -start_epmd command line option, this lets you disable automatic starting of epmd when starting a distributed node.
Add -epmd_module command line option, this lets you specify a module to register and look-up node names in. The default module is erl_epmd.
Own Id: OTP-13627
erlang:halt now truncates strings longer than 200 characters instead of failing with badarg.
Own Id: OTP-13630
Fix possible race in poller wake up on windows
Own Id: OTP-13634

Erts 7.3.1.6

Improvements and New Features

List subtraction (The -- operator) will now yield properly on large inputs.
Own Id: OTP-15371

Erts 7.3.1.5

Fixed Bugs and Malfunctions

Fixed small memory leak that could occur when sending to a terminating port.
Own Id: OTP-14609 Aux Id: ERIERL-238

Erts 7.3.1.4

Fixed Bugs and Malfunctions

Fix performance bug in pre-allocators that could cause them to permanently fall back on normal more expensive memory allocation. Pre-allocators are used for quick allocation of short lived meta data used by messages and other scheduled tasks. Bug exists since OTP_R15B02.
Own Id: OTP-14491
Fixed bug in operator bxor causing erroneuos result when one operand is a big negative integer with the lowest N*W bits as zero and the other operand not larger than N*W bits. N is an integer of 1 or larger and W is 32 or 64 depending on word size.
Own Id: OTP-14514
A timer internal bit-field used for storing scheduler id was too small. As a result, VM internal timer data structures could become inconsistent when using 1024 schedulers on the system. Note that systems with less than 1024 schedulers are not effected by this bug.
This bug was introduced in ERTS version 7.0 (OTP 18.0).
Own Id: OTP-14548 Aux Id: OTP-11997, ERL-468
Fixed bug in binary_to_term and binary_to_atom that could cause VM crash. Typically happens when the last character of an UTF8 string is in the range 128 to 255, but truncated to only one byte. Bug exists in binary_to_term since ERTS version 5.10.2 (OTP_R16B01) and binary_to_atom since ERTS version 9.0 (OTP-20.0).
Own Id: OTP-14590 Aux Id: ERL-474

Erts 7.3.1.3

Fixed Bugs and Malfunctions

A bug has been fixed where if erlang was started +B on a unix platform it would be killed by a SIGUSR2 signal when creating a crash dump.
Own Id: OTP-13425 Aux Id: ERL-94
Calls to erl_drv_send_term() or erl_drv_output_term() from a non-scheduler thread while the corresponding port was invalid caused the emulator to enter an inconsistent state which eventually caused an emulator crash.
Own Id: OTP-13866
Driver and NIF operations accessing processes or ports could cause an emulator crash when used from non-scheduler threads. Those operations are:
- erl_drv_send_term()
- driver_send_term()
- erl_drv_output_term()
- driver_output_term()
- enif_send()
- enif_port_command()
Own Id: OTP-13869
Fix bug in binary_to_term for binaries created by term_to_binarywith option compressed. The bug can cause badarg exception for a valid binary when Erlang VM is linked against a zlib library of version 1.2.9 or newer. Bug exists since OTP 17.0.
Own Id: OTP-14159 Aux Id: ERL-340

Erts 7.3.1.2

Fixed Bugs and Malfunctions

Fixed a race that could cause a lost wakeup of a process that timed out in a receive ... after. This bug was introduced in ERTS version 7.0.
Own Id: OTP-13798 Aux Id: OTP-11997
Fixed segfault after writing an erl crash dump.
Own Id: OTP-13799

Erts 7.3.1.1

Fixed Bugs and Malfunctions

Fix scheduler deadlock bug in ets:update_counter/4 when key is not found and inserting the default object causes the table to grow.
Own Id: OTP-13731 Aux Id: ERL-188

Erts 7.3.1

Fixed Bugs and Malfunctions

process_info(Pid, last_calls) did not work for Pid /= self().
Own Id: OTP-13418
Make sure to create a crash dump when running out of memory. This was accidentally removed in the erts-7.3 release.
Own Id: OTP-13419
Schedulers could be woken by a premature timeout on Linux. This premature wakeup was however harmless.
Own Id: OTP-13420
A process communicating with a port via one of the erlang:port_* BIFs could potentially end up in an inconsistent state if the port terminated during the communication. When this occurred the process could later block in a receive even though it had messages matching in its message queue.
This bug was introduced in erts version 5.10 (OTP R16A).
Own Id: OTP-13424 Aux Id: OTP-10336
The reference count of a process structure could under rare circumstances be erroneously managed. When this happened invalid memory accesses occurred.
Own Id: OTP-13446
Fix race between process_flag(trap_exit,true) and a received exit signal.
A process could terminate due to exit signal even though process_flag(trap_exit,true) had returned. A very specific timing between call to process_flag/2 and exit signal from another scheduler was required for this to happen.
Own Id: OTP-13452

Erts 7.3

Fixed Bugs and Malfunctions

The '-path' flag to 'erl' has been documented. This flag replaces the path specified in the boot script. It has always existed, but was earlier only documented in SASL (script).
Own Id: OTP-13060
The call_time tracing functionality internally used a time based on OS system time in order to measure call time which could cause erroneous results if OS system time was changed during tracing.
This functionality now use Erlang monotonic time in order to measure time. Besides fixing the erroneous results due to OS system time being used, the results are often also better since Erlang monotonic time often has better accuracy and precision.
Own Id: OTP-13216
Fix behaviour of -delay_write command line switch of epmd, which is used for debugging - in some cases epmd was sleeping twice the requested amount of time.
Own Id: OTP-13220
Fix race between timeout and exit signal that could cause a process to ignore the exit signal and continue execution. Bug exist since OTP 18.0.
Own Id: OTP-13245
Fix bug in erlang:halt/1,2 for large exit status values, causing either badarg (on 32-bit) or exit with a crash dump and/or core dump (on 64-bit). Make erlang:halt/1,2 tolerate any non negative integer as exit status and truncate high order bits if the OS does not support it.
Own Id: OTP-13251 Aux Id: ERL-49
gen_tcp:accept/2 was not time warp safe. This since it used the same time as returned by erlang:now/0 when calculating timeout. This has now been fixed.
Own Id: OTP-13254 Aux Id: OTP-11997, OTP-13222
Fix faulty error handling when writing to a compressed file.
Own Id: OTP-13270
Fix sendfile usage for large files on FreeBSD
Own Id: OTP-13271
Fix bug that could cause process_info(P,current_location) to crash emulator for hipe compiled modules.
Own Id: OTP-13282 Aux Id: ERL-79
Out of memory errors have been changed to cause an exit instead of abort.
Own Id: OTP-13292
When calling garbage_collect/[1,2] or check_process_code/[2,3] from a process with a higher priority than the priority of the process operated on, the run queues could end up in an inconsistent state. This bug has now been fixed.
Own Id: OTP-13298 Aux Id: OTP-11388
A workaround for an issue with older gcc versions (less than 5) and inline assembly on 32-bit x86 caused an emulator crash when it had been compiled with a newer gcc version. An improved configure test, run when building OTP, now detects whether the workaround should be used or not.
Own Id: OTP-13326 Aux Id: ERL-80

Improvements and New Features

Introduced new statistics functionality in order to more efficiently retrieve information about run able and active processes and ports. For more information see:
Own Id: OTP-13201
Time warp safety improvements.
Introduced the options monotonic_timestamp, and strict_monotonic_timestamp to the trace, sequential trace, and system profile functionality. This since the already existing timestamp option is not time warp safe.
Introduced the option safe_fixed_monotonic_time to ets:info/2 and dets:info/2. This since the already existing safe_fixed option is not time warp safe.
Own Id: OTP-13222 Aux Id: OTP-11997
Fix a register race where down nodes goes undetected in epmd
Own Id: OTP-13301
Improved the gcc inline assembly implementing double word atomic compare and exchange on x86/x86_64 so that it also can be used when compiling with clang.
Own Id: OTP-13336
An optimization preventing a long wait for a scheduler thread looking up information about a process executing on another scheduler thread had unintentionally been lost in erts-5.10 (OTP R16A). This optimization has now been reintroduced.
Own Id: OTP-13365 Aux Id: OTP-9892

Erts 7.2.1.1

Improvements and New Features

Introduced new statistics functionality in order to more efficiently retrieve information about run able and active processes and ports. For more information see:
Own Id: OTP-13201

Erts 7.2.1

Fixed Bugs and Malfunctions

Revert "Fix erroneous splitting of emulator path"
Own Id: OTP-13202
Fix HiPE enabled emulator for FreeBSD.
Own Id: OTP-13204 Aux Id: pr926

Erts 7.2

Fixed Bugs and Malfunctions

Small documentation fixes
Own Id: OTP-13017
Fix memory corruption bug caused by disabling distribution and then re-enable distribution with a node name that has previously been used by a remote node.
Own Id: OTP-13076 Aux Id: seq12959
Renamed variables with name bool as Visual Studio 2015 now treats this is a keyword.
Own Id: OTP-13079
erl_prim_loader has not supported custom loaders for several releases. In the documentation for erl_prim_loader, all references to custom loaders have now been removed.
Own Id: OTP-13102
Fixed compilation of erts together with libc versions that do not define __uint32_t.
Own Id: OTP-13105
erl -make now returns non-zero exit codes on failure
Own Id: OTP-13107
Fix crash on init:restart in embedded mode caused by on_load handler process not being relaunched leading to load failure for modules such as crypto and asn1rt_nif that need it to be present for correct NIF loading.
Own Id: OTP-13115
Fix maps decode in erlang:binary_to_term/1
Decoding a term with a large (HAMT) map in an small (FLAT) map could cause a critical error if the external format was not produced by beam.
Own Id: OTP-13125
Fix very rare bug in GC when big maps with a lot of hash collisions from a remote node are waiting in inner message queue.
Own Id: OTP-13146
Fixed a bug that could cause a crash dump to become almost empty.
Own Id: OTP-13150

Improvements and New Features

Updated the xmllint target to just check the xml files with real documentation content.
Corrected some errors and added some missing target in the DTD's.
Own Id: OTP-13026
Add function enif_getenv to read OS environment variables in a portable way from NIFs.
Own Id: OTP-13147

Erts 7.1

Fixed Bugs and Malfunctions

Fix bug in ETS that could cause stray objects marked for deletion to occasionally be missed by the cleanup done by safe_fixtable(_,false).
Own Id: OTP-12870
Fixed VM crash that could occur if a trace port was linked to a process, and the trace port terminated abnormally while handling a trace message. This bug has always existed in the runtime system with SMP support.
Own Id: OTP-12901
Instead of aborting, the vm now creates a crash dump when a system process is terminated.
Own Id: OTP-12934
Fixed a rare emulator dead lock that occurred when erlang:process_flag(priority,...) was called by a process that was also scheduled for an internal system activity.
Own Id: OTP-12943
The runtime system on various posix platforms (except for Linux and Solaris) could crash when large amounts of file-descriptors were in use.
Own Id: OTP-12954
A beam file compiled by hipe for an incompatible runtime system was sometimes not rejected by the loader, which could lead to vm crash. This fix will also allow the same hipe compiler to be used by both normal and debug-built vm.
Own Id: OTP-12962
Fix bug in maps:merge/2 when called by hipe compiled code that could cause vm crash. Bug exists since erts-7.0 (OTP 18.0).
Own Id: OTP-12965
When tracing with process_dump option, the VM could abort if there was an ongoing binary match somewhere in the call stack of the traced process.
Own Id: OTP-12968
Fixed possible output deadlock in tty driver when hitting "CTRL-C" in a non-smp emulator shell on unix.
Own Id: OTP-12987 Aux Id: Seq12947
Fix binary_to_integer to throw badarg for "+" and "-" similar to list_to_integer.
Own Id: OTP-12988
Suppress warning of unused argument when using macro enif_make_pid.
Own Id: OTP-12989

Improvements and New Features

Changed default clock source used for OS system time on MacOS X to gettimeofday() in order to improve performance. The system can be configured during build to use the previously used higher resolution clock source by passing the switch --with-clock-resolution=high when configuring the build.
Own Id: OTP-12945 Aux Id: OTP-12892
Added the configure option --disable-saved-compile-time which disables saving of compile date and time in the emulator binary.
Own Id: OTP-12971

Erts 7.0.3

Fixed Bugs and Malfunctions

Fixed a binary memory leak when printing to shell using the tty driver (i.e. not -oldshell).
Own Id: OTP-12941
Fix a bug where the standard error port sometimes crashes with eagain as the reason.
Own Id: OTP-12942
When tracing with process_dump option, the VM could abort if there was an ongoing binary match somewhere in the call stack of the traced process./
Own Id: OTP-12968

Erts 7.0.2

Fixed Bugs and Malfunctions

A process could end up in an inconsistent half exited state in the runtime system without SMP support. This could occur if the processes was traced by a port that it also was linked to, and the port terminated abnormally while handling a trace message for the process.
This bug has always existed in the runtime system without SMP support, but never in the runtime system with SMP support.
Own Id: OTP-12889 Aux Id: seq12885
Removed unnecessary copying of data when retrieving corrected Erlang monotonic time.
Own Id: OTP-12894
Changed default OS monotonic clock source chosen at build time. This in order to improve performance. The behavior will now on most systems be that (both OS and Erlang) monotonic time stops when the system is suspended.
If you prefer that monotonic time elapse during suspend of the machine, you can pass the command line argument --enable-prefer-elapsed-monotonic-time-during-suspend to configure when building Erlang/OTP. The configuration stage will try to find such a clock source, but might not be able to find it. Note that there might be a performance penalty associated with such a clock source.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-12895
erlang:system_info(end_time) returned a faulty value on 32-bit architectures.
Own Id: OTP-12896

Improvements and New Features

The configure command line argument --enable-gettimeofday-as-os-system-time has been added which force usage of gettimeofday() for OS system time. This will improve performance of os:system_time() and os:timestamp() on MacOS X, at the expense of worse accuracy, resolution and precision of Erlang monotonic time, Erlang system time, and OS system time.
Own Id: OTP-12892

Erts 7.0.1

Fixed Bugs and Malfunctions

Fix a rare hanging of the VM seen to happen just after emulator start. Bug exists since R14.
Own Id: OTP-12859 Aux Id: seq12882

Erts 7.0

Fixed Bugs and Malfunctions

Fix issuing with spaces and quoting in the arguments when using erlang:open_port spawn_executable on windows. The behavior now mimics how unix works. This change implies a backwards incompatibility for how spawn_executable works on windows.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-11905
Fix global call trace when hipe compiled code call beam compiled functions. Tracing of beam functions should now always work regardless who the caller is.
Own Id: OTP-11939
Correct cache alignment for ETS write_concurrency locks to improve performance by reduced false sharing. May increase memory footprint for tables with write_concurrency.
Own Id: OTP-11974
All possibly blocking operations in the fd/spawn and terminal driver have been converted to non-blocking operations. Before this fix it was possible for the VM to be blocked for a long time if the entity consuming stdout/stderr did not consume it fast enough.
Own Id: OTP-12239
Add missing overhead for offheap binaries created from external format. This fix can improve the garbage collection of large binaries originating from binary_to_term or messages from remote nodes.
Own Id: OTP-12554
Ensure hashing of zero is consistent
Erlang treats positive and negative zero as equal:
true = 0.0 =:= 0.0/-1
However, Erlangs hash functions: hash, phash and phash2 did not reflect this behaviour. The hash values produced by the different hash functions would not be identical for positive and negative zero.
This change ensures that hash value of positive zero is always produced regardless of the signedness of the zero float, i.e.,
true = erlang:phash2(0.0) =:= erlang:phash2(0.0/-1)
Own Id: OTP-12641
Ensure NIF term creation disallows illegal floating point values and too long atoms. Such values will cause a NIF to throw badarg exception when it returns.
Own Id: OTP-12655
Fixed building of Map results from match_specs
A faulty "box-value" entered into the heap which could cause a segmentation fault in the garbage collector if it was written on a heap fragment.
Own Id: OTP-12656
Fix hipe bug when matching a "writable" binary. The bug has been seen to sometimes cause a failed binary matching of a correct utf8 character, but other symptoms are also possible.
Own Id: OTP-12667
Keep dirty schedulers from waking other schedulers.
Own Id: OTP-12685
Disable floating point exceptions if the VM is compiled by clang/llvm. This is a known long-standing problem in clang/llvm.
Own Id: OTP-12717
Fix bug in file:sendfile for FreeBSD causing not the entire file to be sent.
Own Id: OTP-12720
Fix the broken Android support in erl_child_setup.c
Own Id: OTP-12751
Faulty statistics reported by the fix_alloc allocator.
Own Id: OTP-12766
Fix two erts_snprintf() calls to correct sizes.
- run_erl.c (ose): Use the size of the signal type, not its pointer. - erl_node_tables.c: Use the size of the _BUFFER in erts_snprintf() to make sure we can use the full space.
Own Id: OTP-12771
Delayed memory allocations could be delayed an unnecessarily long time.
Own Id: OTP-12812
Make sure that timeouts on a pool of acceptors are released in the correct order.
Own Id: OTP-12817
Fix segmentation fault in module_info for deleted modules
Own Id: OTP-12820
Fix garbage collection of literals in code purge
During code purging and check_process_code, the checking of the binary reference embedded in the match binary state was omitted for the tracing tests. This would cause the binary match state to reference deallocated memory.
Own Id: OTP-12821
A bug has been corrected for gen_tcp:close so when {linger,{true,0}} is in effect it does not wait for data in the driver queue to transfer out before closing the port. Bug fix by Rory Byrne.
Own Id: OTP-12840
The documentation of the driver callback start() erroneously stated that a return value of ERL_DRV_ERROR_ERRNO caused the error value to be passed via erl_errno when it should have been errno.
Own Id: OTP-12855

Improvements and New Features

Add md5 and module entries to ?MODULE:module_info/0/1 and remove obsolete entry 'import'.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-11940
Debug function erlang:display/1 shows content of binaries and bitstrings, not only the length.
Own Id: OTP-11941
The time functionality of Erlang has been extended. This both includes a new API for time, as well as time warp modes which alters the behavior of the system when system time changes. You are strongly encouraged to use the new API instead of the old API based on erlang:now/0. erlang:now/0 has been deprecated since it is and forever will be a scalability bottleneck. For more information see the Time and Time Correction chapter of the ERTS User's Guide.
Besides the API changes and time warp modes a lot of scalability and performance improvements regarding time management has been made internally in the runtime system. Examples of such improvements are scheduler specific timer wheels, scheduler specific BIF timer management, parallel retrieval of monotonic time and system time on systems with primitives that are not buggy.
Own Id: OTP-11997
erlang:function_exported(M, F, A) will now return true if M:F/A refers to a BIF.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-12099
New BIF: erlang:get_keys/0, lists all keys associated with the process dictionary. Note: erlang:get_keys/0 is auto-imported.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-12151 Aux Id: seq12521
Make distributed send of large messages yield to improve real-time characteristics.
Own Id: OTP-12232
Use high accuracy poll timeouts
Where available, use poll/select API's that can handle time resolutions less than 1ms. In the cases where such API's are not available the timeout is rounded up to the nearest ms.
Own Id: OTP-12236
The internal group to user_drv protocol has been changed to be synchronous in order to guarantee that output sent to a process implementing the user_drv protocol is printed before replying. This protocol is used by the standard_output device and the ssh application when acting as a client.
This change changes the previous unlimited buffer when printing to standard_io and other devices that end up in user_drv to 1KB.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-12240
The previously introduced "eager check I/O" feature is now enabled by default.
Eager check I/O can be disabled using the erl command line argument: +secio false
Characteristics impact compared to previous default:
- Lower latency and smoother management of externally triggered I/O operations.
- A slightly reduced priority of externally triggered I/O operations.
Own Id: OTP-12254 Aux Id: OTP-12117
Properly support maps in match_specs
Own Id: OTP-12270
The notice that a crashdump has been written has been moved to be printed before the crashdump is generated instead of afterwords. The wording of the notice has also been changed.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-12292
New function ets:take/2. Works the same as ets:delete/2 but also returns the deleted object(s).
Own Id: OTP-12309
Tracing with cpu_timestamp option has been enabled on Linux.
Own Id: OTP-12366
ets:info/1,2 now contains information about whether write_concurrency or read_concurrency is enabled.
Own Id: OTP-12376
Improved usage of gcc's builtins for atomic memory access. These are used when no other implementation of atomic memory operations is available. For example, when compiling for ARM when libatomic_ops is not available.
The largest improvement will be seen when compiling with a gcc with support for the __atomic_* builtins (using a gcc of at least version 4.7), but also when only the legacy __sync_* builtins are available (using a gcc of at least version 4.1) an improvement can be seen.
For more information see the "Atomic Memory Operations and the VM" section of $ERL_TOP/HOWTO/INSTALL.md.
Own Id: OTP-12383
Introduce math:log2/1 function to math module.
Own Id: OTP-12411
The documentation of the Abstract Format (in the ERTS User's Guide) has been updated with types and specification. (Thanks to Anthony Ramine.)
The explicit representation of parentheses used in types of the abstract format has been removed. Instead the new functions erl_parse:type_inop_prec() and erl_parse:type_preop_prec() can be used for inserting parentheses where needed.
Own Id: OTP-12492
Remove perfctr support
Development of perfctr in the linux kernel ceased in 2010. The perfctr support code in the Erlang VM is thus effectively dead code and therefore removed.
Own Id: OTP-12508
zlib:inflateChunk/2 has been added. It works like zlib:inflate/2, but decompresses no more data than will fit in the buffer configured by zlib:setBufSize/2.
Own Id: OTP-12548
Use linear search for small select_val arrays
Own Id: OTP-12555
New BIF ets:update_counter/4 with a default object as argument, which will be inserted in the table if the key was not found.
Own Id: OTP-12563
Export missing types from zlib module
Own Id: OTP-12584
Use persistent hashmaps for large Maps
Maps will use a persistent hashmap implementation when the number of pairs in a Map becomes sufficiently large. The change will occur when a Map reaches 33 pairs in size but this limit might change in the future.
The most significant impact for the user by this change is speed, and to a lesser degree memory consumption and introspection of Maps. Memory consumption size is probalistic but lesser than gb_trees or dict for instance. Any other impacts will be transparent for the user except for the following changes.
Semantics of Maps have changed in two incompatible ways compared to the experimental implementation in OTP 17:
- Hashing of maps is done different by erlang:phash2/1,2, erlang:phash/1 and erlang:hash/2.
- Comparing two maps with ==, /=, =<, <, >= and >, is done different if the keys contain floating point numbers.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-12585
Scalability improvement for erlang:make_ref/0, and other functionality that create references. Each scheduler now manage its own set of references. By this no communication at all is needed when creating references.
Previous implementation generated a strictly monotonically increasing sequence of references corresponding to creation time on the runtime system instance. This is not the case with current implementation. You can only expect reference to be unique. The Erlang/OTP documentation has never mentioned anything else but the uniqueness property, so this change is fully compatible. The only reason we've marked this as a potential incompatibility is since an early draft for an Erlang specification mentions strict monotonicity as a property.
If you need to create data with a strict monotonicity property use [erlang:uniqueinteger([monotonic])](erlang:unique_integer/1). Do _not use the deprecated erlang:now().
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-12610
Enable different abort signal from heart
By using environment variable HEART_KILL_SIGNAL, heart can now use a different signal to kill the old running Erlang.
By default the signal is SIGKILL but SIGABRT may also be used by setting environment variable: HEART_KILL_SIGNAL=SIGABRT
Own Id: OTP-12613 Aux Id: seq12826
Update autconf to latest version 2015-03-04
Own Id: OTP-12646
Optimization of timers internally in the VM. This include process timers (receive ... after), port timers (driver_set_timer()) as well as BIF timers (erlang:send_after()/erlang:start_timer()).
Each scheduler thread now has its own lock-free timer service instead of one locked central service. This dramatically improves performance of timer management on systems with a large amount of schedulers and timers.
The timer service internal data structure has also been optimized to be able to handle more timers than before. That is, each timer service is by its self able to handle more timers without dramatic performance loss than the old centralized timer service.
The API of BIF timers has also been extended. Timeout values are for example no longer limited to 32-bit integers. For more information see the documentation of erlang:start_timer/4, erlang:send_after/4, erlang:cancel_timer/2, and erlang:read_timer/2.
Characteristics impact: Calls to the synchronous versions of erlang:cancel_timer(), and erlang:read_timer() may take substantially longer time to complete than before. This occur when the timer that is accessed is managed by a remote scheduler. You typically want to use the new asynchronous option in order to avoid blocking the calling process.
Own Id: OTP-12650 Aux Id: OTP-11997
Specialize instructions from common assembler patterns
Specialize common instructions of rem, band, minus and plus in the beam loader. This will reduce the number of fetches and thus lessen the instruction dispatch pressure during runtime and speed up those operations in some common cases.
Specialize move patterns from x-registers to the stack with a new move_window instruction. This change will reduce instruction dispatch pressure.
Own Id: OTP-12690
Fix cross compilation for Android.
Own Id: OTP-12693
Fix incorrect use of autoconf macro AC_EGREP_CPP, which could cause faulty configuration if run from a path containing the string 'yes'.
Own Id: OTP-12706
Minimal Java version is now 1.6
Own Id: OTP-12715
Send format and args on process exit to error_logger
Previously, the emulator would generate a whole string with values and call the error_logger passing "~s~n". This changes it to a format string containing ~p with the respective values as arguments.
Own Id: OTP-12735
Map error logger warnings to warning messages by default.
Own Id: OTP-12755
Configure architecture ppc64le architecture as a ppc64
Own Id: OTP-12761
Add function enif_raise_exception to allow a NIF to raise an error exception with any type of reason.
Own Id: OTP-12770
Optimized node table statistics retrieval.
Own Id: OTP-12777
Map beam error logger warnings to warning messages by default. Previously these messages were mapped to the error channel by default.
Own Id: OTP-12781
gen_tcp:shutdown/2 is now asynchronous
This solves the following problems with the old implementation:
It doesn't block when the TCP peer is idle or slow. This is the expected behaviour when shutdown() is called: the caller needs to be able to continue reading from the socket, not be prevented from doing so.
It doesn't truncate the output. The current version of gen_tcp:shutdown/2 will truncate any outbound data in the driver queue after about 10 seconds if the TCP peer is idle of slow. Worse yet, it doesn't even inform anyone that the data has been truncated: 'ok' is returned to the caller; and a FIN rather than an RST is sent to the TCP peer.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-12797
Introduced delayed node table GC. This in order to avoid oscillation of entries in and out of the tables. The oscillation caused unnecessary lock contention on the table locks. The delay length can be set by passing the +zdntgc command line argument.
Characteristics impact: The tables can grow to very large sizes with unused entries if the node is get huge amounts of short lived connections from other nodes. This problem can be alleviated by shortening the length of the delay using the +zdntgc command line argument.
Own Id: OTP-12802
Improved implementation of erlang:statistics(io) in order to reduce contention between schedulers.
Characteristics impact: The actual call to erlang:statistics(io) takes longer time to complete, but the overall impact on the system is improved.
Own Id: OTP-12842
There are many cases where user code needs to be able to distinguish between a socket that was closed normally and one that was aborted. Setting the option {show_econnreset, true} enables the user to receive ECONNRESET errors on both active and passive sockets.
Own Id: OTP-12843
Do not preallocate too large event pool
A default pool size of 4000 is too excessive for the common case. This corresponds directly to the number of threads in the system. Change ERTS_TS_EV_ALLOC_DEFAULT_POOL_SIZE to 2048. Change ERTS_TS_EV_ALLOC_POOL_SIZE to 32.
Own Id: OTP-12849

Erts 6.4.1.7

Fixed Bugs and Malfunctions

A process communicating with a port via one of the erlang:port_* BIFs could potentially end up in an inconsistent state if the port terminated during the communication. When this occurred the process could later block in a receive even though it had messages matching in its message queue.
This bug was introduced in erts version 5.10 (OTP R16A).
Own Id: OTP-13424 Aux Id: OTP-10336
Calls to erl_drv_send_term() or erl_drv_output_term() from a non-scheduler thread while the corresponding port was invalid caused the emulator to enter an inconsistent state which eventually caused an emulator crash.
Own Id: OTP-13866
Driver and NIF operations accessing processes or ports could cause an emulator crash when used from non-scheduler threads. Those operations are:
- erl_drv_send_term()
- driver_send_term()
- erl_drv_output_term()
- driver_output_term()
- enif_send()
- enif_port_command()
Own Id: OTP-13869
Fix bug in binary_to_term for binaries created by term_to_binarywith option compressed. The bug can cause badarg exception for a valid binary when Erlang VM is linked against a zlib library of version 1.2.9 or newer. Bug exists since OTP 17.0.
Own Id: OTP-14159 Aux Id: ERL-340
Fixed bug in operator bxor causing erroneuos result when one operand is a big negative integer with the lowest N*W bits as zero and the other operand not larger than N*W bits. N is an integer of 1 or larger and W is 32 or 64 depending on word size.
Own Id: OTP-14514
Fixed bug in binary_to_term and binary_to_atom that could cause VM crash. Typically happens when the last character of an UTF8 string is in the range 128 to 255, but truncated to only one byte. Bug exists in binary_to_term since ERTS version 5.10.2 (OTP_R16B01) and binary_to_atom since ERTS version 9.0 (OTP-20.0).
Own Id: OTP-14590 Aux Id: ERL-474

Erts 6.4.1.6

Fixed Bugs and Malfunctions

When calling garbage_collect/[1,2] or check_process_code/[2,3] from a process with a higher priority than the priority of the process operated on, the run queues could end up in an inconsistent state. This bug has now been fixed.
Own Id: OTP-13298 Aux Id: OTP-11388

Erts 6.4.1.5

Fixed Bugs and Malfunctions

Fixed a bug that could cause a crash dump to become almost empty.
Own Id: OTP-13150

Erts 6.4.1.4

Fixed Bugs and Malfunctions

The 'raw' socket option could not be used multiple times in one call to any e.g gen_tcp function because only one of the occurrences were used. This bug has been fixed, and also a small bug concerning propagating error codes from within inet:setopts/2.
Own Id: OTP-11482 Aux Id: seq12872

Erts 6.4.1

Fixed Bugs and Malfunctions

The VTS mode in Common Test has been modified to use a private version of the Webtool application (ct_webtool).
Own Id: OTP-12704 Aux Id: OTP-10922

Erts 6.4

Fixed Bugs and Malfunctions

Fix missing quotation in the LM_FIND_EMU_CC autoconf macro which could cause build failures.
Own Id: OTP-12388
Fix erroneous printout of monitors in crashdump file.
Own Id: OTP-12537
The runtime system without SMP support could crash in the BIF port_control/3 if the port that was being accessed died during the call to the BIF.
Own Id: OTP-12544 Aux Id: Seq12777
Avoid corrupt oversized integer to be created from binary matching. Instead throw system_limit exception which is the correct behavior. A peculiar symptom of this bug was that bitwise operations (band, bor, bxor) on such oversized integers could return the empty list []. Credit: Mikael Pettersson, Nico Kruber
Own Id: OTP-12556
A race condition when calling port_info/1 could cause a memory fault has been fixed.
Own Id: OTP-12587
Fix comparison of exact terms. An overflow that could cause faulty comparisons has been fixed. Comparison of exact terms is exclusively used within Maps.
Own Id: OTP-12623
Fix bug in list_to_integer/1 for very long lists that could cause VM crash.
Own Id: OTP-12624

Improvements and New Features

Introduced a runtime system internal 64-bit API for atomic memory operations.
Own Id: OTP-12351
Add command line argument option for the initial size of process dictionaries.
Use '+hpds <size>' to set initial process dictionary size for spawned processes.
Own Id: OTP-12535 Aux Id: seq12809
Fix documentation on $char for Unicode
Own Id: OTP-12545

Erts 6.3.1

Fixed Bugs and Malfunctions

Fix getifaddrs realloc pointer error
When a buffer was exhausted and subsequently reallocated, we could get an unsafe pointer pointing to faulty memory.
For this to occur we would need to have a large number of interfaces and a reallocation of memory to a lower addresses.
The symptom would be garbage returned from erlang:port_control(Port, 25, []) (prim_inet:getifaddrs(Port) resulting in a badarg) or a segmentation fault.
Own Id: OTP-12445
Don't close all file descriptors twice in child_setup
The commit c2b4eab25c907f453a394d382c04cd04e6c06b49 introduced an error in which child_setup erroneously tried to close all file descriptors twice.
Use closefrom() if available when closing all file descriptors.
The function closefrom() was only used in the vfork() case before but is now also used in the fork() case if available.
Own Id: OTP-12446
During a crashdump all file descriptors are closed to ensure the closing of the epmd port and to reserve a file descriptor for the crashdump file.
If a driver (third party library) cannot handle closing of sockets this could result in a segmentation fault in which case a crashdump would not be produced. This is now fixed by only closing inets sockets via an emergency close callback to the driver and thus closing the epmd socket.
Own Id: OTP-12447

Erts 6.3

Fixed Bugs and Malfunctions

Fix HiPE debug lock checking on OS X 64bit
Position-independent code is mandatory on OS X. We use r11 as an intermediate register to fill BIF_P->hipe.bif_callee. This fixes the following error when doing `make debug FLAVOR=smp`:
clang -cc1as: fatal error: error in backend: 32-bit absolute addressing is not supported in 64-bit mode
Own Id: OTP-12188
Fix race bug that could cause VM crash in erlang:port_get_data/1 if the port was closed by a concurrent process. Also fix fatal bug if port_set_data/2 is called with a non-immediate data term. Both bugs exist since R16B01.
Own Id: OTP-12208
Correct make variable SSL_DED_LD_RUNTIME_LIBRARY_PATH when erl_xcomp_sysroot ends with a slash.
Own Id: OTP-12216 Aux Id: seq12700
Fix two cases of unreachable code caused by false use of assignment operators.
Own Id: OTP-12222
Fix bug when hipe compiled code makes tail call to a BIF that disables GC while trapping (sush as binary_to_list, list_to_binary, binary_to_term, term_to_binary).
Own Id: OTP-12231
Fix bug when a migrated empty memory carrier is reused just before it should be destroyed by the thread that created it.
Own Id: OTP-12249
Prevents compile-time errors in NIFs, when the compiler is instructed to treat missing field initializers as errors, by adding an initializer for the new options field which was added to ErlNifEntry for 17.3.
Own Id: OTP-12266
Fixed CPU topology detection on FreeBSD systems where Erlang/OTP is compiled by new C compilers (including, but possibly not limited to, gcc 4.9 and clang).
Own Id: OTP-12267
Use C99 function isfinite() instead of finite() when available on non GCC compilers.
Own Id: OTP-12268
Fix bug on windows where an incorrect number of links could be returned when doing file:read_file_info on a directory.
Own Id: OTP-12269
Fix rare bug when purging module on VM started with +Meamin.
Own Id: OTP-12273
Repair run_erl terminal window size adjustment sent from to_erl. This was broken in OTP 17.0 which could lead to strange cursor behaviour in the to_erl shell.
Own Id: OTP-12275 Aux Id: seq12739
Fixed bug on windows causing gen_tcp/udp to return an error when given an fd to work with.
Own Id: OTP-12289
Fix various internal erts issues where negating a signed integer in C would trigger undefined behavior. This fixes issues when dividing with bignums and list_to_integer.
Own Id: OTP-12290
When flushing output to stdout on windows, the emulator could sometimes hang indefinitely waiting for the flush to complete. This has been fixed.
Own Id: OTP-12291
Fix so that non-smp emulators with dirty scheduler support shows the correct number of dirty schedulers when calling erlang:system_info(system_version).
Own Id: OTP-12295
Add nif_version to erlang:system_info/1 in order to get the NIF API version of the runtime system in a way similar to driver_version.
Own Id: OTP-12298
Fix bug that could cause the return value from dirty NIF with zero arity to be treated as garbage, leading to VM crash.
Own Id: OTP-12300
Improve allocation carrier migration search logic. This will reduce the risk of failed migrations that could lead to excess memory consumption. It will also improve smp performance due to reduced memory contention on the migration pool.
Own Id: OTP-12323

Improvements and New Features

Introduced support for eager check I/O.
By default eager check I/O will be disabled, but this will most likely be changed in OTP 18. When eager check I/O is enabled, schedulers will more frequently check for I/O work. Outstanding I/O operations will however not be prioritized to the same extent as when eager check I/O is disabled.
Eager check I/O can be enabled using the erl command line argument: +secio true
Characteristics impact when enabled:
- Lower latency and smoother management of externally triggered I/O operations.
- A slightly reduced priority of externally triggered I/O operations.
Own Id: OTP-12117
Fix erts .app-file
Own Id: OTP-12189
Add configure option --with-ssl-incl=PATH to support OpenSSL installations with headers and libraries at different places.
Own Id: OTP-12215 Aux Id: seq12700
Optimization of atomic memory operations with release barrier semantics on 32-bit PowerPC when using the implementation included in OTP.
Own Id: OTP-12250
Minor adjustment of scheduler activation code making sure that an activation of a scheduler is not prevented by its run-queue being non-empty. (Thanks to Songlu Cai)
Own Id: OTP-12287
Improved support for atomic memory operations provided by the libatomic_ops library. Most importantly support for use of native double word atomics when implemented by libatomic_ops (for example, implemented for ARM).
The $ERL_TOP/HOWTO/INSTALL.md document now also more clearly describes when you want to build together with a libatomic_ops installation.
Own Id: OTP-12302
Add configure option --with-ssl-rpath to control which runtime library path to use for dynamic linkage toward OpenSSL.
Own Id: OTP-12316 Aux Id: seq12753
Added systemd notify support to epmd
Own Id: OTP-12321

Erts 6.2.1

Fixed Bugs and Malfunctions

Fix bug when an migrated empty memory carrier is reused just before it should be destroyed by the thread that created it.
Own Id: OTP-12249
Repair run_erl terminal window size adjustment sent from to_erl. This was broken in OTP 17.0 which could lead to strange cursor behaviour in the to_erl shell.
Own Id: OTP-12275 Aux Id: seq12739

Erts 6.2

Fixed Bugs and Malfunctions

General documentation updates.
Own Id: OTP-12052
A bug in the VM code implementing sending of signals to ports could cause the receiving port queue to remain in a busy state forever. When this state had been reached, processes sending command signals to the port either got suspended forever, or, if the nosuspend feature was used, always failed to send to the port. This bug was introduced in ERTS version 5.10.
In order for this bug to be triggered on a port, one had to at least once utilize the nosuspend functionality when passing a signal to the port. This by either calling
Thanks Vasily Demidenok for reporting the issue, and Sergey Kudryashov for providing a testcase.
Own Id: OTP-12082 Aux Id: OTP-10336
Fix size overflow bug at memory allocation. A memory allocation call, with an insane size close to the entire address space, could return successfully as if it had allocated just a few bytes. (Thanks to Don A. Bailey for reporting)
Own Id: OTP-12091
Fix various issues where negating a signed integer would trigger undefined behaviour. This fixes issues in the enif_make_int64 interface and some edge cases inside the erlang runtime system.
Own Id: OTP-12097
The documentation erroneously listed the +swct command line argument under +sws.
Own Id: OTP-12102 Aux Id: OTP-10994
Profiling messages could be delivered out of order when profiling on runnable_procs and/or runnable_ports using erlang:system_profile/2. This bug was introduced in ERTS version 5.10.
Own Id: OTP-12105 Aux Id: OTP-10336
Various logging fixes, including: Add run queue index to the process dump in crash dumps.
Add thread index to enomem slogan when crashing.
Remove error logger message for sending messages to old instances of the same node.
Own Id: OTP-12115
Fix compiler warnings reported by LLVM
Own Id: OTP-12138
Correct conversion of MIN_SMALL by list_to_integer/1 and binary_to_integer/1. The bug produced an unnormalized bignum which can cause strange behavior such as comparing different to a correct MIN_SMALL integer. The value MIN_SMALL is -(1 bsl 27) = -134217728 on a 32-bit VM and -(1 bsl 59) = -576460752303423488 on a 64-bit VM. (Thanks to Jesper Louis Andersen, Mikael Pettersson and Anthony Ramine for report, patch and optimization suggestion)
Own Id: OTP-12140
Fix bug in term_to_binary that reallocates binary with inconsistent size information. Bug has never been confirmed to be the cause of any faulty behavior.
Own Id: OTP-12141
Real_path method used while prim loading archive files was not taking into account the fact that windows directory symlinks can be across different drives.
Own Id: OTP-12155

Improvements and New Features

Add log2 histogram to lcnt for lock wait time
Own Id: OTP-12059
Introduced enif_schedule_nif() to the NIF API.
The enif_schedule_nif() function allows a long-running NIF to be broken into separate NIF invocations without the help of a wrapper function written in Erlang. The NIF first executes part of the long-running task, then calls enif_schedule_nif() to schedule a NIF for later execution to continue the task. Any number of NIFs can be scheduled in this manner, one after another. Since the emulator regains control between invocations, this helps avoid problems caused by native code tying up scheduler threads for too long.
The enif_schedule_nif() function also replaces the enif_schedule_dirty_nif() in the experimental dirty NIF API. Note that the only incompatible changes made are in the experimental dirty NIF API.
See the NIF documentation for more information.
Thanks to Steve Vinoski.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-12128

Erts 6.1.2

Fixed Bugs and Malfunctions

OTP-11850 fixed filelib:wildcard/1 to work with broken symlinks. This correction, however, introduced problems since symlinks were no longer followed for functions like filelib:ensure_dir/1, filelib:is_dir/1, filelib:file_size/1, etc. This is now corrected.
Own Id: OTP-12054 Aux Id: seq12660

Erts 6.1.1

Fixed Bugs and Malfunctions

Fixed ETHR_FORCE_INLINE which caused the build to break on some platforms without adequate thread support (VxWorks).
Own Id: OTP-12010

Erts 6.1

Fixed Bugs and Malfunctions

The documentation for spawn_opt/5 now has a note mentioning that the monitor option is not supported.
Own Id: OTP-11849
Fix broken system monitoring of large_heap for non-smp VM. No message for large_heap was ever sent on non-smp VM. Bug exist since R16B.
Own Id: OTP-11852
The emulator without SMP support crashed when passing a message to a process without enough heap space for the message. This bug was introduced in erts-6.0.
Own Id: OTP-11887 Aux Id: OTP-11388
Fix race between ETS table deletion and unfixation that could cause VM crash. The race could happen between a terminating process that does not own the table but has a fixation on it and another process that deletes the table (maybe the owner terminating) at the same time. Bug existed since R15B02.
Own Id: OTP-11892
The string following the -eval option when invoking erl would not be properly translated from UTF-8 to a list of Unicode characters (as would the arguments for -run).
That bug would cause the build of Erlang/OTP to fail when building in a directory whose pathname contained non-US ASCII characters encoded in UTF-8. (Thanks to Eric Pailleau for reporting this bug.)
Own Id: OTP-11916
Fix erts_debug:size/1 to handle Map sizes
Own Id: OTP-11923
Removed erlang:bitstr_to_list/1 and erlang:list_to_bitstr/1. They were added by mistake, and have always raised an undefined exception when called.
Own Id: OTP-11942
Fixed compilation using mingw-w64 on Windows.
Thanks to Jani Hakala.
Own Id: OTP-11945
The git sha is no longer printed in the shell start header when erlang is built from a tagged git release.
Own Id: OTP-11961
Fixed a bug where send trace events were erroneously dropped when the send was done to a registered process. This bug was introduced in R16B.
Own Id: OTP-11968

Improvements and New Features

The following native functions now bump an appropriate amount of reductions and yield when out of reductions:
Characteristics impact:
- Performance - The functions converting from lists got a performance loss for very small lists, and a performance gain for very large lists.
- Priority - Previously a process executing one of these functions effectively got an unfair priority boost. This priority boost depended on the input size. The larger the input was, the larger the priority boost got. This unfair priority boost is now lost.
Own Id: OTP-11888
The systemd features of epmd have been removed from epmd by default. To enable them you have to build erlang with the configure option --enable-systemd.
Own Id: OTP-11921
Removed Erlang wrapper code used when calling binary_to_term/1, and binary_to_term/2. This improves the performance of these BIFs especially when they are called with small binaries as input.
Own Id: OTP-11931
Add erlang:system_info(tolerant_timeofday), an API to check whether compensation for sudden changes of system time is enabled or not.
Own Id: OTP-11970

Erts 6.0.1

Fixed Bugs and Malfunctions

Fix broken system monitoring of large_heap for non-smp VM. No message for large_heap was ever sent on non-smp VM. Bug exist since R16B.
Own Id: OTP-11852
Fixed type spec of erlang:system_info/1.
Own Id: OTP-11859 Aux Id: OTP-11615

Erts 6.0

Fixed Bugs and Malfunctions

The option dupnames did not work as intended in re. When looking for names with {capture, [Name, ...]}, re:run returned a random instance of the match for that name, instead of the leftmost matching instance, which was what the documentation stated. This is now corrected to adhere to the documentation. The option {capture,all_names} along with a re:inspect/2 function is also added to further help in using named subpatterns.
Own Id: OTP-11205
Allow loading of NIF library with unicode path name
Own Id: OTP-11408
Allow loading of driver with unicode path name
Own Id: OTP-11549
Fixed a bug where starting Erlang without having an open stdin on fd 0 would sometimes deadlock the emulator when terminating.
Own Id: OTP-11558
The option '-names' in epmd now works on Windows (Thanks to Johannes Weißl)
Own Id: OTP-11565
Correction of the examples in escript documentation. (Thanks to Pierre Fenoll).
Own Id: OTP-11577
Fix bs_get_integer instruction
The instruction bs_get_integer could unnecessarily trigger a garbage collection in failure cases which is unwanted or outright dangerous.
Ex:
<<X:Sz,_/bits>> = <<"some binary">>
Previously, if Sz induced X to a bignum it would reserved memory size this on the heap via a garbage collection before checking if the size could actually match.
It will now check the binary size before triggering a collection.
Own Id: OTP-11581
Remove heap space overestimation in binary_to_term (and remote message reception) for integers in the intervals [-2147483648,-1] and [256,2147483647] on 64-bit emulators.
Own Id: OTP-11585
Add support for detecting the separate tinfo library from ncurses (Thanks to Dirkjan Ochtman)
Own Id: OTP-11590
Deprecation warning for system_flag(cpu_topology) has been extended for removal in OTP 18 (Thanks to Steve Vinoski for the update)
Own Id: OTP-11602
Documentation improvement regarding some awkward wording around the +spp flag. (Thanks to Brian L. Troutwine )
Own Id: OTP-11607
Fixed bug where sendfile would return the wrong error code for a remotely closed socket if the socket was in passive mode. (Thanks to Vincent Siliakus for reporting the bug.)
Own Id: OTP-11614
Increase garbage collection tenure rate
The garbage collector tries to maintain the previous heap block size during a minor gc, i.e. 'need' is not utilized in determining the size of the new heap, instead it relies on tenure and garbage to be sufficiently large.
In instances during intense growing with exclusively live data on the heap coupled with delayed tenure, fullsweeps would be triggered directly after a minor gc to make room for 'need' since the new heap would be full.
To remedy this, the tenure of terms on the minor heap will always happen (if it is below the high watermark) instead of every other minor gc.
Characteristics Impact: Reduced CPU-time spent in garbage collection but may infer delays in collecting garbage from the heap. Tweak 'fullsweep_after' options to increase gc pressure if needed.
Own Id: OTP-11617
Fix bug when comparing integers with floats larger than 2^992. The bug could potentially cause memory corruption on 32-bit emulators.
Own Id: OTP-11618
Cross-compilation fixes for TileraMDE-3.0.1.125620
Own Id: OTP-11635
sendfile no longer uses async threads by default
This has been done because a slow client attack is possible if the async thread pool is used. The scenario is:
Client does a request for a file and then slowly receives the file one byte at a time. This will eventually fill the async thread pool with blocking sendfile operations and thus starving the vm of all file operations.
If you still want to use the async threads pool for sendfile an option to enable it has been introduced.
Thanks to Christopher Faulet for identifying this vulnerability.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-11639
Do proper rollback of calls to enif_open_resource_type when load/upgrade callbacks of NIF library return failure.
Own Id: OTP-11722
Changed the default configuration when configuring with $ERL_TOP/configure to be the same as when configuring with $ERL_TOP/otp_build configure.
Previously floating point exceptions got enabled by default on Linux when HiPE was enabled when configuring with $ERL_TOP/configure, but not when configuring with $ERL_TOP/otp_build configure. The default is now in both cases not to use floating point exceptions since there still exist unresolved issues with floating point exceptions on Linux.
For more information see $ERL_TOP/HOWTO/INSTALL.md.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-11723
A comment in erl_db_tree.c no longer differ from the code. (Thanks to Cobus Carstens)
Own Id: OTP-11793
Fix epmd debug functionality for VxWorks (Thanks to Jay True)
Own Id: OTP-11808
Use closefrom/2 when available in child_setup (Thanks to Rick Reed and Anthony Ramine)
Own Id: OTP-11809
Fix dtrace/systemtap bug where the probe arguments would be concatenated due to faulty length calculation.
Thanks to Michal Ptaszek and Scott Lystig Fritchie
Own Id: OTP-11816
It is now better documented that the +fn* flags to erl also affect how command line parameters and environment variables are read. (Thanks to Vlad Dumitrescu)
Own Id: OTP-11818

Improvements and New Features

Options to set match_limit and match_limit_recursion are added to re:run. The option report_errors is also added to get more information when re:run fails due to limits or compilation errors.
Own Id: OTP-10285
Dialyzer's unmatched_return warnings have been corrected.
Own Id: OTP-10908
A common case is to wrap an argument to list_to_binary/1 in a list to ensure conversion can happen even though the argument may already be a binary. Take special care of this case and do not copy binary.
Impact: May cause incompatibility since a single binary is no longer copied. Use binary:copy/1,2 instead.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-11082
Make erlang:open_port/2 spawn and spawn_executable handle unicode.
Own Id: OTP-11105
Handle unicode (widestring) in erl, erlc, heart, etc on windows.
Own Id: OTP-11135
The version of the PCRE library Used by Erlang's re module is raised to 8.33 from 7.6. This means, among other things, better Unicode and Unicode Character Properties support. New options connected to PCRE 8.33 are also added to the re module (ucd, notempty_atstart, no_start_optimize). PCRE has extended the regular expression syntax between 7.6 and 8.33, why this imposes a potential incompatibility. Only very complicated regular expressions may be affected, but if you know you are using obscure features, please test run your regular expressions and verify that their behavior has not changed.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-11204
Filenames containing UTF-8 encoded characters can now be handled by erlc.
If you have set the ERLC_EMULATOR environment variable, note that erlc in OTP 17 will only work with erl in OTP 17 since the protocol between the erlc program and the erl_compile module has changed.
Own Id: OTP-11248
By giving --enable-static-{nifs,drivers} to configure it is now possible to statically linking of nifs and drivers to the main Erlang VM binary. At the moment only the asn1 and crypto nifs of the Erlang/OTP nifs and drivers have been prepared to be statically linked. For more details see the Installation Guide in the System documentation.
Own Id: OTP-11258
Erlang/OTP has been ported to the realtime operating system OSE. The port supports both smp and non-smp emulator. For details around the port and how to started see the User's Guide in the ose application.
Note that not all parts of Erlang/OTP has been ported.
Notable things that work are: non-smp and smp emulators, OSE signal interaction, crypto, asn1, run_erl/to_erl, tcp, epmd, distribution and most if not all non-os specific functionality of Erlang.
Notable things that does not work are: udp/sctp, os_mon, erl_interface, binding of schedulers.
Own Id: OTP-11334
Add the {active,N} socket option for TCP, UDP, and SCTP, where N is an integer in the range -32768..32767, to allow a caller to specify the number of data messages to be delivered to the controlling process. Once the socket's delivered message count either reaches 0 or is explicitly set to 0 with inet:setopts/2 or by including {active,0} as an option when the socket is created, the socket transitions to passive ({active, false}) mode and the socket's controlling process receives a message to inform it of the transition. TCP sockets receive {tcp_passive,Socket}, UDP sockets receive {udp_passive,Socket} and SCTP sockets receive {sctp_passive,Socket}.
The socket's delivered message counter defaults to 0, but it can be set using {active,N} via any gen_tcp, gen_udp, or gen_sctp function that takes socket options as arguments, or via inet:setopts/2. New N values are added to the socket's current counter value, and negative numbers can be used to reduce the counter value. Specifying a number that would cause the socket's counter value to go above 32767 causes an einval error. If a negative number is specified such that the counter value would become negative, the socket's counter value is set to 0 and the socket transitions to passive mode. If the counter value is already 0 and inet:setopts(Socket, [{active,0}]) is specified, the counter value remains at 0 but the appropriate passive mode transition message is generated for the socket.
Thanks to Steve Vinoski
Own Id: OTP-11368
A new optional scheduler utilization balancing mechanism has been introduced. For more information see the +sub command line argument.
Characteristics impact: None, when not enabled. When enabled, changed timing in the system, normally a small overhead due to measuring of utilization and calculating balancing information. On some systems, such as old Windows systems, the overhead can be quite substantial. This time measurement overhead highly depend on the underlying primitives provided by the OS.
Own Id: OTP-11385
A call to either the garbage_collect/1 BIF or the check_process_code/2 BIF may trigger garbage collection of another processes than the process calling the BIF. The previous implementations performed these kinds of garbage collections without considering the internal state of the process being garbage collected. In order to be able to more easily and more efficiently implement yielding native code, these types of garbage collections have been rewritten. A garbage collection like this is now triggered by an asynchronous request signal, the actual garbage collection is performed by the process being garbage collected itself, and finalized by a reply signal to the process issuing the request. Using this approach processes can disable garbage collection and yield without having to set up the heap in a state that can be garbage collected.
The garbage_collect/2, and check_process_code/3 BIFs have been introduced. Both taking an option list as last argument. Using these, one can issue asynchronous requests.
code:purge/1 and code:soft_purge/1 have been rewritten to utilize asynchronous check_process_code requests in order to parallelize work.
Characteristics impact: A call to the garbage_collect/1 BIF or the check_process_code/2 BIF will normally take longer time to complete while the system as a whole won't be as much negatively effected by the operation as before. A call to code:purge/1 and code:soft_purge/1 may complete faster or slower depending on the state of the system while the system as a whole won't be as much negatively effected by the operation as before.
Own Id: OTP-11388 Aux Id: OTP-11535, OTP-11648
Cleanup 'Buckets' and 'Time left' fields in crashdump to ease parsing.
Own Id: OTP-11419
Add sync option to file:open/2.
The sync option adds the POSIX O_SYNC flag to the open system call on platforms that support the flag or its equivalent, e.g., FILE_FLAG_WRITE_THROUGH on Windows. For platforms that don't support it, file:open/2 returns {error, enotsup} if the sync option is passed in. Thank to Steve Vinoski and Joseph Blomstedt
Own Id: OTP-11498
erlang:binary_to_term will now cost an appropriate amount of reductions and will interrupt (yield) for reschedule if the term is big. This avoids too long schedules when binary_to_term is used. (Thanks to Svante Karlsson for the original patch)
Impact: Programs running binary_to_term on large binaries will run more smoothly, but rescheduling will impact the single process performance of the BIF. Single threaded benchmarks might show degraded performance of the BIF, while general system behaviour will be improved.
Own Id: OTP-11535 Aux Id: OTP-11388
Added high resolution icon for windows. (Thanks to Daniel Goertz for the inspiration.)
Own Id: OTP-11560
Migration of memory carriers has been enabled by default on all ERTS internal memory allocators based on the alloc_util framework except for temp_alloc. That is, +M<S>acul de is default for these allocators. Note that this also implies changed allocation strategies for all of these allocators. They will all now use the "address order first fit carrier best fit" strategy.
By passing +Muacul 0 on the command line, all configuration changes made by this change will be reverted.
Characteristics impact: Improved memory characteristics with a smaller memory footprint at the expense of a quite small performance cost.
Own Id: OTP-11604 Aux Id: OTP-10279
A clarification has been added to the documentation of -on_load() in the Reference Manual that it is only recommended for loading NIF libraries.
Own Id: OTP-11611
+fnaw is now default when starting the emulator; it used to be +fnl.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-11612
EEP43: New data type - Maps
With Maps you may for instance:
- ____ - M0 = #{ a => 1, b => 2}, % create associations
- ____ - M1 = M0#{ a := 10 }, % update values
- ____ - M2 = M1#{ "hi" => "hello"}, % add new associations
- ____ - #{ "hi" := V1, a := V2, b := V3} = M2. % match keys with values
For information on how to use Maps please see Map Expressions in the Reference Manual.
The current implementation is without the following features:
- ____ - No variable keys
- ____ - No single value access
- ____ - No map comprehensions
Note that Maps is experimental during OTP 17.0.
Own Id: OTP-11616
The previously deprecated driver API function driver_async_cancel() has been removed. Due to this, the driver API version has been bumped to 3.0.
Thanks to Steve Vinoski.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-11628
Experimental "dirty scheduler" functionality has been introduced. In order to try the functionality out, you need to pass the command line argument --enable-dirty-schedulers to configure when building the system.
Dirty schedulers can currently only be used by NIFs on a system with SMP support. More information can be found in the erl_nif(3) documentation, the erl(1) documentation, and in the git commit comment of commit 'c1c03ae4ee50e58b7669ea88ec4d29c6b2b67c7b'.
Note that the functionality is experimental, and not supported. This functionality will be subject to backward incompatible changes. You should not enable the dirty scheduler functionality on production systems. It is only provided for testing.
Thanks to Steve Vinoski.
Own Id: OTP-11629
Improve reduction cost and yielding of term_to_binary. The reduction cost is increased and garbage collection is disabled during yield.
Impact: Improves system responsiveness when term_to_binary is called with large terms without significant degradation of single threaded performance.
Own Id: OTP-11648 Aux Id: OTP-11388
By default, the system's version of zlib will be used, provided its version is 1.2.4 or higher; otherwise the built-in zlib will be used. The built-in version of zlib has been bumped to 1.2.8. (Use the --enable-builtin-zlib option to configure to force the use of the built-in zlib.)
Own Id: OTP-11669
The default float encoding in binary_to_term and external_size has been changed to use minor_mode 1 instead of 0.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-11738
Introduced the configure option --with-assumed-cache-line-size=SIZE. For more information see $ERL_TOP/HOWTO/INSTALL.md.
Own Id: OTP-11742
Halfword emulator is marked as deprecated. It still works as before but is planned to be removed in a future major release.
Own Id: OTP-11777
The external format for Maps has changed in a way that is not compatible with the format used in OTP 17.0-rc1 and OTP 17.0-rc2.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-11782
Fixed faulty make dependency that would make some make versions fail while building gen_git_version.mk.
Own Id: OTP-11784
Introduced functionality for allowing old drivers and NIF libraries to be loaded during a transition period. For more information see the version management section in the erl_driver(3) documentation and the version management section in the erl_nif(3) documentation.
Own Id: OTP-11799
Support file paths longer than 259 characters on Windows. Long absolute paths are automatically converted to UNC format with a \\?\ prefix which is the only way to represent long paths. The 259 character limit still applies for individual file names, relative paths and the current working directory.
Own Id: OTP-11813
Document that escript:create/2 also accepts a 3-elements tuple containing files and zip:create/3 options to build a zip file.
Thanks to Pierre Fenoll
Own Id: OTP-11827
Add systemd socket activation for epmd.
Thanks to Matwey V. Kornilov
Own Id: OTP-11829

Erts 5.10.4.1

Known Bugs and Problems

When using gen_tcp:connect and the fd option with port and/or ip, the port and ip options were ignored. This has been fixed so that if port and/or ip is specified together with fd a bind is requested for that fd. If port and/or ip is not specified bind will not be called.
Own Id: OTP-12061

Erts 5.10.4

Fixed Bugs and Malfunctions

When normalizing paths, erl_prim_loader would always convert backslash to forward slash. This is correct on Windows, but not on other operating systems. erl_prim_loader now checks which OS is running before performing this conversion.
Own Id: OTP-11170
Fixed syslog defines and defined LOG_ERR for systems without syslog.h. Thanks to Matt Lewandowsky.
Own Id: OTP-11349
Check all pattern arguments passed to binary:matches/2. Thanks to Mike Sassak.
Own Id: OTP-11350
Fix two small silent rules omissions. Thanks to Anthony Ramine.
Own Id: OTP-11351
Teach configure to detect if posix_memalign cannot align to more than the system page size.
For cross-compiled systems a new environment variable called erl_xcomp_posix_memalign has been introduced to indicate whether posix_memalign should be used.
Own Id: OTP-11371
Fix bsr bug occurring when shifting a huge number a huge number of bits to the right. Thanks to Lars Hesel Christensen.
Own Id: OTP-11381
Fix memory leak for distributed monitors
Own Id: OTP-11410
Fix various typos in erts, kernel and ssh. Thanks to Martin Hässler.
Own Id: OTP-11414
Crashdumps initiated by out-of-memory on process spawn could cause the beam to segfault during crashdump writing due to invalid pointers.
The pointers are invalid since the process creation never finished. This fix removes these processes from the printouts. Reported by Richard Carlsson.
Own Id: OTP-11420
Crash dumps from 64-bit Erlang machines would have all memory addresses truncated to 32 bits, which could cause trouble inspecting processes message queues and stacks in the crashdump viewer.
Own Id: OTP-11450
Threads other than schedulers threads could make thread unsafe accesses when support for migration of memory carriers had been enabled, i.e., when the +M<S>acul command line flag had been passed to erl. This could cause corruption of the VMs internal state.
This bug was introduced in erts-5.10.2 when the support for migration of memory carriers was introduced.
Own Id: OTP-11456 Aux Id: OTP-10279
Fix bug in binary_to_term for invalid bitstrings and very large binaries (>2Gb).
Own Id: OTP-11479
Under rare circumstances a process calling inet:close/1, gen_tcp:close/1, gen_udp:close/1, or gen_sctp:close/1 could hang in the call indefinitely.
Own Id: OTP-11491
Fix bug that could cause a 32-bit emulator to always crash at start (since R16B01) depending on the alignment of static data in the beam executable.
Own Id: OTP-11496
Fix benign bugs regarding bitstring compare. Only a nuisance for debug and valgrind VM.
Own Id: OTP-11501
Silence warnings (Thanks to Anthony Ramine)
Own Id: OTP-11517
The default wordsize of the emulator (beam) is now determined by compiler default on Mac OSX (Darwin). This was previously forced to 32bits by the configure script unless otherwise specified.
Own Id: OTP-11521

Improvements and New Features

A new memory allocation feature called "super carrier" has been introduced. The super carrier feature can be used in different ways. It can for example be used for pre-allocation of all memory that the runtime system should be able to use.
By default the super carrier is disabled. It is enabled by passing the +MMscs <size in MB> command line argument. For more information see the documentation of the +MMsco, +MMscrfsd, +MMscrpm, +MMscs, +MMusac, and, +Mlpm command line arguments in the erts_alloc(3) documentation.
Since it is disabled by default there should be no impact on system characteristics if not used.
This change has been marked as a potential incompatibility since the returned list when calling erlang:system_info({allocator, mseg_alloc}) now also include an {erts_mmap, _} tuple as one element in the list.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-11149
Added erlang:system_info(ets_limit) to provide a way to retrieve the runtime's maximum number of ETS tables. Thanks to Steve Vinoski
Own Id: OTP-11362
Add new BIF os:unsetenv/1 which deletes an environment variable. Thanks to Martin Hässler.
Own Id: OTP-11446
Introduced a new guarantee regarding exit signals from ports:
If the process calling one of the synchronous port BIFs listed below is linked to the port identified by the first argument, and the port exits before sending the result of the port operation, the exit signal issued due to this link will be received by the processes before the BIF returns, or fail with an exception due to the port not being open.
The synchronous port BIFs are:
Note that some ports under certain circumstances unlink themselves from the calling process before exiting, i.e. even though the process linked itself to the port there might be no link triggering an exit signal.
Characteristics impact: The return or exception from the synchronous port BIF will be delayed if the port simultaneously exit due to some issue unrelated to the outstanding synchronous port BIF call. In all other cases characteristics are unchanged.
Own Id: OTP-11489

Erts 5.10.3.1

Improvements and New Features

Memory allocators will be able to create sys_alloc carriers as fallback, if mseg_alloc cannot create more carriers, on systems with posix_memalign() support. This is similar to how it worked in pre-R16 releases.
Windows systems will create carriers using _aligned_malloc() and can by this use the new optimized allocator header scheme introduced in R16 on other platforms.
Own Id: OTP-11318

Erts 5.10.3

Fixed Bugs and Malfunctions

The documentation of predefined types and built-in types has been corrected.
Own Id: OTP-11090
Fix changing terminal parameters in to_erl
Change the behaviour of to_erl to use TCSADRAIN instead of TCSANOW when changing terminal parameters. This makes the serial driver wait for the output queues to be empty before applying the terminal parameter change. Thanks to Stefan Zegenhagen.
Own Id: OTP-11206
The default value of {flush, boolean()} in erlang:halt/2 is documented to be 'true' if the status is an integer. The implementation behaviour was reversed. The Implementation is now corrected to adhere to the documentation. Thanks to Jose Valim for reporting the error.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-11218
Fix serious race bug in R16B01 that could cause PID mix-ups when a lot of processes were spawned and terminated in a very rapid pace on an SMP emulator with at least two scheduler threads.
Own Id: OTP-11225
Validating a trace pattern with the option silent no longer incorrectly enables/disables the silent option of the calling process.
Own Id: OTP-11232
Fixed a bug where GCC 4.8 and later use a more aggressive loop optimization algorithm that broke some previously working code in the efile driver. Thanks to Tomas Abrahamsson for reporting this issue.
Own Id: OTP-11246
Fixed bug when printing memory allocator acul option in crash dump.
Own Id: OTP-11264
Opening a new compressed file on Windows could in rare (random) cases result in {error,eisdir} or other error codes although it should have succeeded. This is now corrected.
Own Id: OTP-11265
Fixed a race condition when closing a trace port that would cause the emulator to crash.
Own Id: OTP-11290

Improvements and New Features

There is a new somewhat experimental socket option 'netns' that can set the network namespace for a socket on Linux:es where it is supported. See the documentation.
Own Id: OTP-11157
New allocator strategy aoffcbf (address order first fit carrier best fit). Supports carrier migration but with better CPU performance than aoffcaobf.
Own Id: OTP-11174
Introduced functionality for inspection of system and build configuration.
Own Id: OTP-11196
Fix matching of floating point middle-endian machines. Thanks to Johannes Weissl.
Own Id: OTP-11201
Fix compile error on ARM and GCC versions greater than 4.1.0. Thanks to Johannes Weissl.
Own Id: OTP-11214
run_erl: Redirect standard streams to /dev/null. Thanks to Johannes Weissl.
Own Id: OTP-11215
Misc. corrections in documentation for erl_driver. Thanks to Giacomo Olgeni.
Own Id: OTP-11227
Fix documentation regarding binary_part.
Own Id: OTP-11239
Make edlin understand a few important control keys. Thanks to Stefan Zegenhagen.
Own Id: OTP-11251
Export type zlib:zstream/0. Thanks to Loic Hoguin.
Own Id: OTP-11278
Add erl option to set schedulers by percentages.
For applications where measurements show enhanced performance from the use of a non-default number of emulator scheduler threads, having to accurately set the right number of scheduler threads across multiple hosts each with different numbers of logical processors is difficult because the erl +S option requires absolute numbers of scheduler threads and scheduler threads online to be specified.
To address this issue, add a +SP option to erl, similar to the existing +S option but allowing the number of scheduler threads and scheduler threads online to be set as percentages of logical processors configured and logical processors available, respectively. For example, "+SP 50:25" sets the number of scheduler threads to 50% of the logical processors configured, and the number of scheduler threads online to 25% of the logical processors available. The +SP option also interacts with any settings specified with the +S option, such that the combination of options "+S 4:4 +SP 50:50" (in either order) results in 2 scheduler threads and 2 scheduler threads online.
Thanks to Steve Vinoski
Own Id: OTP-11282
Extend erl_driver interface with lock names
Lock and thread names are already a feature in the driver interface. This extension will let developers read these names which eases debugging.
Own Id: OTP-11303
Fix incorrect values returned by integer_to_binary/2. Thanks to Juan Jose Comellas.
Own Id: OTP-11311
Fix system_flag scheduling_statistics - disable . Thanks to Steve Vinoski.
Own Id: OTP-11317
The documentation of predefined types has been corrected Thanks to Kostis Sagonas.
Own Id: OTP-11321

Erts 5.10.2

Fixed Bugs and Malfunctions

A bug in prim_inet has been corrected. If the port owner was killed at a bad time while closing the socket port the port could become orphaned hence causing port and socket leaking. Reported by Fred Herbert, Dmitry Belyaev and others.
Own Id: OTP-10497 Aux Id: OTP-10562
Compilation fixes for NetBSD. Thanks to YAMAMOTO Takashi.
Own Id: OTP-10941
Fixed a race condition when using delayed_write when writing to a file which would cause the same data to be written multiple times.
Own Id: OTP-10984
Fix small memory leak from tracing with option meta.
Own Id: OTP-10997
Correct typo in erlsrv usage. Thanks to Bryan Hunter
Own Id: OTP-11002
ct_run: delete unused function. Thanks to Tuncer Ayaz.
Own Id: OTP-11003
Corrections to run_erl/to_erl handshake behaviour.
Own Id: OTP-11012
Fix typo in type: erlang:process_info_item(). Thanks to Andrew Tunnell-Jones.
Own Id: OTP-11024
Fix src/dest overlap issue in ttsl driver. Thanks to Steve Vinoski.
Own Id: OTP-11064
When sending to a port using erlang:send(Port, Msg, [nosuspend]), the send operation was performed synchronously. This bug has now been fixed.
Own Id: OTP-11076 Aux Id: OTP-10336
When converting a faulty binary to a list with unicode:characters_to_list, the error return value could contain a faulty "rest", i.e. the io_list of characters that could not be converted was wrong. This happened only if input was a sub binary and conversion was from utf8. This is now corrected.
Own Id: OTP-11080
Runtime system could crash when reporting stale driver_select().
Own Id: OTP-11084
Fix lock order violation for memory instrumentation (+Mim, +Mis, +Mit).
Own Id: OTP-11085
Fixed some compilation warnings on miscellaneous platforms. Thanks to Anthony Ramine.
Own Id: OTP-11086
Fixed issue when flushing i/o during shutdown on windows where the Erlang VM would sometime hang due to a race condition.
Own Id: OTP-11096
Fixed issue where repeated calls to erlang:nodes() could cause unnecessary contention in the dist_table lock.
Own Id: OTP-11097
Properly guard WIDE_TAG use with HAVE_WCWIDTH in ttsl_drv. Thanks to Anthony Ramine
Own Id: OTP-11106
Fix some Makefile rules that didn't support silent rules. Thanks to Anthony Ramine.
Own Id: OTP-11111
Fix receive support in erl_eval with a BEAM module. Thanks to Anthony Ramine.
Own Id: OTP-11137
erlang:now() could suddenly jump ~24 days into the future on Windows. This is now corrected. Thanks to Garret Smith for reporting and testing fixes.
Own Id: OTP-11146
erlang:term_to_binary will now cost an appropriate amount of reductions and will interrupt (yield) for reschedule if the term is big. This avoids too long schedules when term_to_binary is used.
Impact: Programs running term_to_binary on large terms will run more smothly, but rescheduling will impact the single process performance of the BIF. Single threaded benchmarks will show degraded performance of the BIF when called with very large terms, while general system behaviour will be improved. The overhead for allowing restart and reduction counting also degrades local performance of the BIF with between 5% and 10% even for small terms.
Own Id: OTP-11163

Improvements and New Features

Replaced the lock protecting gathering of garbage collection statistics with a lock-free solution.
Own Id: OTP-10271 Aux Id: kunagi-108 [04c5410f-9cc4-4696-8639-36bf98686c7a-7]
Support for migration of memory carriers between memory allocator instances has been introduced.
By default this feature is not enabled and do not effect the characteristics of the system. When enabled it has the following impact on the characteristics of the system:
- Reduced memory footprint when the memory load is unevenly distributed between scheduler specific allocator instances.
- Depending on the default allocation strategy used on a specific allocator there might or might not be a slight performance loss.
- When enabled on the fix_alloc allocator, a different strategy for management of fix blocks will be used.
- The information returned from erlang:system_info({allocator, A}), and erlang:system_info({allocator_sizes, A}) will be slightly different when this feature has been enabled. An mbcs_pool tuple will be present giving information about abandoned carriers, and in the fix_alloc case no fix_types tuple will be present.
For more information, see the documentation of the +M<S>acul command line argument.
Own Id: OTP-10279
Change specs for spawn_opt to use the process_level() type declaration instead of re-defining it in various places. Thanks to Kostis Sagonas.
Own Id: OTP-11008
Postscript files no longer needed for the generation of PDF files have been removed.
Own Id: OTP-11016
Erlang source files with non-ASCII characters are now encoded in UTF-8 (instead of latin1).
Own Id: OTP-11041 Aux Id: OTP-10907
Optimization of simultaneous inet_db operations on the same socket by using a lock free implementation.
Impact on the characteristics of the system: Improved performance.
Own Id: OTP-11074
The high_msgq_watermark and low_msgq_watermark inet socket options introduced in OTP-R16A could only be set on TCP sockets. These options are now generic and can be set on all types of sockets.
Own Id: OTP-11075 Aux Id: OTP-10336
A new better algorithm for management of the process, and port tables has been introduced.
Impact on the characteristics of the system:
- The new algorithm ensures that both insert and delete operations can be made in O(1) time complexity. Previously used algorithm either caused insert or delete to be O(N).
- The new algorithm will also ensure that reuse of identifiers will be less frequent than when the old algorithm was used.
- Previously used algorithm ensured that the latest created identifier compared as the largest when comparing two identifiers of the same type that had been created on the same node as long as no identifiers had been reused. Since identifiers can be reused quite fast, one has never been able to rely on this property. Due to the introduction of this new algorithm this property will not hold even if no identifiers has been reused yet. This could be considered as an incompatibility.
Due to the above mensioned potential incompatibility, it will still be possible to enable the old algorithm for some time. The command line argument +P legacy will enable the old algorithm on the process table, and +Q legacy will do the same for the port table. These command line arguments are however deprecated as of their introduction and have been scheduled for removal in OTP-R18.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-11077
Support wide characters in the shell through wcwidth(). Thanks to Anthony Ramine. Reported by Loïc Hoguin.
Own Id: OTP-11088
Added total used memory for each process in erlang crash dumps.
Own Id: OTP-11098
Added support for hipe on Raspberry Pi (armv6l). Thanks to Klaus Alfert.
Own Id: OTP-11125
Remove 'query' from the list of reserved words in docs. Thanks to Matthias Endler and Loïc Hoguin.
Own Id: OTP-11158
Lift static limitation (FD_SETSIZE) for file descriptors on Mac OS X. (Thanks to Anthony Ramine)
Own Id: OTP-11159

Known Bugs and Problems

Miscellaneous native code in OTP misbehave either due to lengthy execution, or due to not bumping reductions properly. Problems typically occur when passing huge sets of data to a misbehaving BIF. Fixing this has high priority and is being worked on, but there will remain issues like this for some time.
In order to alleviate problems with scheduling which might occur when executing misbehaving native code, the command line argument +sfwi has been introduced.
By default this feature is disabled and you are advised not to enable it if you do not encounter problems with misbehaving native code.
When enabled it has the following impact on the characteristics of the system:
- Work will always be distributed between schedulers even when executing misbehaving native code.
- It may cause an increased amount of processes and/or ports bouncing between schedulers which in turn will cause a performance loss.
- It may cause reduced performance due to reduced or lost work compaction when all schedulers do not execute under full load.
- An increased contention on run queue locks.
Own Id: OTP-11164

Erts 5.10.1.2

Fixed Bugs and Malfunctions

A bug in the implementation of offline schedulers has been fixed. The bug was introduced in OTP-R16A/ERTS-5.10, and caused work-stealing between schedulers to fail. This in turn, caused work to accumulate in some run-queues. The bug was only triggered when there were offline schedulers in the system, i.e., when the amount of online schedulers was less than the total amount of schedulers. The effect of the bug got more severe the larger amount of offline schedulers the system had.
Own Id: OTP-11022 Aux Id: OTP-9892

Erts 5.10.1.1

Fixed Bugs and Malfunctions

The BIF is_process_alive/1 could prematurely return false while the process being inspected was terminating. This bug was introduced in ERTS-5.10.
Own Id: OTP-10926
Fix a problem in erlang:delete_element/2 where the call could corrupt one word of stack if the heap and stack met during call.
Own Id: OTP-10932
The +sws<value> and +swt<value> system flags failed if no white space were passed between the parameter and value parts of the flags. Upon failure, the runtime system refused to start.
Own Id: OTP-11000

Improvements and New Features

Scheduler threads will now by default be less eager requesting wakeup due to certain cleanup operations. This can also be controlled using the +swct command line argument of erl(1).
Own Id: OTP-10994

Erts 5.10.1

Fixed Bugs and Malfunctions

Threads created internally in the runtime system by vanilla, fd, and spawn drivers on Windows systems could make thread unsafe calls to driver_select().
Own Id: OTP-10802
Threads created internally in the runtime system by the vanilla, fd, and spawn drivers on Windows systems could make unsafe memory accesses to driver data after port had terminated.
Own Id: OTP-10803
The runtime system could crash when flushing data to standard out or standard error on Windows.
Own Id: OTP-10807
Bugs due to the port optimizations introduced in erts-5.10/OTP-R16A have been fixed:
- Memory leak when terminating ports
- Memory leak when reaching the system limit of maximum amount of concurrently existing ports
- Crashes due to missing, or late test of bad port handle
- The newly introduced driver API function erl_drv_busy_msgq_limits() could not be used by dynamically linked in drivers on Windows
Own Id: OTP-10809 Aux Id: OTP-10336
Fix {packet,httph} header capitalization for unrecognized header fields longer than 20 characters such as Sec-Websocket-Version. The limit is simply raised from 20 to 50 characters with the hope that valid headers longer than 50 are not used.
Own Id: OTP-10824
Fix rounding issues in float_to_list/1,2. Thanks to Serge Aleynikov
Own Id: OTP-10837
Fix memory leak in file driver introduced in R16A.
Own Id: OTP-10841
A bug in an ERTS internal queue implementation could cause the loss of a wake up signal to a consumer thread. This has now been fixed.
The effect of this bug, when triggered, was often only a small or even no delay of certain operations. This since, threads often are woken due to other unrelated reasons. However, if the consumer thread was not woken due to other reasons when the bug was triggered, these operations could be left hanging, potentially for ever. Such effects seems to have been very rare, but we have on at least one occasion gotten a report about such an issue.
Operations potentially effected by this bug:
- Inspection of memory allocation status - The Erlang process calling erlang:memory/[0,1], or erlang:system_info({allocator|allocator_sizes, _}) could potentially hang waiting for responses from involved threads.
- Async thread pool jobs - An async thread pool job request and/or reply could potentially be left hanging. In OTP this only effected file operations, but user implemented drivers using the async thread pool were also effected. In the file operation case, this would typically translate into an Erlang process potentially hanging on the file operation.
- Shutting down the runtime system - Due to the issue with the async thread pool mentioned above, flushing of I/O while terminating the runtime system could also potentially hang.
- ETS memory deallocation - Scheduled jobs handling deallocation of the main structure of an ETS table could potentially hang. This more or less only translates into minor memory leaks.
- Shutting down distribution - The distribution shutdown phase used when manually shutting down the distribution, i.e., when calling net_kernel:stop(), could potentially hang.
Own Id: OTP-10854
OS X Snow Leopard now only uses write, as writev does not work properly on very large files.
Own Id: OTP-10858
Fixed a bug where line oriented file I/O using read_ahead was very slow for files with very large difference in line length.
Own Id: OTP-10859
In erts-5.10 (R16A) faulty hashvalues were produced for non-ASCII atoms (characters in byte-range 128..255). This has now been fixed and hashvalues conforms to previous OTP releases.
Own Id: OTP-10860
Fixes of memory accesses that might be thread unsafe when the runtime system has been linked against third-party libraries for atomic memory operations during the build. Most builds are uneffected by this bug. If triggered, the runtime system will most likely crash more or less immediately.
Own Id: OTP-10875 Aux Id: OTP-10854
Fixed a bug where it was longer possible to give the +sws proposal flag to non-smp emulators.
Own Id: OTP-10881 Aux Id: seq12258
Faulty type to bytes read for ReadFile on Windows. This could cause windows systems to misbehave. The correct type is now used.
Own Id: OTP-10890
Change default max ports for Windows to 8192. Having a too large value caused Windows to not be able to recover properly. If you want to use another value, pass +Q Value to erl or werl.
Own Id: OTP-10892
Fix rare crash on halfword vm during code loading.
Own Id: OTP-10896

Improvements and New Features

Tuple funs (deprecated in R15B) are no longer supported.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-10170
Added four new bifs, erlang:binary_to_integer/1,2, erlang:integer_to_binary/1, erlang:binary_to_float/1 and erlang:float_to_binary/1,2. These bifs work similarly to how their list counterparts work, except they operate on binaries. In most cases converting from and to binaries is faster than converting from and to lists.
These bifs are auto-imported into erlang source files and can therefore be used without the erlang prefix.
Own Id: OTP-10300 Aux Id: kunagi-74 [74]
The experimental support for packages has been removed.
Own Id: OTP-10348 Aux Id: kunagi-316 [227]
The driver API function erl_drv_consume_timeslice(), and the NIF API function enif_consume_timeslice() have been introduced.
These functions are provided in order to better support co-operative scheduling, improve system responsiveness, and to make it easier to prevent misbehaviors of the VM due to a process or port monopolizing a scheduler thread. They can be used when dividing lengthy work into a number of repeated calls without the need to use threads.
Own Id: OTP-10810
The list_to_integer/2 bif has been optimized when used with bases other than 10.
Own Id: OTP-10834 Aux Id: kunagi-74 [74]
The git commit sha of the HEAD commit is now added to the Erlang shell when compiling a non-released Erlang version.
Own Id: OTP-10838
Change caching policy for memory segment allocator. For instance, prefer sbc segments over mbc segments, caching policy is time-arrow aware, evicting older cached segments to store newer segments.
The default number of cacheable segment has been increased from five to ten segments. This can be modified, same as before, with the command line option +MMmcs 5
Impact: Increased speed for processing on larger objects, e.g. binaries. Slight increase of mapped and resident memory. Tune your system with memory options to erl for best performance.
Own Id: OTP-10840
Updated config.sub and config.guess to latest version from gnu.org
Own Id: OTP-10848
Add an xcomp file for Blue Gene/Q. Thanks to Kostis Sagonas.
Own Id: OTP-10849
Cleanup of documentation of the type language. Thanks to Kostis Sagonas.
Own Id: OTP-10850
Change the return value of hipe_bifs:remove_refs_from/1. Thanks to Kostis Sagonas.
Own Id: OTP-10851
As of ERTS-5.10/OTP-R16A node names passed in the EPMD protocol are required to be encoded in UTF-8. Since EPMD previously accepted latin1 encoded node names this is an incompatibility. However, since Erlang nodes always have required characters in node names to be 7-bit ASCII characters (and still do require this), this incompatibility should not effect anyone using EPMD as an Erlang Port Mapper Daemon.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-10872 Aux Id: OTP-10753
The +pc flag to erl can be used to set the range of characters considered printable. This affects how the shell and io:format("~tp",...) functionality does heuristic string detection. More can be read in STDLIB users guide.
Own Id: OTP-10884
Fix a number of type cast errors related to formatted printing on Win64 that can potentially cause problem when the Erlang VM exceeds 4 GB of ram. (Thanks to Blaine Whittle for the original patch)
Own Id: OTP-10887
The effect of the deprecated environment variable ERL_MAX_PORTS had been removed prematurely. It has now been re-added. Note that this is still scheduled to be released in R17B.
Own Id: OTP-10895

Erts 5.10

Fixed Bugs and Malfunctions

Set new peeled off SCTP socket to nonblocking socket (Thanks to Jonas Falkevik)
Own Id: OTP-10491
Fix various typos (thanks to Tuncer Ayaz)
Own Id: OTP-10611
Fix fd leak when using async thread pool
When using the async thread pool, if an erlang process asks to open a file and it gets shutdown/killed while the file:open/2 call hasn't returned, it's possible to leak a file descriptor against the target file. This has now been fixed. (Thanks to Filipe David Manana)
Own Id: OTP-10677
Use sys/types.h instead of string.h to pull ssize_t definition to erl_driver.h. This fixes build issue on NetBSD. (Thanks to Yamamoto Takashi).
Own Id: OTP-10699
Arguments given with the -run or -s flags to erl are now translated according to the file name encoding mode of the runtime system.
Own Id: OTP-10702
The octet counters in the gen_tcp/inet interface could behave in unexpected ways on 64bit platforms. The behaviour is now as expected.
Own Id: OTP-10746
Certain linux kernels, most notably in redhat and CentOS distribution, had a bug in writev which generated an infinite loop in the tcp code of the VM. The bug is now worked around.
Own Id: OTP-10747
A process that got killed (got an exit signal) while operating on a compresseed file, could cause a segmentation fault in the VM. This is now corrected. Thanks to Filipe David Manana for identifying the problem and submitting a solution.
Own Id: OTP-10748
Windows previously used three digit exponent in formatting which caused difference between platforms, as can be seen by float_to_list/1. This has now been fixed.
Own Id: OTP-10751

Improvements and New Features

A boolean socket option 'ipv6_v6only' for IPv6 sockets has been added. The default value of the option is OS dependent, so applications aiming to be portable should consider using {ipv6_v6only,true} when creating an inet6 listening/destination socket, and if necessary also create an inet socket on the same port for IPv4 traffic. See the documentation.
Own Id: OTP-8928 Aux Id: kunagi-193 [104]
It is now allowed to define stubs for BIFs, to allow type specs to be written for BIFs. For example, if there is BIF called lists:member/2, a dummy definition of lists:member/2 is now allowed.
Own Id: OTP-9861
Process optimizations. The most notable:
- New internal process table implementation allowing for both parallel reads as well as writes. Especially read operations have become really cheap. This reduce contention in various situations. For example when, spawning processes, terminating processes, sending messages, etc.
- Optimizations of run queue management reducing contention.
- Optimizations of process internal state changes reducing contention.
These changes imply changes of the characteristics the system. Most notable: changed timing in the system.
Own Id: OTP-9892 Aux Id: OTP-10167
Non-blocking code loading. Earlier when an Erlang module was loaded, all other execution in the VM were halted while the load operation was carried out in single threaded mode. Now modules are loaded without blocking the VM. Processes may continue executing undisturbed in parallel during the entire load operation. The load operation is completed by making the loaded code visible to all processes in a consistent way with one single atomic instruction. Non-blocking code loading will improve realtime characteristics when modules are loaded/upgraded on a running SMP system.
Own Id: OTP-9974
In the SMP emulator, turning on and off tracing will no longer take down the system to single-scheduling.
Own Id: OTP-10122
Remove VxWorks support
Own Id: OTP-10146
Added a general framework for executing benchmarks of Erlang/OTP. Benchmarks for the Erlang VM and mnesia have been incorporated in the framework.
For details about how to add more benchmarks see $ERL_TOP/HOWTO/BENCHMARKS.md in the source distribution.
Own Id: OTP-10156
Optimized deletion of ETS-tables which significantly improves performance when large amounts of temporary tables are used.
This change imply changes of the characteristics the system. Most notable: changed timing in the system.
Own Id: OTP-10167 Aux Id: OTP-9892
Tuple funs (deprecated in R15B) are no longer supported.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-10170
New internal header scheme for allocators
Impact: Reduces size on object allocated in multiblock carriers by one word
Own Id: OTP-10273 Aux Id: kunagi-20 [20]
Major port improvements. The most notable:
- New internal port table implementation allowing for both parallel reads as well as writes. Especially read operations have become really cheap.This reduce contention in various situations. For example when, creating ports, terminating ports, etc.
- Dynamic allocation of port structures. This allow for a much larger maximum amount of ports allowed as a default. The previous default of 1024 has been raised to 65536. Maximum amount of ports can be set using the +Q command line flag of erl(1). The previously used environment variable ERL_MAX_PORTS has been deprecated and scheduled for removal in OTP-R17.
- Major rewrite of scheduling of port tasks. Major benefits of the rewrite are reduced contention on run queue locks, and reduced amount of memory allocation operations needed. The rewrite was also necessary in order to make it possible to schedule signals from processes to ports.
- Improved internal thread progress functionality for easy management of unmanaged threads. This improvement was necessary for the rewrite of the port task scheduling.
- Rewrite of all process to port signal implementations in order to make it possible to schedule those operations. All port operations can now be scheduled which allows for reduced lock contention on the port lock as well as truly asynchronous communication with ports.
- Optimized lookup of port handles from drivers.
- Optimized driver lookup when creating ports.
- Preemptible erlang:ports/0 BIF.
- Improving responsiveness by bumping reductions for a process calling a driver callback directly.
These changes imply changes of the characteristics of the system. The most notable:
- Order of signal delivery - The previous implementation of the VM has delivered signals from processes to ports in a synchronous stricter fashion than required by the language. As of ERTS version 5.10, signals are truly asynchronously delivered. The order of signal delivery still adheres to the requirements of the language, but only to the requirements. That is, some signal sequences that previously always were delivered in one specific order may now from time to time be delivered in different orders. This may cause Erlang programs that have made false assumptions about signal delivery order to fail even though they previously succeeded. For more information about signal ordering guarantees, see the chapter on communication in the ERTS user's guide. The +n command line flag of erl(1) can be helpful when trying to find signaling order bugs in Erlang code that have been exposed by these changes.
- Latency of signals sent from processes to ports - Signals from processes to ports where previously always delivered immediately. This kept latency for such communication to a minimum, but it could cause lock contention which was very expensive for the system as a whole. In order to keep this latency low also in the future, most signals from processes to ports are by default still delivered immediately as long as no conflicts occur. Such conflicts include not being able to acquire the port lock, but also include other conflicts. When a conflict occur, the signal will be scheduled for delivery at a later time. A scheduled signal delivery may cause a higher latency for this specific communication, but improves the overall performance of the system since it reduce lock contention between schedulers. The default behavior of only scheduling delivery of these signals on conflict can be changed by passing the +spp command line flag to erl(1). The behavior can also be changed on port basis using the parallelism option of the open_port/2 BIF.
- Execution time of the erlang:ports/0 BIF - Since erlang:ports/0 now can be preempted, the responsiveness of the system as a whole has been improved. A call to erlang:ports/0 may, however, take a much longer time to complete than before. How much longer time heavily depends on the system load.
- Reduction cost of calling driver callbacks - Calling a driver callback is quite costly. This was previously not reflected in reduction cost at all. Since the reduction cost now has increased, a process performing lots of direct driver calls will be scheduled out more frequently than before.
Potential incompatibilities:
- driver_send_term() has been deprecated and has been scheduled for removal in OTP-R17. Replace usage of driver_send_term() with usage of erl_drv_send_term().
- driver_output_term() has been deprecated and has been scheduled for removal in OTP-R17. Replace usage of driver_output_term() with usage of erl_drv_output_term().
- The new function erl_drv_busy_msgq_limits() has been added in order to able to control management of port queues.
The driver API version has been bumped to 2.1 from 2.0 due to the above changes in the driver API.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-10336 Aux Id: OTP-9892
The experimental support for packages has been removed.
Own Id: OTP-10348 Aux Id: kunagi-316 [227]
Wrong parameters when setting seq_trace-tokens from within a trace-pattern could crash the VM. This is now corrected.
Own Id: OTP-10522
Erlang specification 4.7.3 defines max tuple size to 65535 elements It is now enforced to no more than 16777215 elements (arity 24 bits)
Previous edge cases (28 bits) were not validated and could cause undefined behaviour.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-10633
Add insert_element/3 and delete_element/2
Own Id: OTP-10643
The previous default of a maximum of 32768 simultaneous processes has been raised to 262144. This value can be changed using the +P command line flag of erl(1). Note that the value passed now is considered as a hint, and that actual value chosen in most cases will be a power of two.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-10647 Aux Id: OTP-9892, OTP-10336
The previously (in R15) proposed scheduler wakeup strategy is now used by default. This strategy is not as quick to forget about previous overload as the previous strategy.
This change imply changes of the characteristics the system. Most notable: When a small overload comes and then disappears repeatedly, the system will for a bit longer time be willing to wake up schedulers than before. Timing in the system will due to this also change.
The previous strategy can still be enabled by passing the +sws legacy command line flag to erl.
Own Id: OTP-10661 Aux Id: OTP-10033
The +stbt command line argument of erl was added. This argument can be used for trying to set scheduler bind type. Upon failure unbound schedulers will be used.
Own Id: OTP-10668
Support ANSI in console
Unix platforms will no longer filter control sequences to the ttsl driver thus enabling ANSI and colors in console. (Thanks to Pedram Nimreezi)
Own Id: OTP-10678
Add file:allocate/3 operation
This operation allows pre-allocation of space for files. It succeeds only on systems that support such operation. (Thanks to Filipe David Manana)
Own Id: OTP-10680
Treat -Wreturn-type warnings as error when using GCC (Thanks to Tuncer Ayaz)
Own Id: OTP-10683
Implement ./otp_build configure --enable-silent-rules
With silent rules, the output of make is less verbose and compilation warnings are easier to spot. Silent rules are disabled by default and can be disabled or enabled at will by make V=0 and make V=1. (Thanks to Anthony Ramine)
Own Id: OTP-10726
Use share flags for all file operations on Windows. Thanks to Filipe David Borba Manana.
Own Id: OTP-10727
Make/fakefop adjustments. Thanks to Tuncer Ayaz and Sebastian Rasmussen.
Own Id: OTP-10733
The runtime system will now by default use 10 async threads if thread support has been enabled when building the runtime system.
This will prevent long blocking file-operations from blocking scheduler threads for long periods of time, which can be harmful. Apart from file-operations, it also effects other operations scheduled on the async thread pool by user implemented drivers.
The amount of async threads can be controlled by using the +A command line argument of erl. When running some offline tools you might want to disable async threads, but you are advised not to in the general case. Instead, you might want to increase the amount of async threads used.
This change imply changes of the characteristics the system compared to the previous default. The responsiveness of the system as a whole will be improved. Operations scheduled on the async thread pool will get an increased latency. The throughput of these operations may increase, or decrease depending on the type of the operations and how they get scheduled. In the case of file operations, the throughput very much depends on how the Erlang application access files. Multiple concurrent accesses to different files have the potential of an increased throughput.
Own Id: OTP-10736
The default reader group limit has been increased to 64 from 8. This limit can be set using the +rg command line argument of erl.
This change of default value will reduce lock contention on ETS tables using the read_concurrency option at the expense of memory consumption when the amount of schedulers and logical processors are between 8 and 64. For more information, see documentation of the +rg command line argument of erl.
Own Id: OTP-10737
New BIF float_to_list/2 which solves a problem of float_to_list/1 that doesn't allow specifying the number of digits after the decimal point when formatting floats (Thanks to Serge Aleynikov).
Own Id: OTP-10752
Limited support for unicode atoms in the external format and in the internal representation of the vm. This is a preparative feature in order to support communication with future releases of Erlang/OTP that may create unicode atoms.
Own Id: OTP-10753
Increased potential concurrency in ETS for write_concurrency option. The number of internal table locks has increased from 16 to 64. This makes it four times less likely that two concurrent processes writing to the same table would collide and thereby serialized. The cost is an increased constant memory footprint for tables using write_concurrency. The memory consumption per inserted record is not affected. The increased footprint can be particularly large if write_concurrency is combined with read_concurrency.
Own Id: OTP-10787

Erts 5.9.3.1

Known Bugs and Problems

Create an erl_crash.dump if no heart exists and no ERL_CRASH_DUMP_SECONDS is set (behaviour changed).
Don't create an erl_crash.dump if heart do exists and no ERL_CRASH_DUMP_SECONDS is set (behaviour not changed).
This changes the behaviour back to the R15B02 default considering if a beam was running with no heart.
Own Id: OTP-10602

Erts 5.9.3

Fixed Bugs and Malfunctions

Fix linking in OpenBSD. (Thanks to Matthew Dempsky)
Own Id: OTP-10395
Fix bug causing fallback atomics to be used even though healthy gcc atomics or libatomic_ops was detected.
Own Id: OTP-10418
Ensure 'erl_crash.dump' when asked for it. This will change erl_crash.dump behaviour.
* Not setting ERL_CRASH_DUMP_SECONDS will now terminate beam immediately on a crash without writing a crash dump file.
* Setting ERL_CRASH_DUMP_SECONDS to 0 will also terminate beam immediately on a crash without writing a crash dump file, i.e. same as not setting ERL_CRASH_DUMP_SECONDS environment variable.
* Setting ERL_CRASH_DUMP_SECONDS to a negative value will let the beam wait indefinitely on the crash dump file being written.
* Setting ERL_CRASH_DUMP_SECONDS to a positive value will let the beam wait that many seconds on the crash dump file being written.
A positive value will set an alarm/timeout for restart both in beam and in heart if heart is running.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-10422 Aux Id: kunagi-250 [161]
Fix bug where MSVRT100.dll was not included in the windows installer.
Own Id: OTP-10481
In the expression <<Bin/binary,...>>, if Bin was a bitstring with a size not a multiple of 8, either no exception was generated or an incorrect exception was generated. (Thanks to Adam Rutkowski for reporting this bug.)
Own Id: OTP-10524
The runtime system could crash while scheduling a port task. The port task was scheduled either due to an external I/O event being triggered, a driver timeout being triggered, or data being sent over a distribution channel.
Own Id: OTP-10556
erlang:memory(ets) erroneously included the size of each ETS-table main structure twice.
Own Id: OTP-10558
Fix compile error in generated file hipe_amd64_bifs.S for Solaris.
Own Id: OTP-10577
A faulty spec for process_info/2 could cause false dialyzer warnings. The spec is corrected.
Own Id: OTP-10584
In very rare cases, the VM could crash if a garbage collector was called while executing an appending bit syntax instruction. The symptom was a core when reallocating memory in the function erts_bs_append. The garbage collector bug is now corrected.
Own Id: OTP-10590

Improvements and New Features

Improve support for building and testing in embedded ppc environments.
Own Id: OTP-10265 Aux Id: kunagi-159 [daf97f67-5724-4812-a5b6-7e86990133d2-1]
Due to a race condition on Windows, sometimes when printing to standard output and then immediately terminating erlang all data would not be printed. The emulator now waits for all data to be printed before exiting.
Own Id: OTP-10325 Aux Id: kunagi-166 [dd72d0e2-3e76-4a51-8b56-7564e24eecae]
The frequency with which sleeping schedulers are woken due to outstanding memory deallocation jobs has been reduced.
Own Id: OTP-10476 Aux Id: OTP-10162
Clearer warnings about the dangers of misuse of native functions and drivers have been added to the documentation.
Own Id: OTP-10557

Erts 5.9.2

Fixed Bugs and Malfunctions

Fix erl_prim_loader errors in handling of primary archive. The following errors have been corrected:
- If primary archive was named "xxx", then a file in the same directory named "xxxyyy" would be interpreted as a file named "yyy" inside the archive.
- erl_prim_loader did not correctly create and normalize absolute paths for primary archive and files inside it, so unless given with exact same path files inside the archive would not be found. E.g. if escript was started as /full/path/to/xxx then "./xxx/file" would not be found since erl_prim_loader would try to match /full/path/to/xxx with /full/path/to/./xxx. Same problem with ../.
- Depending on how the primary archive was built, erl_prim_loader:list_dir/1 would sometimes return an empty string inside the file list. This was a virtual element representing the top directory of the archive. This has been removed.
Thanks to Tuncer Ayaz and Shunichi Shinohara for reporting and co-authoring corrections.
Own Id: OTP-10071
Fix: Add port-I/O statistics for active once and true and not only active false.
Own Id: OTP-10073
The 64-bit windows installer did not look in the right directories for 64-bit version of Microsoft Visual C++ 2010 Redistibutable Package and hence took the wrong decision about having to install the redistributable package if the 32-bit version was installed but not the 64-bit and vice versa. This bug has now been fixed Furthermore the sub-installer for the redistributable package is now run in silent mode if the erlang installer is.
Own Id: OTP-10096
epmd would fail to start automatically when starting a distributed erlang node installed in a location with a whitespace in the path.
Own Id: OTP-10106
A more or less harmless bug that sometimes caused memory deallocations to be delayed longer than intended has been fixed.
Own Id: OTP-10116
Fix bug causing emulator crash when running HiPE on ARM. Bug has existed since R15B.
Own Id: OTP-10137
A bug regarding spaces in C function prototypes has been fixed. (Thanks to Richard O'Keefe.)
Own Id: OTP-10138
Corrected dtrace pid length in message related probes. (Thanks to Zheng Siyao)
Own Id: OTP-10142
Correct formatting in exit error messages
Ensure displayed sizes are not negative. (Thanks to Michael Santos)
Own Id: OTP-10148
fix escript/primary archive reloading
If the mtime of an escript/primary archive file changes after being added to the code path, correctly reload the archive and update the cache. (Thanks to Tuncer Ayaz)
Own Id: OTP-10151
Doc fix: link from erlang:now/0 to os:timestamp/0
Sometimes os:timestamp/0 is more appropriate than erlang:now/0. The documentation for the former has a link to the latter; this patch adds a link in the other direction to make os:timestamp/0 more visible. Thanks to Magnus Henoch
Own Id: OTP-10180
The caret in the werl window (on Windows) could appear at the wrong place after regaining focus. This is now corrected.
Own Id: OTP-10181
Fix bug that in some cases could cause corrupted binaries in ETS tables with compressed option.
Own Id: OTP-10182
Fix use of "clever" mktime
Commit 1eef765 introduced regression (conditional _always_ evaluates to true) in which erlang:localtime_to_universaltime/2 stopped working on systems configured with timezone without DST (i.e. UTC) on *BSD platforms: 1> erlang:localtime_to_universaltime({{2012,1,1},{0,0,0}}, true). ** exception error: bad argument Thanks to Piotr Sikora
Own Id: OTP-10187
Relocate bodies of DTrace probes to the statically-linked VM.
Due to various operating systems (in both the DTrace and SystemTap worlds) not fully supporting DTrace probes (or SystemTap-compatibility mode probes) in shared libraries, we relocate those probes to the statically-linked virtual machine. This could be seen as pollution of the pristine VM by a (yet) experimental feature. However:
1. This code can be eliminated completely by the C preprocessor. 2. Leaving the probes in the dyntrace NIF shared library simply does not work correctly on too many platforms. Many thanks to Macneil Shonle at Basho for assisting when my RSI-injured fingers gave out. (note: Solaris 10 and FreeBSD 9.0-RELEASE can take a long time to compile)
Own Id: OTP-10189
Fix bug in ets:test_ms/2 that could cause emulator crash when using '$_' in match spec.
Own Id: OTP-10190
Supplying a filename longer than the operating system MAX_PATH to file:read_link/1 would cause a crash (Segemntation fault/Critical Error) on all platforms. This is now corrected.
Own Id: OTP-10200
If Perl was configured to interpret files as being encoded in UTF-8, the build would crash in make_preload. (Thanks to Aaron Harnly for noticing this issue.)
Own Id: OTP-10201
Fix the erlc -MP flag
Because of a copy-and-paste error in erlc.c, the -MP flag had the same effect as -MG. As a workaround, you had to pass +makedep_phony to enable the MP option. This patch makes -MP work as intended.
Own Id: OTP-10211
Allow mixed IPv4 and IPv6 addresses to sctp_bindx
Also allow mixed address families to bind, since the first address on a multihomed sctp socket must be bound with bind, while the rest are to be bound using sctp_bindx. At least Linux supports adding address of mixing families. Make inet_set_faddress function available also when HAVE_SCTP is not defined, since we use it to find an address for bind to be able to mix ipv4 and ipv6 addresses. Thanks to Tomas Abrahamsson
Own Id: OTP-10217
Fix support for leap seconds-aware timezones
erlang:universaltime_to_localtime is leap seconds-aware (since 2008), however erlang:localtime_to_universaltime is not, which gives surprising results on systems configured with leap seconds-aware timezones: 1> erlang:universaltime_to_localtime({{2012,1,1},{0,0,0}}). {{2012,1,1},{0,0,0}} 2> erlang:localtime_to_universaltime({{2012,1,1},{0,0,0}}). {{2012,1,1},{0,0,24}} and completely breaks calendar:local_time_to_universal_time_dst: 3> calendar:local_time_to_universal_time_dst({{2011,1,1},{0,0,0}}). [] Thanks to Piotr Sikora
Own Id: OTP-10227
erlsrv: gracefully stop emulator on Windows shutdown
Windows will send the SERVICE_CONTROL_SHUTDOWN event to the service control handler when shutting down the system. Instead of ignoring the event, erlsrv will now invoke the stop action. Likewise, the Erlang emulator (and it's po drivers) must not quit upon reception of the CTRL_SHUTDOWN_EVENT event in th console control handler. Thanks to Jan Kloetzke
Own Id: OTP-10228
Fix dtrace bug in file rename operation.
Own Id: OTP-10234
Fix bug in memory management of driver port data locks (PDL). In some cases PDLs could be deallocated before ready_async or async_free callback was called.
Own Id: OTP-10249

Improvements and New Features

Add port and suspend options to lock-counter profiling. (Thanks to Rick Reed)
Own Id: OTP-10051
Latency when using the active_once option in gen_tcp communication is reduced.
Own Id: OTP-10055 Aux Id: sto139
Remove bit8 option support from inet
Own Id: OTP-10056
The OS Pid of a port program is now available by calling erlang:port_info(Port,os_pid), Thanks to Matthias Lang for the original patch.
Own Id: OTP-10057
Fix openpty usage in run_erl.
Reopening a slave file descriptor which was closed earlier could lead to a misbehaving connection. This has now been remedied.
Own Id: OTP-10076
Remove all code, documentation, options and diagnostic functions which were related to the experimental hybrid heap implementation.
Own Id: OTP-10105
Optimizations of memory deallocations.
Own Id: OTP-10162 Aux Id: OTP-7775
Optimization of process locking.
Own Id: OTP-10163
Added a xcomp example file for powerpc-dso-linux-gnu
Own Id: OTP-10198
Detect when middle endian doubles are used by a platform and account for it when decoding floats. (Thanks to Mike Sperber)
Own Id: OTP-10209

Erts 5.9.1.2

Fixed Bugs and Malfunctions

On Linux systems using heart (erl -heart) and a HEAR_BEAT_TIMEOUT less than default, heart could fire even though Erlang was running fine after approx 298 to 497 days (depending on kernel config). This was due to the behaviour of the times(2) system call. Usage of times(2) is now replaced with clock_gettime(2) and the CLOCK_MONOTONIC clock, resulting in a more stable solution. The Erlang VM itself has used clock_gettime(2) on linux since before R12B, so this only affects the heart program.
Own Id: OTP-10111 Aux Id: seq12075

Erts 5.9.1.1

Fixed Bugs and Malfunctions

If threads support for the runtime system had been disabled at compile time (--disable-threads had been passed to configure), and the +A command line argument of erl was passed when starting the runtime system, driver_system_info() erroneously claimed that the runtime system had async threads even though it had not.
Due to this bug the file driver did not split tasks into smaller chunks, but instead completed the whole task at once, i.e., the scheduler got occupied with I/O for a longer time than intended.
Own Id: OTP-10059

Improvements and New Features

A proposal for a new scheduler wakeup strategy has been implemented. For more information see the documentation of the +sws command line argument of erl.
Own Id: OTP-10033 Aux Id: Seq12025
A switch for configuration of busy wait length for scheduler threads has been added. For more information see the documentation of the +sbwt command line argument of erl.
Own Id: OTP-10044 Aux Id: Seq11976
The extra memory barriers introduced by bug-fix OTP-9281 were unnecessarily used also on tables without the write_concurrency option enabled. This could unnecessarily degrade performance of ETS tables without write_concurrency on some hardware (e.g. PowerPC) while not effecting performance at all on other hardware (e.g. x86/x86_64).
OTP-9281 (R14B03): ETS tables using the write_concurrency option could potentially get into an internally inconsistent state.
Own Id: OTP-10048 Aux Id: OTP-9281

Erts 5.9.1

Fixed Bugs and Malfunctions

erlang:system_profile erroneous profiled the profiler process when observing runnable processes. This has been corrected.
Own Id: OTP-9849
Calling trace_info/2 asking for information about a function that had native could crash the run-time system.
Own Id: OTP-9886
reduce smp locking time range in erts_garbage_collect (thanks to Jovi Zhang)
Own Id: OTP-9912
Fix typo in supervisor behaviour doc (Thanks to Ricardo Catalinas Jiménez)
Own Id: OTP-9924
Correct spelling of registered (Thanks to Richard Carlsson)
Own Id: OTP-9925
erts: Remove unused variable (Thanks to Jovi Zhang)
Own Id: OTP-9926
Fix bug in ETS with compressed option and insertion of term containing large integers (>2G) on 64-bit machines. Seen to cause emulator crash. (Thanks to Diego Llarrull for excellent bug report)
Own Id: OTP-9932
Handle Linux OS where /sys/devices/system/node is only readable by root. Fallback to /sys/devices/system/cpu for topology info.
Own Id: OTP-9978
When an escript ends now all printout to standard output and standard error gets out on the terminal. This bug has been corrected by changing the behaviour of erlang:halt/0,1, which should fix the same problem for other escript-like applications, i.e that data stored in the output port driver buffers got lost when printing on a TTY and exiting through erlang:halt/0,1.
The BIF:s erlang:halt/0,1 has gotten improved semantics and there is a new BIF erlang:halt/2 to accomplish something like the old semantics. See the documentation.
Now erlang:halt/0 and erlang:halt/1 with an integer argument will close all ports and allow all pending async threads operations to finish before exiting the emulator. Previously erlang:halt/0 and erlang:halt(0) would just wait for pending async threads operations but not close ports. And erlang:halt/1 with a non-zero integer argument would not even wait for pending async threads operations.
To roughly the old behaviour, to not wait for ports and async threads operations when you exit the emulator, you use erlang:halt/2 with an integer first argument and an option list containing {flush,false} as the second argument. Note that now is flushing not dependent of the exit code, and you cannot only flush async threads operations which we deemed as a strange behaviour anyway.
Also, erlang:halt/1,2 has gotten a new feature: If the first argument is the atom 'abort' the emulator is aborted producing a core dump, if the operating system so allows.
Own Id: OTP-9985
Added check to inet driver to avoid building on operating systems that do not yet have IPv6 compatible socket API. (Thanks to Peer Stritzinger)
Own Id: OTP-9996
Fix bug when the number of CPUs actually found is lower than the configured value. (Thanks to Benjamin Herrenschmidt)
Own Id: OTP-10004
The runtime system without SMP support and without thread support erroneously busy waited when no work was present. This bug first appeared in erts-5.9.
Own Id: OTP-10019
Various typographical errors corrected in documentation for common_test, driver, erl_driver and windows installation instructions. (Thanks to Tuncer Ayaz)
Own Id: OTP-10037
Fix memory leak caused by race on exiting process
Own Id: OTP-10041

Improvements and New Features

Add erlang:statistics(scheduler_wall_time) to ensure correct determination of scheduler utilization. Measuring scheduler utilization is strongly preferred over CPU utilization, since CPU utilization gives very poor indications of actual scheduler/vm usage.
Own Id: OTP-9858
ERTS internal API improvements. In some cases the amount of atomic read operations needed have been reduced due to this.
Own Id: OTP-9922
The DTrace source patch from Scott Lystig Fritchie is integrated in the source tree. Using an emulator with dtrace probe is still not supported for production use, but may be a valuable debugging tool. Configure with --with-dynamic-trace=dtrace (or --with-dynamic-trace=systemtap) to create a build with dtrace probes enabled. See runtime_tools for documentation and examples.
Own Id: OTP-10017

Known Bugs and Problems

enif_make_copy may invalidate enif_inspect_binary.
Own Id: OTP-9828

Erts 5.9.0.1

Fixed Bugs and Malfunctions

A feature test for the lwsync instruction performed on PowerPC hardware at runtime system startup got into an eternal loop if the instruction was not supported. This bug was introduced in erts-5.9/OTP-R15B.
Own Id: OTP-9843
I/O events could potentially be delayed for ever when enabling kernel-poll on a non-SMP runtime system executing on Solaris. When also combined with async-threads the runtime system hung before completing the boot phase. This bug was introduced in erts-5.9/OTP-R15B.
Own Id: OTP-9844

Erts 5.9

Fixed Bugs and Malfunctions

Honor option packet_size for http packet parsing by both TCP socket and erlang:decode_packet. This gives the ability to accept HTTP headers larger than the default setting, but also avoid DoS attacks by accepting lines only up to whatever length you wish to allow. For consistency, packet type line also honor option packet_size. (Thanks to Steve Vinoski)
Own Id: OTP-9389
A few contracts in the lists module have been corrected.
Own Id: OTP-9616
The Unicode noncharacter code points 16#FFFE and 16#FFFE were not allowed to be encoded or decoded using the unicode module or bit syntax. That was inconsistent with the other noncharacters 16#FDD0 to 16#FDEF that could be encoded/decoded. To resolve the inconsistency, 16#FFFE and 16#FFFE can now be encoded and decoded. (Thanks to Alisdair Sullivan.)
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-9624
Make epp search directory of current file first when including another file This completes a partial fix in R11 that only worked for include_lib(). (Thanks to Richard Carlsson)
Own Id: OTP-9645
Fixed memory leak in enif_inspect_io_list_as_binary when applied on a process independent environment.
Own Id: OTP-9668
The number of beam catches allowed in code are no longer statically defined and will grow according to its need.
Own Id: OTP-9692
Add missing parenthesis in heart doc.
Add missing spaces in the Reference Manual distributed section.
In the HTML version of the doc those spaces are necessary to separate those words.
Own Id: OTP-9693
Fixes module erlang doc style: option description (Thanks to Ricardo Catalinas Jiménez)
Own Id: OTP-9697
Specifying a scope to binary:match/3 when using multiple searchstrings resulted in faulty return values. This is now corrected.
Own Id: OTP-9701
The runtime system crashed if more than one thread tried to exit the runtime system at the same time.
Own Id: OTP-9705
Fix documentation for erlang:process_flag/2
For the subsection about process_flag(save_calls, N) there's an unrelated paragraph about process priorities which was copied from the preceding subsection regarding process_flag(priority, Level). (Thanks to Filipe David Manana)
Own Id: OTP-9714
Calls to erlang:system_flag(schedulers_online, N) and/or erlang:system_flag(multi_scheduling, block|unblock) could cause internal data used by this functionality to get into an inconsistent state. When this happened various problems occurred. This bug was quite hard to trigger, so hopefully no-one has been effected by it.
A spinlock used by the run-queue management sometimes got heavily contended. This code has now been rewritten, and the spinlock has been removed.
Own Id: OTP-9727
Use libdlpi to get physical address (Thanks to Trond Norbye)
Own Id: OTP-9818

Improvements and New Features

An option list argument can now be passed to file:read_file_info/2, file:read_link_info/2 and file:write_file_info/3 and set time type information in the call. Valid options are {time, local}, {time, universal} and {time, posix}. In the case of posix time no conversions are made which makes the operation a bit faster.
Own Id: OTP-7687
A number of memory allocation optimizations have been implemented. Most optimizations reduce contention caused by synchronization between threads during allocation and deallocation of memory. Most notably:
- Synchronization of memory management in scheduler specific allocator instances has been rewritten to use lock-free synchronization.
- Synchronization of memory management in scheduler specific pre-allocators has been rewritten to use lock-free synchronization.
- The 'mseg_alloc' memory segment allocator now use scheduler specific instances instead of one instance. Apart from reducing contention this also ensures that memory allocators always create memory segments on the local NUMA node on a NUMA system.
Own Id: OTP-7775
The ethread atomic memory operations API used by the runtime system has been extended and improved.
The ethread library now also performs runtime tests for presence of hardware features, such as for example SSE2 instructions, instead of requiring this to be determined at compile time.
All uses of the old deprecated atomic API in the runtime system have been replaced with the use of the new atomic API. In a lot of places this change imply a relaxation of memory barriers used.
Own Id: OTP-9014
gen_sctp:open/0-2 may now return {error,eprotonosupport} if SCTP is not supported
gen_sctp:peeloff/1 has been implemented and creates a one-to-one socket which also are supported now
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-9239
Sendfile has been added to the file module's API. sendfile/2 is used to read data from a file and send it to a tcp socket using a zero copying mechanism if available on that OS.
Thanks to Tuncer Ayaz and Steve Vinovski for original implementation
Own Id: OTP-9240
enif_get_reverse_list function added to nif API. This function should be used to reverse small lists which are deep within other structures making it impractical to do the reverse in Erlang.
Own Id: OTP-9392
The deprecated concat_binary/1 BIF has been removed. Use list_to_binary or iolist_to_binary/1 instead.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-9421
Erlang/OTP can now be built using parallel make if you limit the number of jobs, for instance using 'make -j6' or 'make -j10'. 'make -j' does not work at the moment because of some missing dependencies.
Own Id: OTP-9451
Line number and filename information are now included in exception backtraces as a fourth element in the MFA tuple. The information will be pretty-printed by the shell and used by common_test to provide better indication of where a test case.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-9468
All binary constants used to be handled as heap binaries (i.e. the entire binary would be copied when sent to another process). Binary constants larger than 64 bytes are now refc binaries (i.e. the actual data in the binary will not be copied when sent to another process).
Own Id: OTP-9486
If a float and an integer is compared, the integer is only converted to a float if the float datatype can contain it. Otherwise the float is converted to an integer.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-9497
Add NIF function enif_is_number
This function allows for easily determining if a term represents or not a number (integer, float, small or big).(Thanks to Filipe David Manana)
Own Id: OTP-9629
The ERTS internal system block functionality has been replaced by new functionality for blocking the system. The old system block functionality had contention issues and complexity issues. The new functionality piggy-backs on thread progress tracking functionality needed by newly introduced lock-free synchronization in the runtime system. When the functionality for blocking the system isn't used, there is more or less no overhead at all. This since the functionality for tracking thread progress is there and needed anyway.
Own Id: OTP-9631
An ERTS internal, generic, many to one, lock-free queue for communication between threads has been introduced. The many to one scenario is very common in ERTS, so it can be used in a lot of places in the future. Currently it is used by scheduling of certain jobs, and the async thread pool, but more uses are planned for the future.
Drivers using the driver_async functionality are not automatically locked to the system anymore, and can be unloaded as any dynamically linked in driver.
Scheduling of ready async jobs is now also interleaved in between other jobs. Previously all ready async jobs were performed at once.
Own Id: OTP-9632
Tuple funs (a two-element tuple with a module name and a function) are now officially deprecated and will be removed in R16. Use 'fun M:F/A' instead. To make you aware that your system uses tuple funs, the very first time a tuple fun is applied, a warning will be sent to the error logger.
Own Id: OTP-9649
Changed the internal BIF calling convention. Will make simpler faster code and allow BIFs with an arbitrary arity.
Own Id: OTP-9662
Windows native critical sections are now used internally in the runtime system on Windows as mutex implementation. This since they perform better under extreme contention than our own implementation.
Own Id: OTP-9671
Convert some erl_nif macros into inline functions. Allow for better compile time type checking. (Thanks to Tuncer Ayaz)
Own Id: OTP-9675
The +scl command line flag has been added. It can be used for disabling compaction of scheduler load. For more information see the erl documentation.
Own Id: OTP-9695
The build system has been updated so that Erlang/OTP can be built on Mac OS X Lion systems without a GCC compiler. The INSTALL guide has been updated with instructions on how to install a GCC compiler and build Erlang/OTP with it, in order to get a run-time system with better performance.
Own Id: OTP-9712
When loading a module, the system use to run on a single scheduler during the entire loading process. This has been changed to only take down the system just before inserting the loaded code into the system tables, resulting in a much shorter disruption if a module is loaded in a busy system. (Suggested by Bob Ippolito.)
Own Id: OTP-9720
Possible to run HiPE without floating point exceptions (FPE). Useful on platforms that lack reliable FPE. Slower float operations compared to HiPE with FPE.
Own Id: OTP-9724
As of ERTS version 5.9 (OTP-R15B) the runtime system will by default not bind schedulers to logical processors.
If the Erlang runtime system is the only operating system process that binds threads to logical processors, this improves the performance of the runtime system. However, if other operating system processes (as for example another Erlang runtime system) also bind threads to logical processors, there might be a performance penalty instead. In some cases this performance penalty might be severe. Due to this, we change the default so that the user must make an active decision in order to bind schedulers.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-9726
The use of erlang:system_flag(scheduler_bind_type, _) and erlang:system_flag(cpu_topology, _) have been deprecated and scheduled for removal in erts-5.10/OTP-R16. For more information see the documentation of erlang:system_flag/2.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-9749
An ancient workaround for a Windows bug was removed from the open_port code, open_port({spawn,...}...) is now faster. Thanks to Daniel Goertzen.
Own Id: OTP-9766
The use of deprecated 32bit time_t on 32bit Windows is removed.
Own Id: OTP-9767
The NIF reload mechanism is deprecated. Do not use it as an upgrade method for live production systems. It might be removed in future releases. It can still serve as a development feature but a warning message will be logged each time it is used.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-9771
The driver interface has been changed to enable 64-bit aware drivers. Most importantly the return types for ErlDrvEntry callbacks 'call' and 'control' has ben enlarged which require drivers to be changed or they will cause emulator crashes. See Rewrites for 64-bit driver interface in the driver manual.
Due to this driver version management is now mandatory. A driver that is not written with version management or a driver that was compiled with the wrong major version will be not be loaded by the emulator.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-9795
Eliminate use of deprecated regexp module
Own Id: OTP-9810

Erts 5.8.5

Fixed Bugs and Malfunctions

Several bugs concerning constant binary constructions such as <<0:4294967295>> have been corrected. Depending on the actual size of the binary and the type of run-time system (32-bit, halfword, 64-bit), such expression could either crash the run-time system or make the loader refuse loading of the module.
Own Id: OTP-9284
The Erlsrv utility failed to stop the erlang machine if no StopAction was defined when the service was stopped. This is now corrected.
Own Id: OTP-9344
Due to a bug in glibc the runtime system could abort while trying to destroy a mutex. A fix for this was introduced in R14B02. This fix did, however, not solve the problem. The runtime system will now issue a warning instead of aborting.
Own Id: OTP-9373 Aux Id: OTP-9009
Replace atom in DRV macro in prim_file with string
An experimental version of Dialyzer discovered that the atom that replaced the DRV macro in prim_file ends up in calls to erlang:open_port({spawn, Driver}, Portopts) as the Driver argument. The documentation states that this call requires a string there.
This change is also consistent with the one introduced in commit 0f03b1e9d2bef3bc830c31a369261af4c5234727 by Kostis Sagonas.
Own Id: OTP-9377
Fix typos in the epmd documentation (Thanks to Holger Weiß )
Own Id: OTP-9387
Fix faulty integer terms created by NIF API from 64-bit integers on halfword emulator. (Thanks to Paolo Negri and Paul Davis)
Own Id: OTP-9394
Fix epmd crash on vxworks caused by faulty argument to select() system call.
Own Id: OTP-9427 Aux Id: seq11855
The ets:test_ms function could in rare cases truncate the error messages. This is now corrected.
Own Id: OTP-9435
Fix bug related to hibernate and HiPE (clear F_HIBERNATE_SCHED flag)
F_HIBERNATE_SCHED flag that was introduced in b7ecdcd1ae9e11b8f75e must be cleared in hipe_mode_switch as well. Otherwise, processes running HiPE code that hibernate, wake up and then trap into a BIF will not be rescheduled.(Thanks to Paul Guyot)
Own Id: OTP-9452
Fix bug in FreeBSD topology detection code (Thanks to Paul Guyot)
Own Id: OTP-9453
Fix use of logical operator && with constant operand instead of bitwise & (Thanks to Cristian Greco)
Own Id: OTP-9454
inet: error if fd does not match socket domain
If an IPv4 fd is opened as an IPv6 socket, unexpected behaviour can occur. For example, if an IPv4 UDP socket is opened and passed into Erlang as an IPv6 socket, the first 3 bytes (corresponding to 1 byte representing the protocol family, 2 bytes set to the port) are stripped from the payload. The cause of the UDP payload truncation happens in inet_drv.c:packet_inet_input when a call to inet_get_address fails silently because the family is set to PF_INET6 but the buffer len is the size of an IPv4 struct sockaddr_in.
(Thanks to Andrew Tunnell-Jones for finding the bug and the test case!)
Own Id: OTP-9455
erts: use a union to avoid strict aliasing issues
Use a union for pointer type conversion to avoid compiler warnings about strict-aliasing violations with gcc-4.1. gcc >= 4.2 does not emit the warning. erts: adapt matrix_nif to R14 erl_nif API changes (Thanks To Tuncer Ayaz)
Own Id: OTP-9487
fix 64-bit issues in the garbage collection (Thanks to Richard Carlsson)
Own Id: OTP-9488
epmd: fix compiler warnings
Suppress compiler warnings about ignored return values. (Thanks to Michael Santos )
Own Id: OTP-9500
Fix non-existing function (erlang:disconnect/1) in distributed reference manual (Thanks to Fabian Król)
Own Id: OTP-9504
Document fdatasync -lrt requirement (SunOS <= 5.10) (Thanks to Tuncer Ayaz)
Own Id: OTP-9512
Let epmd ignore empty ERL_EPMD_ADDRESS
If the environment variable ERL_EPMD_ADDRESS is set to the empty string, empd now behaves like it does by default when ERL_EPMD_ADDRESS is unset. That is, in this case, epmd now listens on all available interfaces instead of using only the loopback interface, which happened because epmd added the loopback address to the (in this case empty) list of addresses specified via ERL_EPMD_ADDRESS.
Also, epmd now ignores ERL_EPMD_ADDRESS if it contains only separator characters (comma and space).
The same applies to epmd's -address option.(Thanks to Holger Weiß)
Own Id: OTP-9525
Remove dead code in erl_compile (Thanks to Tuncer Ayaz)
Own Id: OTP-9527
Add erlang:external_size/2 BIF
This BIF's second parameter is a list of options. Currently the only allowed option is {minor_version, Version} where version is either 0 (default) or 1. (Thanks to Filipe David Manana )
Own Id: OTP-9528
Fix enif_compare on 64bits machines
In 64bits machines the Sint type has a size of 8 bytes, while on 32bits machines it has a 4 bytes size. enif_compare was ignoring this and therefore returning incorrect values when the result of the CMP function (which returns a Sint value) doesn't fit in 4 bytes. (Thanks to Filipe David Manana)
Own Id: OTP-9533
Implement or fix -Werror option
If -Werror is enabled and there are warnings no output file is written. Also make sure that error/warning reporting is consistent. (Thanks to Tuncer Ayaz)
Own Id: OTP-9536
In some rare cases we did not have a run queue when scheduling misc ops. This is now fixed.
Own Id: OTP-9537
Remove misc. compiler warnings
Own Id: OTP-9542
Two bugs in gen_sctp has been corrected: getopts/setopts hence also send could only be called from socket owner, and options 'linger', 'rcvbuf' and 'sndbuf' was read from wrong protocol layer hence read wrong values by getopts.
Own Id: OTP-9544
Erlang/OTP can now be built on MacOS X Lion.
Own Id: OTP-9547
XML files have been corrected.
Own Id: OTP-9550 Aux Id: OTP-9541
Fix potential errors inspired by running cppcheck(1) (Thanks to Christian von Roques)
Own Id: OTP-9557
When auxiliary work was enqueued on a scheduler, the wakeup of the scheduler in order to handle this work could be lost. Wakeups in order to handle ordinary work were not effected by this bug. The bug only effected runtime systems with SMP support as follows:
- Deallocation of some ETS data structures could be delayed.
- On Linux systems not using the NPTL thread library (typically ancient systems with kernel versions prior to 2.6) and Windows systems, the {Port, {exit_status, Status}} message from a terminating port program could be delayed. That is, it only effected port programs which had been started by passing exit_status as an option to open_port/2.
Own Id: OTP-9567
Handle rare race in the crypto key server functionality
Own Id: OTP-9586

Improvements and New Features

Types and specifications have been added.
Own Id: OTP-9356
New allocator strategy "address order first fit". May ease the emptying of memory carriers and thereby real release of memory back to the OS.
Own Id: OTP-9424
The new erlang:check_old_code/1 BIF checks whether a module has old code.
Own Id: OTP-9495
Update documentation and specifications of some of the zlib functions.
Own Id: OTP-9506
Detect the available CPUs on IRIX
Add support for querying the number of configured and online processors on SGI systems running IRIX.(Thanks to Holger Weiß)
Own Id: OTP-9531

Erts 5.8.4

Fixed Bugs and Malfunctions

Fix binary and iolist overflow problems. Typically problems arose in length calculation where the result would exceed (1 bsl 32 - 1).
Own Id: OTP-9118
Using the old erlang shell (i.e. erl instead on werl) on windows and doing several init:restart's would eventually hang the VM. That is no longer the case.
Own Id: OTP-9139
Removed recursive C code when printing Erlang terms to buffers, avoiding stack overflows that could cause VM to crash.
Own Id: OTP-9140
The send_timeout option in gen_tcp did not work properly in active mode or with {active,once} options. This is now corrected.
Own Id: OTP-9145
Fixed various typos across the documentation (Thanks to Tuncer Ayaz)
Own Id: OTP-9154
Remove duplicate stack entries which could occur after calling certain BIFs.
Own Id: OTP-9163
A race when starting two nodes simultaneously using run_erl has been removed.
Own Id: OTP-9164
Add documentation on .erlang processing back again (Thanks to Gabor Liptak)
Own Id: OTP-9189
Remove gratuitous paren in driver_entry(Thanks to Tuncer Ayaz)
Own Id: OTP-9192
Fix some wrong pointer dereferences (Thanks to Cristian Greco)
Own Id: OTP-9194
erts: Remove unused variables (Thanks to Tuncer Ayaz)
Own Id: OTP-9205
The documentation for init:get_args/0 has been removed. init:get_args/0 itself was deprecated in R9C and removed in R12B. (Thanks to Eric Pailleau.)
Own Id: OTP-9209
Allow user to specify the IP address epmd binds to
The IP address(es) epmd binds to can now be specified by the user, either via epmd's new "-address" option or (if that's not used) by setting the environment variable ERL_EPMD_ADDRESS. Multiple addresses may be specified using a comma-separated list. If the loopback address is not in this list, it will be added implicitly, so that the daemon can be queried by an interactive epmd process.(Thanks to Holger Weiß)
Own Id: OTP-9213
epmd: include host address in local access check
In FreeBSD jails, the source and destination address of connections to localhost are changed to be the IP address of the jail. Consider connections from the host's IP address to itself (e.g., the source and destination address match) to be local for the access control checks. (Thanks to Michal Santos and Tom at diogunix.com)
Own Id: OTP-9214
Fix list returned by net_kernel:epmd_module
Function epmd_module of net_kernel returns a list instead of an atom, when the epmd_module-flag is used. (Thanks to Markus Knofe)
Own Id: OTP-9215
Fix epmd's dbg_perror() output
The dbg_perror() function now hands the current errno value over to dbg_gen_printf(). This fixes the problem that errno had been reset to zero by the time it was used (to print the corresponding error message) in the dbg_gen_printf() function. (Thanks to Holger Weiß)
Own Id: OTP-9223
heart: remove garbage appended to heart command
heart:get_cmd/0 is documented to return an empty string if the command is cleared. get_cmd/0 returns 2 extra bytes: 1 byte for the trailing null, 1 byte from the op (the op is an unsigned char and 2 bytes are allocated for it in the returned buffer). (Thanks to Michael Santos)
Own Id: OTP-9224
file: fix hang reading compressed files
The gzio driver goes into an infinite loop when reading past the end of a compressed file. Reported-By: Alex Morarash (Thanks to Michael Santos)
Own Id: OTP-9245
Eliminate alias warnings from gcc 4.5.2
Own Id: OTP-9250
Unsigned integer may overflow in error message (Thanks to Michael Santos)
Own Id: OTP-9251
Driver names should be strings, not atoms
Own Id: OTP-9253
driver_entry: Remove gratuitous paren and fix typo (Thanks to Tuncer Ayaz)
Own Id: OTP-9254
Fix format specifiers in erl_exit messages
Fix an error message by using an unsigned integer specifier as seen in a tweet by @metabrew: #erlang VM crashed with "no next heap size found: -2090496108, offset 0", suddenly allocated all available RAM
Also correct mis-typed string formats in bif.c.(Thanks to Michael Santos)
Own Id: OTP-9262
net_drv: remove unused tcp request id inet_drv: remove gratuitous assignment (Thanks to Tuncer Ayaz)
Own Id: OTP-9263
Teach run_erl RUN_ERL_DISABLE_FLOWCNTRL for disabling flow control
Flow control can cause unwanted behaviour of the beam process, if accidentally hit Ctrl-S (instead of Ctrl-D to detach) the entire beam may be blocked.
Fix this problem by making it possible to turn off flow control by setting the environment variable RUN_ERL_DISABLE_FLOWCNTRL. (Thanks to Jonas Faklkevik)
Own Id: OTP-9270
The following bugs due to missing memory barriers have been fixed:
- ETS tables using the write_concurrency option could potentially get into an internally inconsistent state.
- ETS tables using the ordered_set option could potentially get into an internally inconsistent state.
- A number of memory barriers have been added when building with the libatomic_ops API (i.e. when passing --with-libatomic_ops=PATH to configure) and the tilera atomics API (i.e. when building for the tilera chip). Note that these bugs were due to erroneous usage of the APIs, and not in the implementations of the APIs. When using these APIs the following bugs where present:
  - The BIF erlang:ports/0 could return an erroneous result.
  - A thread blocking other threads during code loading, or setup of tracing could potentially read invalid data.
  - Fixation of ETS tables could potentially get into an internally inconsistent state.
Own Id: OTP-9281
Fix halfword bug for ETS ordered_set when doing select/match with partly bound key.
Own Id: OTP-9292
Fix bug in code:is_module_native that caused crash for deleted modules.
Own Id: OTP-9298
Calling driver_async_cancel() could cause a scheduler thread to enter an eternal loop doing no useful work. (Thanks to Anders Ramsell)
Own Id: OTP-9302

Improvements and New Features

New enif_is_exception function to allow NIFs to determine whether an ERL_NIF_TERM represents an exception. (Thanks to Steve Vinoski)
Own Id: OTP-9150
A process being garbage collected by another process could be scheduled on another scheduler. This prevented this scheduler from doing any useful work until the garbage collection was done. This either occurred due to a explicit call to the garbage_collect/1 BIF, or due to a garbage collection part of code loading. A process being garbage collected like this will now not be scheduled until the garbage collection has completed.
Own Id: OTP-9211
Remove unnecessary validation copy in prim_file:drv_command/3 (Thanks to Tony Rogvall)
Own Id: OTP-9276
Symbolic link handling on windows have been slightly updated to map error conditions more consequently and correctly read directory links created outside of the Erlang environment.
Own Id: OTP-9279
Due to standard library DLL mismatches between versions of OpenSSL and Erlang/OTP, OpenSSL is now linked statically to the crypto driver on Windows. This fixes problems starting crypto when running Erlang as a service on all Windows versions.
Own Id: OTP-9280
Halfword emulator memory handling improvements:
- Much more of internal memory structures have been made able to use "high" memory and are no longer restricted to the 4Gb limit that still applies for all process heap data.
- Fixed faulty values from erlang:memory() caused by 32-bit counter overflow.
- New counter low in erlang:memory() that sums up all memory restricted by 4Gb limit.
Own Id: OTP-9291 Aux Id: seq11841
The value set in the undocumented and unsupported ERL_version_FLAGS (e.g. ERL_R14B03_FLAGS) environment variable can now be overridden by the command line (similar to ERL_AFLAGS).
Own Id: OTP-9297

Erts 5.8.3.2

Known Bugs and Problems

Fix halfword emulator bug in ets:select_delete for ordered_set that caused emulator to crash.
Own Id: OTP-9258 Aux Id: seq11836

Erts 5.8.3.1

Fixed Bugs and Malfunctions

Ets table type ordered_set could order large integer keys wrongly on pure 64bit platforms. This is now corrected.
Own Id: OTP-9181
The status of a process was unnecessarily set to waiting before a process was enqueued in a run queue. This bug was harmless up until OTP-R14B01. In OTP-R14B02 erlang:hibernate/3 was fixed (OTP-9125). After the introduction of OTP-9125, the previously harmless process status bug sometimes caused erroneous badarg exceptions from process_info().
OTP-9125 also introduced a thread unsafe access to the status field of a process which now also have been fixed.
* INCOMPATIBILITY with noxs *
Own Id: OTP-9197

Erts 5.8.3

Fixed Bugs and Malfunctions

The scroll wheel now scrolls the werl window on Windows.
Own Id: OTP-8985
Some malformed distribution messages could cause VM to crash, this is now corrected.
Own Id: OTP-8993
The OS function getifaddrs() can return NULL in some address fields for e.g PPP and tunnel devices which caused the emulator to segfault. This bug has now been corrected.
Own Id: OTP-8996
The expression <<A:0>> would always produce an empty binary, even if A was not an integer. Corrected to cause a badarg exception if the type of A is invalid. (Thanks to Zvi.)
Own Id: OTP-8997
A bug that potentially could cause an emulator crash when deleting an ETS-table has been fixed. A resource leak when hitting the maximum amount of ETS-tables allowed has also been fixed.
Own Id: OTP-8999
A bug in the exit/2 BIF could potentially cause an emulator crash.
Own Id: OTP-9005
Due to a bug in glibc the runtime system could abort while trying to destroy a mutex. The runtime system will now issue a warning instead of aborting.
Own Id: OTP-9009
A bug in epmd could create strange behaviour when listen() calls failed. This is now corrected thanks to Steve Vinoski.
Own Id: OTP-9024
When setting file_info the win32_driver will now correctly set access and modified time. Previously these entities were swapped.
Own Id: OTP-9046
Setting scheduler bind type to unbound failed if binding of schedulers wasn't supported, or if CPU topology wasn't present. This even though the documentation stated that it is possible to set the bind type to unbound.
Own Id: OTP-9056 Aux Id: Seq11779
Two problems were fixed in crash dump: The time left for timers are now shown as unsigned integers and the contents of ordered_set ETS tables is no longer included.
Own Id: OTP-9057
The VM could fail to set IP_TOS and SO_PRIORITY in certain situations, either because sockets were supplied as open file descriptors, or because SO_PRIORITY by default was set higher than the user can explicitly set it to. Those situations are now handled.
Own Id: OTP-9069
Wx on MacOS X generated complains on stderr about certain cocoa functions not being called from the "Main thread". This is now corrected.
Own Id: OTP-9081
Fix a couple typos in driver_entry(3) (thanks to Tuncer Ayaz).
Own Id: OTP-9085
Mention that "-detached" implies "-noinput"
Clarify that specifying "-noinput" is unnecessary if the "-detached" flag is given. (thanks to Holger Weiß)
Own Id: OTP-9086
A potential problem (found by code inspection) when calling a fun whose code was not loaded has been fixed.
Own Id: OTP-9095
The emulator could get into a state where it didn't check for I/O.
Own Id: OTP-9105 Aux Id: Seq11798
Attempting to create binaries exceeding 2Gb (using for example term_to_binary/1) would crash the emulator with an attempt to allocate huge amounts of memory. (Thanks to Jon Meredith.)
Own Id: OTP-9117
Fix erlang:hibernate/3 on HiPE enabled emulator (Thanks to Paul Guyot)
Own Id: OTP-9125

Improvements and New Features

From this release, the previously experimental halfword emulator is now official. It can be enabled by giving the --enable-halfword-emulator option to the configure script.
The halfword emulator is a 64-bit application, but uses halfwords (32-bit words) for all data in Erlang processes, therefore using less memory and being faster than the standard 64-bit emulator. The total size of all BEAM code and all process data for all processes is limited to 4Gb, but ETS tables and off-heap binaries are only limited by the amount of available memory.
Own Id: OTP-8941
32-bit atomic memory operations have been introduced internally in the run time system, and are now used where appropriate. There were previously only atomic memory operations of word size available. The 32-bit atomic memory operations slightly reduce memory consumption, and slightly improve performance on 64-bit runtime systems.
Own Id: OTP-8974
Performance enhancements for looking up timer-entries and removing timers from the wheel.
Own Id: OTP-8990
Write accesses to ETS tables have been optimized by reducing the amount of atomic memory operations needed during a write access.
Own Id: OTP-9000
Strange C coding in the VM made the -D_FORTIFY_SOURCE option to gcc-4.5 react badly. The code is now cleaned up so that it's accepted by gcc-4.5.
Own Id: OTP-9025
The memory footprint for loaded code has been somewhat reduced (especially in the 64-bit BEAM machine).
Own Id: OTP-9030
The maximum number of allowed arguments for an Erlang function has been lowered from 256 to 255, so that the number of arguments can now fit in a byte.
Own Id: OTP-9049
Dependency generation for Makefiles has been added to the compiler and erlc. See the manual pages for compile and erlc. (Thanks to Jean-Sebastien Pedron.)
Own Id: OTP-9065

Erts 5.8.2

Fixed Bugs and Malfunctions

Fix format_man_pages so it handles all man sections and remove warnings/errors in various man pages.
Own Id: OTP-8600
The configure command line argument --enable-ethread-pre-pentium4-compatibility had no effect. This option is now also automatically enabled if required on the build machine.
Own Id: OTP-8847
Windows 2003 and Windows XP pre SP3 would sometimes not start the Erlang R14B VM at all due to a bug in the cpu topology detection. The bug affects Windows only, no other platform is even remotely affected. The bug is now corrected.
Own Id: OTP-8876
The HiPE run-time in the 64-bit emulator could do a 64-bit write to a 32-bit struct field. It happened to be harmless on Intel/AMD processors. Corrected. (Thanks to Mikael Pettersson.)
Own Id: OTP-8877
A bug in erl_drv_tsd_get() and enif_tsd_get() could cause an emulator crash. These functions are currently not used in OTP. That is, the crash only occur on systems with user implemented NIF libraries, or drivers that use one of these functions.
Own Id: OTP-8889
Calling erlang:system_info({cpu_topology, CpuTopologyType}) with another CpuTopologyType element than one of the documented atoms defined, detected, or used caused an emulator crash. (Thanks to Paul Guyot)
Own Id: OTP-8914
The ERTS internal rwlock implementation could get into an inconsistent state. This bug was very seldom triggered, but could be during heavy contention. The bug was introduced in R14B (erts-5.8.1).
The bug was most likely to be triggered when using the read_concurrency option on an ETS table that was frequently accessed from multiple processes doing lots of writes and reads. That is, in a situation where you typically don't want to use the read_concurrency option in the first place.
Own Id: OTP-8925 Aux Id: OTP-8544
Tracing to port could cause an emulator crash when unloading the trace driver.
Own Id: OTP-8932
Removed use of CancelIoEx on Windows that had been shown to cause problems with some drivers.
Own Id: OTP-8937
The fallback implementation used when no native atomic implementation was found did not compile. (Thanks to Patrick Baggett, and Tuncer Ayaz)
Own Id: OTP-8944
Some integer values used during load balancing could under rare circumstances wrap causing a load unbalance between schedulers.
Own Id: OTP-8950
The windows VM now correctly handles appending to large files (> 4GB).
Own Id: OTP-8958
Name resolving of IPv6 addresses has been implemented for Windows versions that support it. The use of ancient resolver flags (AI_V4MAPPED | AI_ADDRCONFIG) to the getaddrinfo() function has been removed since e.g FreeBSD regard mapped IPv4 addresses to be a security problem and the semantics of the address configured flag is uncertain.
Own Id: OTP-8969

Improvements and New Features

The help texts produced by the configure scripts in the top directory and in the erts directory have been aligned and cleaned up.
Own Id: OTP-8859
When the runtime system had fewer schedulers than logical processors, the system could get an unnecessarily large amount reader groups.
Own Id: OTP-8861
run_rel has been updated to support Solaris's /dev/ptmx device and to load the necessary STREAMS modules so that to_erl can provide terminal echo of keyboard input. (Thanks to Ryan Tilder.)
Own Id: OTP-8878
The Erlang VM now supports Unicode filenames. The feature is turned on by default on systems where Unicode filenames are mandatory (Windows and MacOSX), but can be enabled on other systems with the '+fnu' emulator option. Enabling the Unicode filename feature on systems where it is not default is however considered experimental and not to be used for production. Together with the Unicode file name support, the concept of "raw filenames" is introduced, which means filenames provided without implicit unicode encoding translation. Raw filenames are provided as binaries, not lists. For further information, see stdlib users guide and the chapter about using Unicode in Erlang. Also see the file module manual page.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-8887
Buffer overflows have been prevented in erlc, dialyzer, typer, run_test, heart, escript, and erlexec.
(Thanks to Michael Santos.)
Own Id: OTP-8892
The runtime system is now less eager to suspend processes sending messages over the distribution. The default value of the distribution buffer busy limit has also been increased from 128 KB to 1 MB. This in order to improve throughput.
Own Id: OTP-8901
The distribution buffer busy limit can now be configured at system startup. For more information see the documentation of the erl +zdbbl command line flag. (Thanks to Scott Lystig Fritchie)
Own Id: OTP-8912
The inet driver internal buffer stack implementation has been rewritten in order to reduce lock contention.
Own Id: OTP-8916
New ETS option compressed, to enable a more compact storage format at the expence of heavier table operations. For test and evaluation, erl +ec can be used to force compression on all ETS tables.
Own Id: OTP-8922 Aux Id: seq11658
There is now a new function inet:getifaddrs/0 modeled after C library function getifaddrs() on BSD and LInux that reports existing interfaces and their addresses on the host. This replaces the undocumented and unsupported inet:getiflist/0 and inet:ifget/2.
Own Id: OTP-8926
Support for detection of CPU topology and binding of schedulers on FreeBSD 8 have been added. (Thanks to Paul Guyot)
Own Id: OTP-8939
Several bugs related to hibernate/3 and HiPE have been corrected. (Thanks to Paul Guyot.)
Own Id: OTP-8952
Support for soft and hard links on Windows versions and filesystems that support them is added.
Own Id: OTP-8955
The win32 virtual machine is now linked large address aware. his allows the Erlang VM to use up to 3 gigs of address space on Windows instead of the default of 2 gigs.
Own Id: OTP-8956

Erts 5.8.1.2

Fixed Bugs and Malfunctions

Fix that the documentation top index generator can handle an Ericsson internal application group.
Own Id: OTP-8875
In embedded mode, on_load handlers that called code:priv_dir/1 or other functions in code would hang the system. Since the crypto application now contains an on_loader handler that calls code:priv_dir/1, including the crypto application in the boot file would prevent the system from starting.
Also extended the -init_debug option to print information about on_load handlers being run to facilitate debugging.
Own Id: OTP-8902 Aux Id: seq11703

Erts 5.8.1.1

Fixed Bugs and Malfunctions

Windows 2003 and Windows XP pre SP3 would sometimes not start the Erlang R14B VM at all due to a bug in the cpu topology detection. The bug affects Windows only, no other platform is even remotely affected. The bug is now corrected.
Own Id: OTP-8876

Erts 5.8.1

Fixed Bugs and Malfunctions

Very small floating point numbers generated errors when converting from list to float in some versions of the VM, this is now corrected so that i.e. list_to_float("1.0e-324"). returns 0.0 in all versions of Erlang.
Own Id: OTP-7178
Windows Vista and Windows 7 file system virtualization, which makes "old style" windows programs execute in a file system sandbox, was previously unintentionally turned on for the Erlang VM. This is now corrected so that i.e. writes to C:\Program Files\. without administrator privileges will fail.
Own Id: OTP-7405
Fix faulty 64-bit integer term output from drivers. Large 64-bits integers did not generate correct bignums and could even cause emulator crash. Only affects drivers using ERL_DRV_INT64 or ERL_DRV_UINT64, introduced in R13B03.
Own Id: OTP-8716
Fixed: inet:setopts(S, [{linger,{true,2}}]) returned {error,einval} for SCTP sockets. The inet_drv had a bug when checking the option size.
Own Id: OTP-8726 Aux Id: seq11617
Fix libm linking with --as-needed flag
When building with "--as-needed" linker flags on Linux the build will fail. This has now been fixed.
(Thanks to Christian Faulhammer)
Own Id: OTP-8728
gen_udp:connect/3 was broken for SCTP enabled builds. It did not detect remote end errors as it should.
Own Id: OTP-8729
Reduce the risk of integer wrapping in bin vheap size counting.
The vheap size series will now use the golden ratio instead of doubling and fibonacci sequences.
Own Id: OTP-8730
ETS ordered_set containing [] as key could cause strange thing to happen, like an infinite hanging ets:select.
Own Id: OTP-8732
reference() has been substituted for ref() in the documentation.
Own Id: OTP-8733
When a native compiled module called a not loaded non-native compiled module that had an on_load function, the export entries were trashed after code loading so on the next call from the native compiled module to the non-native compiled the emulator crashed. This bug has now been fixed.
Own Id: OTP-8736
HiPE-enabled Erlang VMs running on BSD systems sometimes generated messages like "Yikes! erts_alloc() returned misaligned address 0x8016a512c". Fixed. (Thanks to Mikael Pettersson.)
Own Id: OTP-8769
A race condition in erts_poll() could cause delay of poll for I/O.
Own Id: OTP-8773
Removed some potential vulnerabilities from the Erlang Port Mapper Daemon (epmd) and straightened up access control. Also removed hazardous interfaces allowing anyone on a machine to forcefully unregister other nodes. This means that the ei_unregister/erl_unregister interfaces in erl_interface is rendered not only error prone and mystifying as before, but totally ineffective. The old behaviour of unchecked node unregistering can be restored if needed, see epmd documentation for details.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-8780
Building in a source tree without prebuilt platform independent build results failed on the SSL examples when:
- cross building. This has been solved by not building the SSL examples during a cross build.
- building on Windows.
Own Id: OTP-8791
inet:getsockopt for SCTP sctp_default_send_param had a bug to not initialize required feilds causing random answers. It is now corrected.
Own Id: OTP-8795 Aux Id: seq11655
The hipe_bifs:get_hrvtime/0 BIF now always returns a real value even if the "perfctr" Linux kernel extension is not available. It used to return a dummy value. (Thanks to Mikael Pettersson.)
Own Id: OTP-8798
Calling a native-code compiled module with an on_load function could cause a crash. (Thanks to Mikael Pettersson.)
Own Id: OTP-8799
The emulator could crash while writing a crash dump if native-compiled modules had been loaded. (Thanks to Paul Guyot.)
Own Id: OTP-8801
The garbage collector could crash if invoked from native-compiled code after a call to a BIF. (Thanks to Paul Guyot.)
Own Id: OTP-8821
A rare memory leak in binary:matches is removed
Own Id: OTP-8823
For a socket in the HTTP packet mode, the return value from gen_tcp:recv/2,3 if there is an error in the header will be {ok,{http_error,String}} instead of {error,{http_error,String}} to be consistent with ssl:recv/2,3.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-8831

Improvements and New Features

ets:select_reverse/{1,2,3} are now documented.
Own Id: OTP-7863
External format of integers changed to make full use of all 32 bits of INTEGER_EXT. This is a compatible change as old code can read full 32-bit integers but only produce 28-bit integers as INTEGER_EXT.
Own Id: OTP-8540 Aux Id: seq11534
Large parts of the ethread library have been rewritten. The ethread library is an Erlang runtime system internal, portable thread library used by the runtime system itself.
Most notable improvement is a reader optimized rwlock implementation which dramatically improve the performance of read-lock/read-unlock operations on multi processor systems by avoiding ping-ponging of the rwlock cache lines. The reader optimized rwlock implementation is used by miscellaneous rwlocks in the runtime system that are known to be read-locked frequently, and can be enabled on ETS tables by passing the {read_concurrency, true} option upon table creation. See the documentation of ets:new/2 for more information. The reader optimized rwlock implementation can be fine tuned when starting the runtime system. For more information, see the documentation of the +rg command line argument of erl.
There is also a new implementation of rwlocks that is not optimized for readers. Both implementations interleaves readers and writers during contention as opposed to, e.g., the NPTL (Linux) pthread rwlock implementation which use either a reader or writer preferred strategy. The reader/writer preferred strategy is problematic since it starves threads doing the non-preferred operation.
The new rwlock implementations in general performs better in ERTS than common pthread implementations. However, in some extremely heavily contended cases this is not the case. Such heavy contention can more or less only appear on ETS tables. This when multiple processes do very large amounts of write locked operations simultaneously on the same table. Such use of ETS is bad regardless of rwlock implementation, will never scale, and is something we strongly advise against.
The new rwlock implementations depend on atomic operations. If no native atomic implementation is found, a fallback solution will be used. Using the fallback implies a performance degradation. That is, it is more important now than before to build OTP with a native atomic implementation.
The ethread library contains native atomic implementations for, x86 (32 and 64 bit), powerpc (32 bit), sparc V9 (32 and 64 bit), and tilera (32 bit). On other hardware gcc's builtin support for atomic memory access will be used if such exists. If no such support is found, configure will warn about no atomic implementation available.
The ethread library can now also use the libatomic_ops library for atomic memory accesses. This makes it possible for the Erlang runtime system to utilize optimized native atomic operations on more platforms than before. If configure warns about no atomic implementation available, try using the libatomic_ops library. Use the --with-libatomic_ops=PATH configure command line argument when specifying where the libatomic_ops installation is located. The libatomic_ops library can be downloaded from: http://www.hpl.hp.com/research/linux/atomic_ops/
The changed API of the ethread library has also caused modifications in the Erlang runtime system. Preparations for the to come "delayed deallocation" feature has also been done since it depends on the ethread library.
Note: When building for x86, the ethread library will now use instructions that first appeared on the pentium 4 processor. If you want the runtime system to be compatible with older processors (back to 486) you need to pass the --enable-ethread-pre-pentium4-compatibility configure command line argument when configuring the system.
Own Id: OTP-8544
erlang:localtime_to_universaltime({{2008, 8, 1}, {0, 0, 0}},true) when TZ=UTC now behaves consistently on all Unix platforms.
The problem fixed was originally reported by Paul Guyot on erlang-bugs mailing list:
http://www.erlang.org/pipermail/erlang-bugs/2008-November/001077.html
Own Id: OTP-8580
Optimization reducing memory consumption by two words per ETS object.
Own Id: OTP-8737
Fixes for unsupported halfword-emulator
Own Id: OTP-8745
NIF 64-bit integer support; enif_get_int64, enif_get_uint64, enif_make_int64, enif_make_uint64.
Own Id: OTP-8746
Alignment of trailing data in messages has been adjusted. This in order to be able to pass data of any type as trailing data in the future.
Own Id: OTP-8754
The obsolete/driver.h header file has been removed. It has been obsolete and deprecated since R8B. Drivers that still include obsolete/driver.h must be updated to include erl_driver.h.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-8758
Added erlang:system_info(build_type) which makes it easier to chose drivers, NIF libraries, etc based on build type of the runtime system.
The NIF library for crypto can now be built for valgrind and/or debug as separate NIF libraries that will be automatically loaded if the runtime system has been built with a matching build type.
Own Id: OTP-8760
Further lessened the memory requirements of ETS objects.
Own Id: OTP-8762
The broken elib_malloc alternate memory allocator has been removed. erlang:system_info(elib_malloc) will always return false, and in R15, erlang:system_info(elib_malloc) will fail with a badarg exception.
Own Id: OTP-8764
Calling erlang:system_info/1 with the new argument update_cpu_info will make the runtime system reread and update the internally stored CPU information. For more information see the documentation of erlang:system_info(update_cpu_info).
The CPU topology is now automatically detected on Windows systems with less than 33 logical processors. The runtime system will now, also on Windows, by default bind schedulers to logical processors using the default_bind bind type if the amount of schedulers is at least equal to the amount of logical processors configured, binding of schedulers is supported, and a CPU topology is available at startup.
Own Id: OTP-8765
The SMP ERTS internal child waiter thread used on Linux system with NPTL was unintentionally disabled during cross compilation rewrites (OTP-8323 in R13B03). It has now been re-enabled. Enabling it again gives a slight performance improvement.
Own Id: OTP-8774
epmd used to generate a message to the syslog when it started up, which could be annoying. This has been changed to only generate the message if the debug switch is given. (Thanks to Michael Santos.)
Own Id: OTP-8775
The scheduler wakeup threshold is now possible to adjust at system boot. For more information see the +swt command line argument of erl.
Own Id: OTP-8811
The undocumented function inet:ifget/2 has been improved to return interface hardware address (MAC) on platforms supporting getaddrinfo() (such as BSD unixes). Note it still does not work on all platforms for example not Windows nor Solaris, so the function is still undocumented.
Buffer overflow and field init bugs for inet:ifget/2 and inet:getservbyname/2 has also been fixed.
Thanks to Michael Santos.
Own Id: OTP-8816
Optimizations for MIPS when using gcc atomics. (Thanks to Steve Vinoski)
Own Id: OTP-8834
Lock optimization in timer functionality.
Own Id: OTP-8835

Known Bugs and Problems

Fix epmd and build environment to build on VxWorks
Own Id: OTP-8838

Erts 5.8

Fixed Bugs and Malfunctions

Driver threads, such as async threads, using port data locks peeked at the port status field without proper locking when looking up the driver queue.
Own Id: OTP-8475
The use of mmap() was unnecessarily disabled when cross compiling.
The configure arguments --with-ssl, and --with-odbc refused to accept libraries outside of $erl_xcomp_sysroot when cross compiling for no good reason.
The configure argument --with-odbc didn't handle the value yes correct.
The configure arguments --with-odbc, and --without-odbc have also been added to the configure help.
(Thanks to Steve Vinoski for reporting these issues)
Own Id: OTP-8484
A call to the BIF unregister(RegName) when a port had the name RegName registered in the runtime system without SMP support caused a runtime system crash. (Thanks to Per Hedeland for the bugfix and test case.)
Own Id: OTP-8487
The runtime system crashed if fewer logical processors were found than reported by sysconf( SC_NPROCESSORS_CONF).
Own Id: OTP-8549
Fix memory management bug causing crash of non-SMP emulator with async threads enabled. The bug did first appear in R13B03.
Own Id: OTP-8591 Aux Id: seq11554
Port locks could be prematurely destroyed.
Own Id: OTP-8612
The empd program could loop and consume 100% CPU time if an unexpected error occurred in listen() or accept(). Now epmd will terminate if a non-recoverable error occurs. (Thanks to Michael Santos.)
Own Id: OTP-8618
When kernel poll has been enabled, a livelock could in rare circumstances occur. Problem reported by Chetan Ahuja, fix by Mikael Pettersson.
Own Id: OTP-8632
Windows: Closing port of program that stalled without reading all data could deadlock scheduler thread.
Own Id: OTP-8641
On some combination of Montavista Linux on Cavium Octeon processors, some socket-related system calls returned other numbers than -1 for errors. This caused a core dump in inet_drv.c. Now the code works around this problem.
Own Id: OTP-8654
Missing memory barriers in erts_poll() could cause the runtime system to hang indefinitely.
Own Id: OTP-8658
ethr_rwmutex_tryrlock() acquired and refused to acquire a lock with inverted logic. The lock was however never acquired in a thread unsafe manner. (Thanks to JR Zhang for noting this issue)
Own Id: OTP-8662
Extreme combinations of register/unregister in a highly parallel SMP application could crash the VM. The error is corrected.
Own Id: OTP-8663
On Windows, files are now opened with FILE_SHARE_DELETE to get closer to Unix semantics.
Own Id: OTP-8667
erlang:system_info(multi_scheduling) sometimes erroneously returned enabled when it should have returned blocked.
Own Id: OTP-8675
Fix bug causing erlang:decode_packet and enif_make_string to generate faulty strings with negative character values for ascii values larger than 127. (Thanks to Paul Guyot)
Own Id: OTP-8685
open_port/2 with the spawn and spawn_executable options can include an {env,Env} option. In some cases unsetting variables would not work on Unix (typically if more variables were unset than were actually present in the environment).
Own Id: OTP-8701
A user defined CPU topology set via a call to erlang:system_flag(cpu_topology, CPUTopology) was not properly verified, and could in worst case cause an emulator crash. The emulator crash could only occur when a user defined CPU topology already existed and was redefined.
Own Id: OTP-8710

Improvements and New Features

The grammar for match specifications in ERTS users guide only described the tracing dialect of match specifications. An informal grammar for the ETS dialect is added.
Own Id: OTP-8086 Aux Id: seq11333
The module binary from EEP31 (and EEP9) is implemented.
Own Id: OTP-8217
New NIF API function enif_make_new_binary
Own Id: OTP-8474
The guard BIF is_boolean/1 (introduced in R10B) has now been included in the lists of BIFs allowed in guards in the Reference Manual.
Own Id: OTP-8477
Added function zip:foldl/3 to iterate over zip archives.
Added functions to create and extract escripts. See escript:create/2 and escript:extract/2.
The undocumented function escript:foldl/3 has been removed. The same functionality can be achieved with the more flexible functions escript:extract/2 and zip:foldl/3.
Record fields has been annotated with type info. Source files as been adapted to fit within 80 chars and trailing whitespace has been removed.
Own Id: OTP-8521
A regular expression with many levels of parenthesis could cause a buffer overflow. That has been corrected. (Thanks to Michael Santos.)
Own Id: OTP-8539
erlang:decode_packet(httph_bin,..) could return corrupt header strings or even crash the VM. This has been fixed. It only happened on 32-bit VM if the header name was unknown and between 16 and 20 characters long. Sockets with simular packet option did not suffer from this bug.
Own Id: OTP-8548
New NIF features:
- Send messages from a NIF, or from thread created by NIF, to any local process (enif_send)
- Store terms between NIF calls (enif_alloc_env, enif_make_copy)
- Create binary terms with user defined memory management (enif_make_resource_binary)
And some incompatible changes made to the API. For more information see the warning text in erl_nif(3).
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-8555
If the 'fop' program (needed for building PDF files) cannot not be found, it is now possible to build the HTML and man pages anyway (there will also be dummy PDF files with no real content created). (Thanks to Tuncer Ayaz.)
Own Id: OTP-8559
When defining macros the closing right parenthesis before the dot is now mandatory.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-8562
Local and imported functions now override the auto-imported BIFs when the names clash. The pre R14 behaviour was that auto-imported BIFs would override local functions. To avoid that old programs change behaviour, the following will generate an error:
- Doing a call without explicit module name to a local function having a name clashing with the name of an auto-imported BIF that was present (and auto-imported) before OTP R14A
- Explicitly importing a function having a name clashing with the name of an autoimported BIF that was present (and autoimported) before OTP R14A
- Using any form of the old compiler directive nowarn_bif_clash
If the BIF was added or auto-imported in OTP R14A or later, overriding it with an import or a local function will only result in a warning,
To resolve clashes, you can either use the explicit module name erlang to call the BIF, or you can remove the auto-import of that specific BIF by using the new compiler directive -compile({no_auto_import,[F/A]})., which makes all calls to the local or imported function without explicit module name pass without warnings or errors.
The change makes it possible to add auto-imported BIFs without breaking or silently changing old code in the future. However some current code ingeniously utilizing the old behaviour or the nowarn_bif_clash compiler directive, might need changing to be accepted by the compiler.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-8579
A bug in re that could cause certain regular expression matches never to terminate is corrected. (Thanks to Michael Santos and Gordon Guthrie.)
Own Id: OTP-8589
The erlang:open_port spawn and spawn_executable directives can include an {env,Env} directive to set up environment variables for the spawned process. A bug prevented applications from using {env,Env} to set an environment variable whose value ended with a '=' (equal sign) character; the trailing equal sign was mistaken as an indication that an environment variable was to be cleared from the environment of the spawned process. (Thanks to Steve Vinoski.)
Own Id: OTP-8614
receive statements that can only read out a newly created reference are now specially optimized so that it will execute in constant time regardless of the number of messages in the receive queue for the process. That optimization will benefit calls to gen_server:call(). (See gen:do_call/4 for an example of a receive statement that will be optimized.)
Own Id: OTP-8623
The functions file:advise/4 and file:datasync/1 have been added. (Thanks to Filipe David Manana.)
Own Id: OTP-8637
New NIF API functions: enif_make_atom_len, enif_make_existing_atom_len, enif_make_string_len, enif_get_atom_length, enif_get_list_length, enif_is_list, enif_is_tuple (by Tuncer Ayaz)
Own Id: OTP-8640
Support for using gcc's built-in functions for atomic memory access has been added. This functionality will be used if available and no other native atomic implementation in ERTS is available.
Own Id: OTP-8659
The number of spinlocks used when implementing atomic fall-backs when no native atomic implementation is available has been increased from 16 to 1024.
Own Id: OTP-8660
Writer preferred pthread read/write locks has been enabled on Linux.
Own Id: OTP-8661
The runtime system will by default bind schedulers to logical processors using the default_bind bind type if the amount of schedulers are at least equal to the amount of logical processors configured, binding of schedulers is supported, and a CPU topology is available at startup.
NOTE: If the Erlang runtime system is the only operating system process that binds threads to logical processors, this improves the performance of the runtime system. However, if other operating system processes (as for example another Erlang runtime system) also bind threads to logical processors, there might be a performance penalty instead. If this is the case you, are are advised to unbind the schedulers using the +sbtu command line argument, or by invoking erlang:system_flag(scheduler_bind_type, unbound).
Own Id: OTP-8666
The recently added BIFs erlang:min/2, erlang:max/2 and erlang:port_command/3 are now auto-imported (as they were originally intended to be). Due to the recent compiler change (OTP-8579), the only impact on old code defining it's own min/2, max/2 or port_command/3 functions will be a warning, the local functions will still be used. The warning can be removed by using -compile({no_auto_import,[min/2,max/2,port_command/3]}). in the source file.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-8669 Aux Id: OTP-8579
There is a new option 'exclusive' to file:open/2 that uses the OS O_EXCL flag where supported to open the file in exclusive mode.
Own Id: OTP-8670
Now, binary_to_term/2 is auto-imported. This will cause a compile warning if and only if a module has got a local function with that name.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-8671
Alignment of scheduler data and run queues were adjusted.
Own Id: OTP-8673
Call time breakpoint tracing
- Introduce a call_time option to erlang:trace_pattern/3.This option enables call time breakpoint tracing on code that is executed by processes with call tracing enabled. Call time tracing stores the number of calls and the time spent of each function with this trace pattern enabled. The information can be retrieved with erlang:trace_info/2
- Add a scheduler array for BpData. To solve the issue of multiple schedulers constantly updating the head pointer to the bp data wheel, each scheduler now has its own entrypoint to the wheel. This head pointer can be updated without a locking being taken.
Teach call count tracing to use atomics
- Call count previously used a global lock for accessing and writing its counter in the breakpoint. This is now changed to atomics instead.
- The change will let call count tracing and cprof to scale better when increasing the number of schedulers.
Own Id: OTP-8677
eprof has been reimplemented with support in the Erlang virtual machine and is now both faster (i.e. slows down the code being measured less) and scales much better. In measurements we saw speed-ups compared to the old eprof ranging from 6 times (for sequential code that only uses one scheduler/core) up to 84 times (for parallel code that uses 8 cores).
Note: The API for the eprof has been cleaned up and extended. See the documentation.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-8706

Erts 5.7.5.2

Known Bugs and Problems

Two bugs in gen_sctp has been corrected: getopts/setopts hence also send could only be called from socket owner, and options 'linger', 'rcvbuf' and 'sndbuf' was read from wrong protocol layer hence read wrong values by getopts.
Own Id: OTP-9544

Erts 5.7.5.1

Fixed Bugs and Malfunctions

Driver threads, such as async threads, using port data locks peeked at the port status field without proper locking when looking up the driver queue.
Own Id: OTP-8475
A call to the BIF unregister(RegName) when a port had the name RegName registered in the runtime system without SMP support caused a runtime system crash. (Thanks to Per Hedeland for the bugfix and test case.)
Own Id: OTP-8487
Fix memory management bug causing crash of non-SMP emulator with async threads enabled. The bug did first appear in R13B03.
Own Id: OTP-8591 Aux Id: seq11554

Erts 5.7.5

Fixed Bugs and Malfunctions

Fix binary_to_term crash on compressed term with corrupt size field.
Own Id: OTP-8336
Processes and/or ports could get stuck on a blocked scheduler when erlang:system_flag(multi_scheduling, block) was used.
Processes and/or ports could get stuck on an offline scheduler when schedulers online were reduced using erlang:system_flag(schedulers_online, SchedulersOnline).
Own Id: OTP-8342
Building on Windows will now work if the paths to mc.exe and rc.exe contain spaces. The README.win32 file has been updated with some information about building using Visual Studio 2008. (Thanks to Andrew Thompson.)
Own Id: OTP-8345
EPMD now correctly handles the extra data field which can be given in the ALIVE2_REQ request and retrieved in the PORT2_RESP response. (Thanks to Klas Johansson.)
Own Id: OTP-8361
The configure test for reliable floating point exceptions has been update to work on modern versions of Mac OS X. (Thanks to Trannie Carter.)
Own Id: OTP-8368
ERTS makefiles used to detect the use of a gcc C compiler by checking if CC equaled gcc. That is, the makefiles failed to detect gcc C compilers with other command line names than gcc. `configure' now substitute GCC into the makefiles. If CC is a gcc C compiler, GCC will have the value yes. (Thanks to Jean-Sébastien Pédron)
Own Id: OTP-8373
ETS bug causing the memory counter from ets:info for ordered_set's to sometimes get out of synch and absurdly high.
Own Id: OTP-8377 Aux Id: seq11442
Immediately repeated multi-scheduling block/unblock cycles using erlang:system_flag(multi_scheduling, block | unblock) could deadlock the runtime system.
Own Id: OTP-8386
A number of bugs concerning re and unicode are corrected:
re:compile no longer loses unicode option, which also fixes bug in re:split.
re:replace now handles unicode charlist replacement argument
re:replace now handles unicode RE charlist argument correctly
re:replace now handles binary unicode output correctly when nothing is replaced.
Most code, testcases and error isolation done by Rory Byrne.
Own Id: OTP-8394
The loading of native code was not properly atomic in the SMP emulator, which could cause crashes. Also a per-MFA information table for the native code has now been protected with a lock since it turns that it could be accessed concurrently in the SMP emulator. (Thanks to Mikael Pettersson.)
Own Id: OTP-8397
Fix processes in exiting status that are about to be scheduled, to not be allowed to garbage collect.
Own Id: OTP-8420
Removed bogus "\011" character sequence in documentation.
Own Id: OTP-8422
The resolver routines failed to look up the own node name as hostname, if the OS native resolver was erroneously configured, bug reported by Yogish Baliga, now fixed.
The resolver routines now tries to parse the hostname as an IP string as most OS resolvers do, unless the native resolver is used.
The DNS resolver inet_res and file resolver inet_hosts now do not read OS configuration files until they are needed. Since the native resolver is default, in most cases they are never needed.
The DNS resolver's automatic updating of OS configuration file data (/etc/resolv.conf) now uses the 'domain' keyword as default search domain if there is no 'search' keyword.
Own Id: OTP-8426 Aux Id: OTP-8381
The re module: A regular expression with an option change at the start of a pattern that had top-level alternatives could cause overwriting and/or a crash. (Thanks to Michael Santos.)
Own Id: OTP-8438
Harmless buffer overflow by one byte in asn1 and ram_file_drv.
Own Id: OTP-8451

Improvements and New Features

Improved GC performance after BIF/NIF call when a lot of heap fragments was created. This will mainly benefit NIFs that return large compound terms.
Own Id: OTP-8240
Incompatible changes in the experimental NIF feature.
- Changed the NIF function prototypes in order to allow more than 3 function arguments.
- enif_get_data renamed as enif_priv_data.
- enif_make_string got a third argument for character encoding.
- The return value of erlang:load_nif/2 on error changed.
Read more in the documentation of erl_nif and erlang:load_nif/2
.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-8304
Cross compilation improvements and other build system improvements.
Most notable:
- Lots of cross compilation improvements. The old cross compilation support was more or less non-existing as well as broken. Please, note that the cross compilation support should still be considered as experimental. Also note that old cross compilation configurations cannot be used without modifications. For more information on cross compiling Erlang/OTP see the $ERL_TOP/INSTALL-CROSS.md file.
- Support for staged install using DESTDIR. The old broken INSTALL_PREFIX has also been fixed. For more information see the $ERL_TOP/INSTALL.md file.
- Documentation of the release target of the top Makefile. For more information see the $ERL_TOP/INSTALL.md file.
- make install now by default creates relative symbolic links instead of absolute ones. For more information see the $ERL_TOP/INSTALL.md file.
- $ERL_TOP/configure --help=recursive now works and prints help for all applications with configure scripts.
- Doing make install, or make release directly after make all no longer triggers miscellaneous rebuilds.
- Existing bootstrap system is now used when doing make install, or make release without a preceding make all.
- The crypto and ssl applications use the same runtime library path when dynamically linking against libssl.so and libcrypto.so. The runtime library search path has also been extended.
- The configure scripts of Erl_interface and ODBC now search for thread libraries and thread library quirks the same way as ERTS do.
- The configure script of the odbc application now also looks for odbc libraries in lib64 and lib/64 directories when building on a 64-bit system.
- The config.h.in file in the erl_interface application is now automatically generated in instead of statically updated which reduces the risk of configure tests without any effect.
(Thanks to Henrik Riomar for suggestions and testing)
(Thanks to Winston Smith for the AVR32-Linux cross configuration and testing)
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-8323
NIF improvements:
- Driver API for multi-threading made available for NIFs.
- Support for mempory managed (garbage collected) resource objects. A way to pass "pointers" to native data structures between C and Erlang in a safe way.
- Support for references, floats and term comparison.
- Various new functions, like enif_inspect_iolist_as_binary, enif_make_sub_binary, enif_get_string, enif_get_atom, enif_make_tuple_from_array, enif_make_list_from_array, enif_make_existing_atom.
Own Id: OTP-8335
Minor alignment adjustments of scheduler specific data.
Own Id: OTP-8341
The documentation is now possible to build in an open source environment after a number of bugs are fixed and some features are added in the documentation build process.
- The arity calculation is updated.
- The module prefix used in the function names for bif's are removed in the generated links so the links will look like "http://www.erlang.org/doc/man/erlang.html#append_element-2" instead of "http://www.erlang.org/doc/man/erlang.html#erlang:append_element-2".
- Enhanced the menu positioning in the html documentation when a new page is loaded.
- A number of corrections in the generation of man pages (thanks to Sergei Golovan)
- The legal notice is taken from the xml book file so OTP's build process can be used for non OTP applications.
Own Id: OTP-8343
There is new erlang:binary_to_term/2 BIF that takes an option list. The option safe can be used to prevent creation of resources that are not garbage collected (such as atoms). (Thanks to Jayson Vantuyl.)
Own Id: OTP-8367
The default settings for garbage collection of binaries has been adjusted to be less aggressive than in R13B03. It is now also possible configure the settings for binary GC. See the documentation for spawn_opt/2-5, erlang:system_info/1, erlang:system_flag/2, process_flag/2-3, erlang:trace/3, and the documentation for erl for the new command line options +hms and +hmbs.
Own Id: OTP-8370
A bug causing memory corruption in re:run() has been corrected. (Thanks to Yamashina Hio.)
Own Id: OTP-8375
The -Werror option for erlc and the compiler option warnings_as_errors will cause warnings to be treated as errors. (Thanks to Christopher Faulet.)
Own Id: OTP-8382
Explicit top directories in archive files are now optional.
For example, if an archive (app-vsn.ez) just contains an app-vsn/ebin/mod.beam file, the file info for the app-vsn and app-vsn/ebin directories are faked using the file info from the archive file as origin. The virtual directories can also be listed. For short, the top directories are virtual if they does not exist.
Own Id: OTP-8387
An unnecessary lock operation in os:timestamp/0 has been eliminated, making it slightly more efficient. (Thanks to Jonas Falkevik and Tuncer Ayaz.)
Own Id: OTP-8390
There is a new +t emulator option for changing the maximum number of atoms. (Thanks to Julien Barbot.)
Own Id: OTP-8405
Fixed numerous compiler warnings generated by gcc 4.4.1 and tile-cc 2.0.1.78377 when compiling the runtime system.
Own Id: OTP-8412
configure learned the option --enable-m32-build to force the building of a 32-bit run-time on systems where the default C compiler generates 64-bit executables by default.
Own Id: OTP-8415
HiPE now works in the 64-bit emulator on Mac OS X. (Thanks to Geoff Cant.)
Own Id: OTP-8416
Improved handling of symbolic links to escripts
Own Id: OTP-8417
Add lock profiling tool.
The Lock profiling tool, lcnt, can make use of the internal lock statistics when the runtime system is built with this feature enabled.
This provides a mechanism to examine potential lock bottlenecks within the runtime itself.
- Add erts_debug:lock_counters({copy_save, bool()}). This option enables or disables statistics saving for destroyed processes and ets-tables. Enabling this might consume a lot of memory.
- Add id-numbering for lock classes which is otherwise undefined.
Own Id: OTP-8424
Removed spurious options to the emulator from escript.
Own Id: OTP-8427
Minor documentation fixes. Mainly anchor adjustments.
Own Id: OTP-8457

Erts 5.7.4

Fixed Bugs and Malfunctions

An insufficient stack allocation was made when reading CPU information on BSD operating systems. (Thanks Michael Turner and Akira Kitada)
Own Id: OTP-8207
A bug when supplying an argument without a dash directly after the program name when starting erlang could prevent distribution to start. This is now corrected.
Own Id: OTP-8209
A ticker process could potentially be blocked indefinitely trying to send a tick to a node not responding. If this happened, the connection would not be brought down as it should.
Own Id: OTP-8218
Using certain firewalls (i.e. MS IAS Client and certain versions of COMODO) could expose an undocumented behaviour in the Win32 socket interface causing the name resolution calls to hang infinitely. This is now worked around by adding possibilities for port programs under Windows to use overlapped I/O on their standard input/output file handles.
Own Id: OTP-8230
Fixed bug on ETS tables with write_concurrency. The emulator could crash when doing a select or match with a bound key without finding any object.
Own Id: OTP-8242
The information-request / information-response, and group-leader-change-request / group-leader-changed-response signal pairs described below did not always adhere to the signal order guarantees of Erlang's signal model in the runtime system with SMP support. These signals could for example sometimes pass exit signals.
The following BIFs behaviors can be modeled as if an asynchronous information-request signal is sent to Pid. If Pid is alive, it responds with an asynchronous information-response signal; otherwise, the runtime system responds with a no-such-process signal. When the response is received, the caller transforms it into the result of the BIF.
- is_process_alive(Pid)
- erlang:process_display(Pid, Type)
- process_info(Pid)
- process_info(Pid, ItemSpec)
When Pid resides on the same node as the caller of group_leader(GroupLeader, Pid), the group_leader/2 BIFs behavior can be modeled as if an asynchronous group-leader-change-request signal is sent to Pid. If Pid is alive, it responds with an asynchronous group-leader-changed-response signal; otherwise, the runtime system responds with a no-such-process signal. When the response is received, the caller transforms it into the result of the BIF. The distributed case which only consists of an asynchronous group-leader-change-request signal and no response is not effected.
Own Id: OTP-8245
Errors in the system_profile documentation has been corrected.
Own Id: OTP-8257
Low watermark socket option modified high watermark instead of low watermark in the inet_driver. (Thanks to Feng Yu and Tuncer Ayaz)
Own Id: OTP-8279
A race condition could cause the runtime system with SMP support to end up in a completely unresponsive state.
Own Id: OTP-8297

Improvements and New Features

The use of pthread_cond_timedwait() have been completely removed from the runtime system. This since its behavior is unpredictable when the system clock is suddenly changed. The previous use of it was harmless.
Own Id: OTP-8193
The documentation is now built with open source tools (xsltproc and fop) that exists on most platforms. One visible change is that the frames are removed.
Own Id: OTP-8201
A new garbage collecting strategy for binaries which is more aggressive than the previous implementation. Binaries now has a virtual binary heap tied to each process. When binaries are created or received to a process it will check if the heap limit has been reached and if a reclaim should be done. This imitates the behavior of ordinary Erlang terms. The virtual heaps are grown and shrunk like ordinary heaps. This will lessen the memory footprint of binaries in a system.
Own Id: OTP-8202
The ErlDrvTermData term types used by driver_output_term() and driver_send_term() have been extended with the term types ERL_DRV_INT64, and ERL_DRV_UINT64 for passing 64-bit integers. Also the 64-bit integer data types ErlDrvSInt64 and ErlDrvUInt64 have been introduced.
For more information see the erl_driver(3) documentation.
Own Id: OTP-8205
[escript] The restriction that the first line in escripts must begin with #! has been removed.
[escript] Some command line options to the escript executable has now been documented. For example you can run an escript in the debugger by just adding a command line option.
[escript] The documentation of the escript header syntax has been clarified. For example the header is optional. This means that it is possible to directly "execute" .erl, .beam and.zip files.
Own Id: OTP-8215
The instruction for building OTP on Windows was outdated and incomplete, the document is updated.
Also the otp_build script required windows drives to show up in Cygwin using the /cygdrive prefix. That requirement is now removed.
Own Id: OTP-8219
A module can have native implemented functions (NIFs) that are dynamically loaded by calling erlang:load_nif/2. This is an experimental feature that is not yet intended for production systems. It is released with intention to get some early feedback on the interfaces before they are carved in stone.
Own Id: OTP-8220
The float/1 BIF would always force a garbage collection. The BIFs size/1, byte_size/1, bit_size/1, abs/1, and round/1 would force a garbage-collection if the result was not a sufficiently small integer.
Own Id: OTP-8221
The erlang:port_command/3 BIF has been added. erlang:port_command/3 is currently not auto imported, but it is planned to be auto imported in OTP R14. For more information see the erlang documentation.
Own Id: OTP-8225
'configure --enable-darwin-64bit' would fail if Snow Leopard had been booted with the 64-bit kernel. (Thanks to Ryan M. Graham.)
Own Id: OTP-8236

Erts 5.7.3

Fixed Bugs and Malfunctions

On Windows, open_port({spawn,Command},Opts) could not run executables with spaces in the path or filename, regardless of quoting efforts. While open_port({spawn_executable,Exec},Opts) can run any executable, it was still impossible to use 'spawn' to do the same thing. This is now corrected.
Own Id: OTP-8055
The scheduler bind type processor_spread spread schedulers too much on large NUMA systems.
The new scheduler bind type spread spreads schedulers as much as possible, and behaves as processor_spread previously did. For more information see the documentation of the +sbt command line argument in the erl documentation, and the documentation of erlang:system_flag(scheduler_bind_type, SchedulerBindType).
Own Id: OTP-8063
Automatically detected CPU topology on Linux system could erroneously contain logical processors with -1 as identifiers. This happened when sysconf(_SC_NPROCESSORS_CONF) returned a value larger than the amount of logical processors found.
Own Id: OTP-8064
When the minimal term [] (end of list) was sent as the complete message to a process on another node, and received there, it could not be decoded. This bug is now corrected. Fortunately [] is uncommon as the complete message in real applications but it is a serious bug anyway.
Own Id: OTP-8092
A bug when the floating point exception pointer was not initialized has been corrected. It manifested itself on CentOS 5.1 sometimes when a floating point value was sent to a remote node. Bug reported and patch suggested by David Reiss, confirmed by Mikael Pettersson.
Some build problems on IRIX was also corrected. Problem reported by Patrick Baggett, patch by Mikael Pettersson.
Own Id: OTP-8095
A terminating process could erroneously unregister a name for another process. This could occur under the following conditions: The name of the terminating process was unregistered and then registered for another process simultaneously as the process that first had the name was terminating.
Own Id: OTP-8099 Aux Id: seq11344
Running erlc in a very deep directory (with a path length of more 256 or more characters) would cause the emulator to crash in a call to list_to_atom/1. (Thanks to Chris Newcombe.)
Own Id: OTP-8124
A deadlock of the runtime system could occur when unregistering the name of a port.
Own Id: OTP-8145
Makefile.in has been updated to use the LDFLAGS environment variable (if set). (Thanks to Davide Pesavento.)
Own Id: OTP-8157
The pthread rwlock implementation on Linux could cause starvation of writers. We, therefore, now use our own rwlock implementation on Linux.
Own Id: OTP-8158
Open source Erlang builds are updated to work well on Snow Leopard (MacOS X 10.6)
Own Id: OTP-8168
A call to erlang:system_info(schedulers_online) could end up in an infinite loop. This happened if the amount of schedulers was larger than one, the amount of schedulers online was one, and someone was blocking multi-scheduling.
Own Id: OTP-8169
An error in erlang:system_profile/2 could cause timestamped messages to arrive out of order in the SMP case. This has now been fixed.
Own Id: OTP-8171
binary_to_atom/2 and binary_to_existing_atom/2 would leak memory if the binary contained unaligned data.
Own Id: OTP-8192
The async thread pool in the runtime system without SMP support used a memory allocator that was not thread safe for async jobs.
Own Id: OTP-8194

Improvements and New Features

Processor internal NUMA nodes are now supported in the ERTS internal CPU topology representation. For more information see the documentation of the +sct command line argument in the erl documentation, and the documentation of erlang:system_info(cpu_topology).
Own Id: OTP-8041
Documentation for ets improved about concurrency.
Own Id: OTP-8050
Emulator flags in an escript were earlier inherited to emulators started from the emulator running the escript. For example when an escript invoked os:cmd("erl"), the new emulator were given erroneous emulator flags. This bug has now been fixed
Escript filenames may now contain dots.
Own Id: OTP-8060
Made some BIFs non-recursive (relational operators,hash and phash) to limit internal stack usage.
Own Id: OTP-8065
Fixed Windows specific bug in erl_prim_loader. Now it handles the root directory (e.g. c:/) better. This bug affected the directory listing in the debugger.
Own Id: OTP-8080
A TCP socket with option {packet,4} could crash the emulator if it received a packet header with a very large size value (>2Gb). The same bug caused erlang:decode_packet/3 to return faulty values. (Thanks to Georgos Seganos.)
Own Id: OTP-8102
The maximum size of the export table has been raised from 65536 to 524288 entries.
Own Id: OTP-8104 Aux Id: seq11345
The file module has now a read_line/1 function similar to the io:get_line/2, but with byte oriented semantics. The function file:read_line/1 works for raw files as well, but for good performance it is recommended to use it together with the 'read_ahead' option for raw file access.
Own Id: OTP-8108
Fixed bug causing emulator crash when reading a term in external format containing a corrupt list with a negative length.
Own Id: OTP-8117
New emulator flag +sss, to set stack size of scheduler threads.
Own Id: OTP-8119
The Windows utility Erlsrv, run in interactive mode now accepts options for registering internal service name and description field of Windows registry database.
Own Id: OTP-8132
erlang:demonitor(Mon, [flush]) has been optimized. Previously it always searched the message queue of the caller for a 'DOWN' message. Current implementation only search the message queue when necessary. It is quite common that the search is not necessary.
A new option info has been added to erlang:demonitor/2. For more information see the erlang documentation.
Own Id: OTP-8143
I/O tasks could unnecessarily be rescheduled. This was harmless, but not useful work.
Own Id: OTP-8148
Minor improvements of erlang:memory/[1,2].
Own Id: OTP-8152
New configuration option to enable use of shared zlib.
Own Id: OTP-8155
Fixed smp bug in ETS that could cause emulator crash when table with more than 1000 objects accessed by several processes, including calls to variants of select or match combined with concurrent object deletion.
Own Id: OTP-8166 Aux Id: seq11392
The code path interpretation is now more relaxed. The flag -code_path_choice now defaults to relaxed instead of strict. See the documentation of code and init for more info.
Own Id: OTP-8170
Load balancing of run queues and check for I/O are triggered more often than before in situations where processes are scheduled often but are doing very little work each time they execute.
Own Id: OTP-8172
Call tracing binary comprehensions would cause an emulator crash. (Thanks to Paul Mineiro.)
Own Id: OTP-8179
binary_to_term/1 would crash the emulator instead of generating a badarg exception when given certain invalid terms. (Thanks to Scott Lystig Fritchie.)
Own Id: OTP-8180

Erts 5.7.2

Fixed Bugs and Malfunctions

Crash dumps should now cause less problems for the crashdump_viewer application. (For processes where arity was non-zero, the arguments are now longer printed - they used to be printed in a format that was not parseable.)
Own Id: OTP-7472 Aux Id: seq11019, 11292
Processes could potentially get stuck on an offline scheduler.
Own Id: OTP-7990
binary_to_atom/2 and binary_to_existing_atom/2 could leak memory if they caused a badarg exception.
Own Id: OTP-7997
A process could under very rare circumstances erroneously be resumed.
Own Id: OTP-8000
Load balancing between schedulers could under rare circumstances cause an emulator crash.
Own Id: OTP-8008
erlang:memory(processes_used) always returned 0 instead of the correct value. (Thanks to Geoff Cant)
Own Id: OTP-8022

Improvements and New Features

Major improvements of the Erlang distribution for Erlang runtime systems with SMP support. Previously distribution port locks were heavily contended, and all encoding and decoding for a specific distribution channel had to be done in sequence. Lock contention due to the distribution is now negligible and both encoding and decoding of Erlang messages can be done in parallel.
The old atom cache protocol used by the Erlang distribution has been dropped since it effectively prevented all parallel encoding and decoding of messages passed over the same distribution channel.
A new atom cache protocol has been introduced which isolates atom cache accesses and makes parallel encoding and decoding of messages passed over the same distribution channel possible. The new atom cache protocol also use an atom cache size 8 times larger than before. The new atom cache protocol is documented in the ERTS users guide.
Erlang messages received via the distribution are now decoded by the receiving Erlang processes without holding any distribution channel specific locks. Erlang messages and signals sent over the distribution are as before encoded by the sending Erlang process, but now without holding any distribution channel specific locks during the encoding. That is, both encoding and decoding can be and are done in parallel regardless of distribution channel used.
The part that cannot be parallelized is the atom cache updates. Atom cache updates are therefore now scheduled on the distribution port. Since it is only one entity per distribution channel doing this work there is no lock contention due to the atom cache updates.
The new runtime system does not understand the old atom cache protocol. New and old runtime systems can however still communicate, but no atom cache will be used.
Own Id: OTP-7774
Fixed a bug that caused error logging from driver_select sometimes with additional symptoms such as failing IP communications or even an emulator crash.
Own Id: OTP-7898 Aux Id: seq11304
Improved SMP concurrency for ETS tables. Several mutating operations can now be performed truly concurrent on different records of the same table. To support this, the table has to be created with option write_concurrency, as it is achieved at the expense of some execution and memory overhead. ets:select and select_count has also been improved for all tables to not acquire exclusive table lock during the iteration.
Own Id: OTP-7922
erl (that is erl.exe and dyn_erl) and erlexec has been made more dynamic so no hard coded paths needs to added at installation time to erl (that is erl.ini and erl). Reltool will make use of this in a future release.
Own Id: OTP-7952
Added functionality to get higher resolution timestamp from system. The erlang:now function returns a timestamp that's not always consistent with the actual operating system time (due to resilience against large time changes in the operating system). The function os:timestamp/0 is added to get a similar timestamp as the one being returned by erlang:now, but untouched by Erlangs time correcting and smoothing algorithms. The timestamp returned by os:timestamp is always consistent with the operating systems view of time, like the calendar functions for getting wall clock time, but with higher resolution. Example of usage can be found in the os manual page.
Own Id: OTP-7971
Two new options are added to open_port - spawn_executable which runs external executables in a controlled way, and spawn_driver which only opens port to loaded Erlang drivers. See the erlang manual page for details.
Own Id: OTP-7995
New functionality in ETS to transfer the ownership of a table. A table can either change owner be declaring an "heir", another process that will inherit the table if the owner terminates. A table can also change owner by calling a new function ets:give_away.
Own Id: OTP-8006
Updates to Tilera build environment.
Own Id: OTP-8009
A stack trace was unnecessarily saved during process termination.
Own Id: OTP-8014
User defined CPU topology and scheduler bind type can now be set from the command line when starting an emulator. For more information see the documentation of the +sct, and the +sbt emulator flags in the erl documentation.
The CPU topologies returned from erlang:system_info/1 and erlang:system_flag/2 now always contain the processor level, also when not strictly necessary.
Own Id: OTP-8030
Various fixes in ETS: ets:first could return a deleted key in a fixated table. ets:lookup could return objects out of order if a deleted object was re-inserted into a fixed bag. ets:delete_object could fail to delete duplicate objects in a duplicate_bag.
Own Id: OTP-8040

Erts 5.7.1

Fixed Bugs and Malfunctions

Fixed a bug on Windows that could make gen_tcp:send hang trying to send an iolist of more than 16 binaries.
Own Id: OTP-7816
The runtime system could under rare circumstances crash during load balancing.
Own Id: OTP-7908 Aux Id: otp-7500
run_erl uses fallback if Unix98 pseudo-terminal is not present on host.
Own Id: OTP-7916 Aux Id: seq11249
A message buffer memory leak in the runtime system without smp support has been fixed.
Own Id: OTP-7941
Attempting to append a binary of 16Mb or greater to another binary using the bit syntax would cause a system_limit exception. There was also several cases when constructing binaries when a badarg exception was generated when it should have been system_limit.
Own Id: OTP-7942
The runtime system with SMP support failed to terminate the caller of link(RemotePid) properly, if RemotePid was the pid of a process on an unreachable node. The calling process was in this case marked as exiting, but never terminated.
Own Id: OTP-7946

Improvements and New Features

Rudimentary support for cross compiling is added to the source release. The support is still in its infancy and has only been used to cross compile on Linux for a different cpu architecture and a different Linux version, but should be extendible to support other platforms as well. The cross configuration files with examples are placed in $ERL_TOP/xcomp/. View README.xcomp and run $ERL_TOP/otp_build -help for further information.
Own Id: OTP-7854
The escape sequence \{ which was given a new interpretation in R13A has retained its old meaning (the ASCII code for {), which means that codes greater than 255 have to be stated using hexadecimal characters (for example, \x{AAA}). The escape sequence \xH where H is a hexadecimal character followed by something else but a hexadecimal character is no longer valid (incompatibility with R13A). Character codes less than 256 can be stated using two hexadecimal characters (for example, \x0D).
Own Id: OTP-7891 Aux Id: OTP-7855
The term_to_binary/1 BIF used to be implemented with recursive C code, which could cause the Erlang emulator to terminate because of a stack overflow.
Also fixed some minor issues in term_to_binary/1 and binary_to_term/1 pointed out by Matthew Dempsky.
Own Id: OTP-7894
Several glitches and performance issues in the Unicode and I/O-system implementation of R13A have been corrected.
Own Id: OTP-7896 Aux Id: OTP-7648 OTP-7887
Minor documentation improvements of the scheduler_bind_type argument of erlang:system_flag/2, and the scheduler_bind_type, and the scheduler_bindings arguments of erlang:system_info/1.
Own Id: OTP-7901 Aux Id: OTP-7777
There is a new BIF erlang:make_tuple/3.
Own Id: OTP-7913

Erts 5.7

Fixed Bugs and Malfunctions

OpenSource:
FreeBSD leap-seconds are handled according to patch submitted by OpenSource user Kenji Rikitake. No test case covers this functionality (unsupported platform).
Own Id: OTP-7609
A corrected bug in ETS for bag and duplicate_bag. A delete/2 or lookup_element/3 could miss objects in a fixed table if one or more objects with the same key had already been deleted.
Own Id: OTP-7665
A new driver call-back stop_select is introduced to allow drivers to de-select and then close a file descriptor in a safe way in a SMP emulator. The old way was not strictly according to posix standard and could in some rare cases lead to unexpected behavior. A new flag ERL_DRV_USE can be passed to driver_select() to tell it that the descriptor should be closed. stop_select is then called when it is safe to do so. Old drivers will however still work as before.
Own Id: OTP-7670
A bug fixed for TCP sockets with option {packet,http}. An HTTP request with an absolute URI was returned with a corrupt path string. This bug did only exist in R12B-4 and R12B-5.
Own Id: OTP-7682 Aux Id: OTP-7647
run_erl did in some cases fail to extract control sequences from to_erl (like: winsize=X,Y) and did instead send them to be interpreted by the erlang shell.
Own Id: OTP-7688
A bug in the installer on Windows not updating file associations properly is now corrected.
Own Id: OTP-7746
More space than necessary could be allocated in binaries when appending to a binary (also in a binary comprehension) and the data appended did not consist of wholes bytes (e.g. 13 bits).
Own Id: OTP-7747
The gen_sctp option sctp_peer_addr_params, #sctp_paddrparams{address={IP,Port} was erroneously decoded in the inet driver. This bug has now been corrected.
Own Id: OTP-7755
Outstanding async driver jobs leaked memory if the issuing port died before the async jobs completed.
Own Id: OTP-7784
A bug in the dynamic library loading affecting, among others, OpenSolaris is now corrected. (Thanks to Paul Fisher.)
Own Id: OTP-7796
run_erl compile errors fixed for FreeBSD
Own Id: OTP-7817
A bug in the inet driver for SCTP on Solaris showing for e.g gen_sctp:abort/1 and gen_sctp:eof/1 has been corrected. Patch suggestion by Simon Cornish.
Own Id: OTP-7866

Improvements and New Features

The order of objects visited in select for ordered_set is now documented.
Own Id: OTP-7339
The runtime system with SMP support now uses multiple, scheduler specific run queues, instead of one globally shared run queue.
The lock protecting the shared run queue was heavily contended, and the shared run queue also caused Erlang processes to randomly migrate between schedulers with negative cache effects as a result.
With the current scheduler specific run queue solution, lock contention due to run queue protection has been reduced, and Erlang processes are only migrated when needed to balance the load between the schedulers. The reduced amount of migration also reduce lock contention on locks protecting the scheduler specific instances of the erts internal memory allocators.
The scheduler specific run queues are also a necessity for a lot of future planned NUMA (Non-Uniform Memory Access) specific optimizations.
Own Id: OTP-7500
Support for Unicode is implemented as described in EEP10. Formatting and reading of unicode data both from terminals and files is supported by the io and io_lib modules. Files can be opened in modes with automatic translation to and from different unicode formats. The module 'unicode' contains functions for conversion between external and internal unicode formats and the re module has support for unicode data. There is also language syntax for specifying string and character data beyond the ISO-latin-1 range.
The interactive shell will support input and output of unicode characters when the terminal and operating system supports it.
Please see the EEP and the io/io_lib manual pages as well as the stdlib users guide for details.
I/O-protocol incompatibilities:
The ioprotocol between io_Server and client is updated to handle protocol data in unicode formats. The updated protocol is now documented. The specification resides in the stdlib _users manual, which is a new part of the manual.
io module incompatibilities:
The io:putchars, io:get_chars and io:get_line all handle and return unicode data. In the case where binaries can be provided (as to io:put_chars), they shall be encoded in UTF-8. When binaries are returned (as by io:get_line/get_chars when the io_server is set in _binary mode) the returned data is also always encoded as UTF-8. The file module however still returns byte-oriented data, why file:read can be used instead of io:get_chars to read binary data in ISO-latin-1.
io_lib module incompatibilities:
io_lib:format can, given new format directives (i.e "~ts" and "~tc"), return lists containing integers larger than 255.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-7648 Aux Id: OTP-7580 OTP-7514 OTP-7494 OTP-7443 OTP-7181 EEP10 EEP11
The format of the string returned by erlang:system_info(system_version) (as well as the first message when Erlang is started) has changed. The string now contains the both the OTP version number as well as the erts version number.
Own Id: OTP-7649
Message passing has been further optimized for parallel execution. Serial message passing is slightly more expensive than before, but parallel send to a common receiver is much cheaper.
Own Id: OTP-7659
Lock contention on the atom table lock when decoding Erlang terms on the external format has been drastically reduced.
Own Id: OTP-7660
The undocumented, unsupported, and deprecated guard BIF is_constant/1 has been removed.
* INCOMPATIBILITY with R12B *
Own Id: OTP-7673
The Erlang process lock implementation has been improved by Mat Hostetter at Tilera Corporation.
Own Id: OTP-7692
A {nodedown, Node} message passed by the net_kernel:monitor_nodes/X functionality is now guaranteed to be sent after Node has been removed from the result returned by erlang:nodes/Y.
Own Id: OTP-7725
The short-circuit operators andalso and orelse no longer guarantees that their second argument is either true or false. As a consequence, andalso/orelse are now tail-recursive.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-7748
A new BIF, lists:keyfind/3, has been added. It works like lists:keysearch/3 except that it does not wrap the returned tuple in a value tuple in case of success. (Thanks to James Hague for suggesting this function.)
Own Id: OTP-7752
Optimization for drivers by creating small binaries direct on process heap.
Own Id: OTP-7762
I bsl N could cause the Erlang virtual machine to run of memory instead generating a system_limit if N was absurdly huge. (Thanks to Daniel Hedlund.)
There would always be a garbage collection when evaluating I bsl N or I bsr N if I was a bignum.
If I is an integer and N a bignum, I bsl N will now cause the correct system_limit exception instead of bad_arith as in earlier releases.
If I is an integer and N a bignum, I bsr N will return either 0 or -1 depending on the sign of I instead of causing a bad_arith exception as in earlier releases.
Own Id: OTP-7764
Scheduler threads can now be bound to logical processors on newer Linux and Solaris systems. More systems will be supported in the future.
In some cases performance has increased drastically when binding schedulers. Schedulers are not bound by default, though. This since it might cause a performance degradation if multiple programs have bound to processors, e.g. multiple Erlang runtime systems. For more information see the documentation of erlang:system_flag/2.
In order to bind scheduler threads the CPU topology need to be known. On some newer Linux and Solaris systems the runtime system automatically detects the CPU topology. If the emulator isn't able to automatically detect the CPU topology, the CPU topology can be defined. For more information see the documentation of erlang:system_flag/2.
Own Id: OTP-7777
The compiler will refuse to a compile file where the module name in the file differs from the output file name.
When compiling using erlc, the current working directory will no be included in the code path (unless explicitly added using "-pa .").
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-7793
The BIFs atom_to_binary/2, binary_to_atom/2, and binary_to_existing_atom/2 have been added.
Own Id: OTP-7804
The amount of schedulers online can now be changed during operation. The amount of schedulers online defaults to the same amount as available logical processors. For more information see the documentation of erlang:system_flag/2 and erl.
Own Id: OTP-7811
The deprecated functions erlang:fault/1, erlang:fault/2, and file:rawopen/2 have been removed.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-7812
Erts internal dynamically allocated process and port specific data for rarely used data. This is used to reduce memory usage of processes and ports that do not use specific functionality. More functionality will be moved to process and port specific data in future releases.
Own Id: OTP-7818
New packet type http_bin for gen_tcp sockets and erlang:decode_packet. It works like http except that strings are returned as binaries instead of lists.
Own Id: OTP-7821
The obsolete wd_keeper program for embedded Solaris systems has been removed.
Own Id: OTP-7822
Nodes belonging to different independent clusters can now co-exist on the same host with the help of a new environment variable setting ERL_EPMD_PORT.
Own Id: OTP-7826
There are new functions erlang:min/2 and erlang:max/2 to calculate the minimum and maximum of two terms, respectively. Note that the functions are not auto-imported, so they need to be imported explicitly or the erlang prefix must be used when calling them.
Own Id: OTP-7841
The copyright notices have been updated.
Own Id: OTP-7851
Enhanced build environment for cross compilation to Tilera Tile architecture.
Support for native ethread atomics on Tilera Tile64/TilePro (Thanks to Tilera Corporation).
Own Id: OTP-7852
The escape sequences \x and \{ have been assigned new interpretations (they used to return the ASCII code for x and { respectively). One or more octal characters inside curly brackets after a leading backslash is from now on an alternative to the existing syntax \NNN, but can also be used for codes greater than 255. In a similar fashion, one or more hexadecimal characters can be put inside curly brackets after a leading \x. Furthermore, the escape sequences \xH and \xHH, where N is a hexadecimal character, can be used for codes less than 256.
NOTE: These new escape sequences are still considered experimental and may be changed in the R13B release.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-7855
The PCRE library's exported function names are now prefixed with erts_ in the erlang emulator to avoid clashes with dynamically loaded drivers.
Own Id: OTP-7861
A runtime system with SMP support will now be built by default on most platforms if a usable posix thread library or native windows threads are found.
For more information see the top README file.
Own Id: OTP-7872

Erts 5.6.5.1

Fixed Bugs and Malfunctions

A corrected bug in ETS for bag and duplicate_bag. A delete/2 or lookup_element/3 could miss objects in a fixed table if one or more objects with the same key had already been deleted.
Own Id: OTP-7665
A bug fixed for TCP sockets with option {packet,http}. An HTTP request with an absolute URI was returned with a corrupt path string. This bug did only exist in R12B-4 and R12B-5.
Own Id: OTP-7682 Aux Id: OTP-7647
Calling gen_tcp:send() from several processes on socket with option send_timeout could lead to much longer timeout than specified. The solution is a new socket option {send_timeout_close,true} that will do automatic close on timeout. Subsequent calls to send will then immediately fail due to the closed connection.
Own Id: OTP-7731 Aux Id: seq11161
A process being garbage collected via the garbage_collect/1 BIF or the check_process_code/2 BIF didn't handle message receive and resume correctly during the garbage collect. When this occurred, the process returned to the state it had before the garbage collect instead of entering the new state.
Own Id: OTP-7738

Erts 5.6.5

Fixed Bugs and Malfunctions

A bug in inet_drv concerning gen_tcp:connect has been corrected. A connect towards a non-open port through open firewalls could sometimes erroneously be successful. Any subsequent operation would fail, though.
Own Id: OTP-6542
Floating point arithmetic in drivers could cause a runtime system crash and/or unexpected results on runtime systems with floating point exceptions enabled. Floating point exceptions are disabled unless explicitly enabled or if hipe is enabled.
Own Id: OTP-7237
A bug when many sockets got signalled simultaneously causing the emulator to panic with the message "Inconsistent, why isn't io reported?" is now corrected.
Own Id: OTP-7420
Starting erl with option "-detached" now disconnects correctly from terminal session on Unix.
Own Id: OTP-7461
Mended gdb etp-commands for ETS access.
Own Id: OTP-7538
erlang:decode_packet/3 allows white space between HTTP header tag and colon according to RFC2616.
Own Id: OTP-7543
An emulator compiled for SCTP now starts even if the dynamic libraries are not present. The SCTP driver is then of course not loaded.
Own Id: OTP-7551
To build on Mac OS X, 10.3.0 or later is now required because of fixes for two problems:
There would be a resource leak when erl_ddl attempted to unload a driver. This problem has been corrected by using dlopen() (which works on all modern Unix-like platforms) instead of the Mac OS X specific API calls.
Signal handling in the run-time system for HiPE has been updated to work on later versions of Mac OS X than 10.2.x. Therefore, --enable-hipe now works on Mac OS X with Intel CPUs.
Thanks to Geoff Cant for the patches.
Own Id: OTP-7562
Corrected some information about the protocol between EPMD and Erlang nodes. (Thanks to Michael Regen.)
Own Id: OTP-7594
When using erlang:system_monitor(Pid,{long_gc,Time}), and the GC time exceeded 1 second, it sometimes erroneously showed up as about 4300 seconds. (This bug was corrected in R9C, but re-introduced in R12B.) (Thanks to Chris Newcombe.)
Own Id: OTP-7622 Aux Id: OTP-4903, seq8379

Improvements and New Features

The driver entry of a dynamically loaded driver is now copied when loaded which enables some internal optimizations. Note that drivers that modify the driver entry during execution will not work anymore. Such a miss-use of the driver interface is however not supported.
Own Id: OTP-6900
The split function is now added to the re library. Exceptions and errors from both run, replace and split are made more consistent.
Own Id: OTP-7514 Aux Id: OTP-7494
Fixed harmless compiler warnings when building the emulator and minor build changes in order to avoid unnecessary rebuilds.
Own Id: OTP-7530
There is now experimental support for loading of code from archive files. See the documentation of code, init, erl_prim_loaderand escript for more info.
The error handling of escripts has been improved.
An escript may now set explicit arguments to the emulator, such as -smp enabled.
An escript may now contain a precompiled beam file.
An escript may now contain an archive file containing one or more applications (experimental).
The internal module code_aux has been removed.
Own Id: OTP-7548 Aux Id: otp-6622
The reallocation functionality part of the ERTS internal memory allocators, now consider current block in combination with surrounding free blocks as an alternative location for a reallocation.
Own Id: OTP-7555
There could remain false references from a process to a module that has been called earlier, so that the process would be killed if the module was reloaded. (Thanks to Richard Carlsson.)
Also, the fix for this bug also made it possible to make stack backtraces (as returned from erlang:get_stacktrace/0 and other functions) more correct in that the immediate caller is always included in the stack backtrace (it could sometimes be missing).
Own Id: OTP-7559
Improved locking in IO-handling for better smp performance.
Own Id: OTP-7560
Improved BIF rescheduling functionality.
Own Id: OTP-7587
Loading a module compiled with Erlang/OTP R9C and calling module_info/0 in the module would crash the emulator. The emulator now refuses to load any module compiled with R9C or earlier. (Note: only trivial modules compiled with R10B or earlier could be loaded anyway.) (Thanks to Martin Kjellin.)
Own Id: OTP-7590

Erts 5.6.4.2

Fixed Bugs and Malfunctions

A process calling one of the following BIFs could under very rare conditions deadlock in the runtime system with SMP support: check_process_code/2, garbage_collect/1, process_info/[1,2], system_flag/2, and erlang:suspend_process/[1,2].
Own Id: OTP-7582
A couple of statistics variables were not managed in a thread safe manner in the runtime system with SMP support.
Own Id: OTP-7583
An extremely rare race condition when terminating a process could potentially cause a runtime system crash.
Own Id: OTP-7584
Under certain conditions and when using run_erl/to_erl, the terminal Erlang driver (ttsl_drv) could crash the emulator by doing a division by zero due to incorrect handling of terminals reporting a zero width. For terminals reporting zero width, the driver now fallbacks to a default width of 80 and a default height of 24 (vt100), as a fallback behaviour. This fixes the crashes and also makes output on "dumb" terminals much more readable.
Own Id: OTP-7592 Aux Id: seq11073

Erts 5.6.4.1

Improvements and New Features

A new erts_alloc parameter +M<S>rmbcmt (relative multiblock carrier move threshold) has been added. It determines when to force a moving realloc in a multiblock carrier when a block is shrunk. For more information see the erts_alloc(3) documentation.
Own Id: OTP-7540
The new option +d can be given to erl to suppress the crash dump generation if an internal error is detected. As a result, a more useful core dump is produced.
Own Id: OTP-7578 Aux Id: seq11052

Erts 5.6.4

Fixed Bugs and Malfunctions

Double backslashes in format string passed to the erts internal printf implementation produced erroneous results. No such format strings were passed to the erts internal printf implementation, i.e., the bug was therefore completely harmless. (Thanks to Perry Smith.)
Own Id: OTP-7408
Large files are now handled on Windows, where the filesystem supports it.
Own Id: OTP-7410
Bug fixed for {packet,http} when space follows http headers.
Own Id: OTP-7458
The trace option running could cause an emulator crash if the current function couldn't be determined.
Own Id: OTP-7484
Using 16#ffffFFFF as a timeout value in receive...after would often cause a timeout almost at once due to an 32-bit integer overflow. (Thanks to Serge Aleynikov and Matthias Lang.)
Own Id: OTP-7493
For the process that an escript runs in, the trap_exit process flag is now false instead of true (as in previous releases). Scripts that depend on the previous (counter-intuitive) behaviour might not work. (Thanks to Bengt Kleberg.)
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-7517
A bug in the string:to_integer/1 builtin made the emulator unstable. This is now corrected. (Thanks to Lev Walkin.)
Own Id: OTP-7526

Improvements and New Features

Performance for ETS intensive applications should now be better in the SMP emulator. Also, ETS table identifiers (as returned by ets:new/2) are now spread out in wider range than before (using 28 bits in a 32-bit emulator) to make sure that the table identifier for a deleted table will not be quickly re-used.
NOTE: Table identifiers can now be negative integers. Programs that (incorrectly) assume that table identifiers can only be positive integers might stop to work. (The type of a table identifier is intentionally not documented, and may change in a future release.)
Own Id: OTP-7348
New BIF erlang:decode_packet/3 that extracts a protocol packet from a binary. Similar to the socket option {packet, Type}. Also documented the socket packet type http and made it official. NOTE: The tuple format for http packets sent from an active socket has been changed in an incompatible way.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-7404
The source code for the documentation for some applications (erts, kernel, stdlib, and several others) are now included in the source tar ball. There is currently no Makefile support for building HTML files from the source (such support will be included in a future release).
Own Id: OTP-7406
A lot of frequently accessed memory counters (erts internal) have been removed. This since they hurt performance on the runtime system with SMP support. As a result erlang:memory/[0,1] will only deliver a result if all erts_alloc(3) allocators are enabled (default). The result delivered when all erts_alloc(3) allocators are enabled are both more accurate and less accurate than before. More memory than before are included in the result, but the different parts that are summed are not gathered atomically. A call to erlang:memory/[0,1] is much cheaper for the system than before. This since the information isn't gathered atomically anymore which was very expensive.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-7468
Pre-allocators used for, for example, timers, and messages have been rewritten to be scheduler specific. That is, different schedulers will now allocate from different pools which reduces lock contention.
Own Id: OTP-7470
On Mac OS X, file:sync/1 now guarantees that all filesystem buffers are written to the disk by using the fcntl() with F_FULLFSYNC option. Previously, file:sync/1 called fsync(), which only guaranteed that the data had been transferred to the disk drive. (Thanks to Jan Lehnardt.)
Own Id: OTP-7471
Termination of a process that takes a long time can now be preempted, i.e., the terminating process will be rescheduled for later continuation of termination so that other processes can execute. Termination of a process that owns many and/or large ets tables typically takes a long time.
Own Id: OTP-7477
A new trace option exiting has been added. The exiting trace is similar to the running trace, but for exiting processes. For more information see the erlang(3) documentation.
The erlang:trace/3 bif now doesn't block other scheduler threads if only one tracee is specified in the call to erlang:trace/3.
Own Id: OTP-7481
The re module is extended with repetitive matches (global option) and replacement function.
Own Id: OTP-7494 Aux Id: OTP-7181
In the section about binary construction, the reference manual now mentions what happens when an integer value does not fit into an integer segment of size N (namely, that the N least significant bits will be put into the binary and that the most significant bits will be silently discarded). (Thanks to Edwin Fine.)
Own Id: OTP-7506
Setting the {active,once} for a socket (using inets:setopts/2) is now specially optimized (because the {active,once} option is typically used much more frequently than other options).
Own Id: OTP-7520

Known Bugs and Problems

Floating point arithmetic in drivers can cause a runtime system crash and/or unexpected results on runtime systems with floating point exceptions enabled. Floating point exceptions are disabled unless explicitly enabled or if hipe is enabled.
Own Id: OTP-7237

Erts 5.6.3.3

Fixed Bugs and Malfunctions

Binary construction with an integer field of size 0 at the end of the constructed binary (and the size given in a variable), would cause a write of one byte outside the memory reserved for the binary, which in turn could cause an emulator crash.
Own Id: OTP-7422
A race condition in the dynamic driver implementation could cause an emulator crash. (Thanks to Paul Fisher)
Own Id: OTP-7464
Calls to erlang:system_info(allocated_areas) could cause the runtime system with SMP support to crash.
Own Id: OTP-7474
The env option to open_port() could cause the runtime system with SMP support to crash.
Own Id: OTP-7475

Improvements and New Features

Operations that needed to block other threads in the runtime system with SMP support unnecessarily waited for async threads to block. Most important the erlang:memory/[0,1] bif, code loading, and the erlang:trace/3 bif.
Own Id: OTP-7480

Erts 5.6.3.2

Fixed Bugs and Malfunctions

Calls to erlang:memory/[0,1] could cause the runtime system with SMP support to crash.
Own Id: OTP-7415

Erts 5.6.3.1

Fixed Bugs and Malfunctions

Doing local call trace on bit syntax matching code that has been optimized with delayed sub-binary creation could crash the emulator.
Own Id: OTP-7399 Aux Id: seq10978

Erts 5.6.3

Fixed Bugs and Malfunctions

Only one to_erl process at a time is allowed to connect to the same run_erl pipe. Prevents buggy behaviour when IO from several to_erl's get interleaved.
Own Id: OTP-5107
IPv6 name resolving has now been fixed to use getaddrinfo() patch (thoroughly reworked) courtesy of Love Hörnquist-Åstrand submitted by Fredrik Thulin. It also can use gethostname2() patch (also reworked) courtesy of Mikael Magnusson for debian submitted by Sergei Golovan.
Own Id: OTP-5382
Improved error handling in run_erl
Own Id: OTP-7252
A permanent fix for the deadlock issue temporarily fixed by OTP-7260.
- OTP-7260 - The runtime system with SMP support could under rare circumstances deadlock when a distribution channel was taken down while multiple simultaneous operations were performed on it.
Own Id: OTP-7267 Aux Id: OTP-7260
./configure has been improved to find 64-bit OpenSSL libraries.
Own Id: OTP-7270
A terminating process could under very rare circumstances trigger a bug which could crash the runtime system with SMP support.
Own Id: OTP-7272
SCTP_ADDR_CONFIRMED events are now handled by gen_sctp.
Own Id: OTP-7276
binary_to_term/1 would crash the emulator if the binary data contained an external fun with non-atom module and/or function. Corrected to generate a badarg exception.
Own Id: OTP-7281
On Mac OS 10.5 (Leopard), sending to socket which the other end closes could cause the emulator to consume 100% CPU time. (Thanks to Matthias Radestock.)
Own Id: OTP-7289
The vanilla driver used on Windows could crash the emulator and sometimes produced corrupt files. The vanilla driver is the driver that is used when one only pass a filename as first argument to open_port/2. NOTE: This use of open_port/2 is obsolete, and the documentation of this use has previously been removed. The functionality is only present for backward compatibility reasons and will eventually be removed.
Own Id: OTP-7301
Faulty matching in binaries larger than 512Mb on 64bit machines fixed.(On 32bit, the size limit for binaries is still 512Mb). Thanks to Edwin Fine and Per Gustafsson for finding fault and fix.
Own Id: OTP-7309
crypto:start() on Windows caused emulator to hang on error popup window if openssl DLL was not found. Windows error popups now suppressed.
Own Id: OTP-7325
Configuration option without-termcap can be used to disable the use of termcap libraries for terminal cursor control in the shell.
Own Id: OTP-7338
to_erl reports its terminal window size to run_erl in order to get output formatted accordingly
Own Id: OTP-7342
On Solaris, the compressed option for file operations did not work if the file descriptor happened to be greater than 255 (a problem with fopen() and friends in Solaris itself).
Own Id: OTP-7343 Aux Id: seq10949
A race condition in the runtime system with SMP support causing an erroneous removal of a newly created ets table has been fixed.
The race occurred when a process removed a table during termination simultaneously as another process removed the same table via ets:delete/1 and a third process created a table that accidentally got the same internal table index as the table being removed.
Own Id: OTP-7349
zlib:inflate failed when the size of the inflated data was an exact multiple of the internal buffer size (4000 bytes by default).
Own Id: OTP-7359
If the total number of allowed atoms is exceeded, there will now be a controlled termination of the emulator with a crash dump file. The emulator used to simply crash. (Thanks Howard Yeh and Thomas Lindgren.)
Own Id: OTP-7372
The break handler in werl on Windows could cause the emulator to hang or crash, that is now corrected.
Own Id: OTP-7394 Aux Id: seq10969
The configure script now tests for an serious optimization bug in gcc-4.3.0. If the bug is present, the configure script will abort (if this happens, the only way to build Erlang/OTP is to change to another version of gcc). (Thanks to Mikael Pettersson.)
Own Id: OTP-7397

Improvements and New Features

On Unix, the emulator now notices when the width of the terminal has changed. (Thanks to Matthew Dempsky and Patrick Mahoney.)
Own Id: OTP-7290
There is a new function init:stop/1 which can be used to shutdown the system cleanly AND generate a non-zero exit status or crash dump. (Thanks to Magnus Froberg.)
Own Id: OTP-7308
process_info(Pid, garbage_collection) now returns more information
Own Id: OTP-7311
The hide option for open_port/2 is now documented. (Thanks to Richard Carlsson.)
Own Id: OTP-7358

Known Bugs and Problems

Floating point arithmetic in drivers can cause a runtime system crash on runtime systems with floating point exceptions enabled. Floating point exceptions are disabled unless explicitly enabled or if hipe is enabled.
Own Id: OTP-7237

Erts 5.6.2

Fixed Bugs and Malfunctions

The maximum length of an atom of 255 characters is now strictly enforced. binary_to_term/1 will now fail with a badarg if an encoded term contains an atom longer than 255 characters. Atoms created by drivers will now be truncated to 255 characters if necessary. (Thanks to Matthew Dempsky.)
Own Id: OTP-7147
A bug in "bignum handling" on some 64bit architectures could cause rem and div operations on large numbers to hang indefinitely. Rem operations involving the smallest negative number representable in 28 bits or 60 bits could also cause access violation and emulator crash. Both errors are corrected.
Own Id: OTP-7177
When doing the initial garbage collection after waking a hibernated process, a fullsweep garbage collection was unnecessarily triggered.
Own Id: OTP-7212
The beta testing module gen_sctp now supports active mode as stated in the documentation. Active mode is still rather untested, and there are some issues about what should be the right semantics for gen_sctp:connect/5. In particular: should it be blocking or non-blocking or choosable. There is a high probability it will change semantics in a (near) future patch.
Try it, give comments and send in bug reports!
Own Id: OTP-7225
Invalid arguments to ets:update_counter/3 were not handled correctly. A tuple position (Pos) less than 1 caused the element directly following the key to be updated (as if no position at all had been specified). All invalid values for Pos will now fail with badarg.
Own Id: OTP-7226
The runtime system with SMP support could under rare circumstances deadlock when a distribution channel was taken down while multiple simultaneous operations were performed on it.
Own Id: OTP-7260

Improvements and New Features

More checksum/hash algorithms from the zlib library are now available as built in functions (like md5 hashes has been for a long time).
Own Id: OTP-7128
Minor improvements in the garbage collector.
Own Id: OTP-7139 Aux Id: OTP-7132
The switch "-detached" to the windows werl program now can create an erlang virtual machine without any main window and without a temporary console showing.
Own Id: OTP-7142
erlang:system_info/1 now accepts the logical_processors, and debug_compiled arguments. For more info see the, erlang documentation.
The scale factor returned by test_server:timetrap_scale_factor/0 is now also effected if the emulator uses a larger amount of scheduler threads than the amount of logical processors on the system.
Own Id: OTP-7175
A new BIF ets:update_element/3. To update individual elements within an ets-tuple, without having to read, update and write back the entire tuple.
Own Id: OTP-7200
A process executing the processes/0 BIF can now be preempted by other processes during its execution. This in order to disturb the rest of the system as little as possible. The returned result is, of course, still a consistent snapshot of existing processes at a time during the call to processes/0.
The documentation of the processes/0 BIF and the is_process_alive/1 BIF have been updated in order to clarify the difference between an existing process and a process that is alive.
Own Id: OTP-7213

Erts 5.6.1.1

Fixed Bugs and Malfunctions

Not enough parameters were passed when sending an error report in erl_check_io.c (Thanks to Matthew Dempsky).
Own Id: OTP-7176
In rare circumstances, complex binary matching code could cause the emulator to crash or not match when it should. (Thanks to Rory Byrne.)
Own Id: OTP-7198

Improvements and New Features

The {allocator_sizes, Alloc} and alloc_util_allocators arguments are now accepted by erlang:system_info/1. For more information see the erlang documentation.
Own Id: OTP-7167
The finishing reallocation of the heap block when hibernating a process is now always moving the heap block since it drastically reduces memory fragmentation when hibernating large amounts of processes.
Own Id: OTP-7187

Erts 5.6.1

Fixed Bugs and Malfunctions

The SMP emulator on sparc64 erroneously used the sparc32 atomic and the sparc32 spinlock implementations which caused it to crash.
Own Id: OTP-7006
Call tracing the new guard BIFs byte_size, bit_size, or tuple_size and the loading a module that uses one of those functions, could cause the emulator to terminate.
Own Id: OTP-7008
configuring --enable-darwin-universal or --enable-darwin-64bit on MacOSX could result in a non optimized emulator. Top level configure script now corrected.
Own Id: OTP-7014
configuring --with-gd did not produce correct include flags for percept.
Own Id: OTP-7015
Environment variables weren't handled in thread safe manner in the runtime system with SMP support on Windows.
erl_drv_putenv(), and erl_drv_getenv() has been introduced for use in drivers. Do not use putenv(), or getenv() directly in drivers. For more information see the erl_driver documentation.
Own Id: OTP-7035
HIPE: Corrected the choice of interface to the send/3 and setnode/3 BIFs for native-compiled code. Using the incorrect interface could, in unusual circumstances, lead to random runtime errors.
Own Id: OTP-7067
Garbage collections could become extremely slow when there were many keys in the process dictionary. (Thanks to Fredrik Svahn.)
Own Id: OTP-7068
The duplicate documentation directory in the windows installation is removed.
Own Id: OTP-7070
Documentation bugfixes and clarifications.
(Thanks to Joern (opendev@gmail.com), Matthias Lang, and Richard Carlsson.)
Own Id: OTP-7079
The runtime system with SMP support not using the native atomic integer implementation part of OTP could deadlock when run on a system with more than one logical processor. That is, only the runtime system with SMP support on other hardware platforms than x86, x86_64, sparc32, and powerpc32 were effected by this bug.
Own Id: OTP-7080
The break handling code (run when Ctrl-C is hit) could could potentially deadlock the runtime system with SMP support.
Own Id: OTP-7104
The sctp driver has been updated to work against newer lksctp packages e.g 1.0.7 that uses the API spelling change adaption -> adaptation. Older lksctp (1.0.6) still work. The erlang API in gen_sctp.erl and inet_sctp.hrl now spells 'adaptation' regardless of the underlying C API.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-7120
A bug in erlang:phash2/1 on 64-bit platforms has been fixed. (Thanks to Scott Lystig Fritchie.)
Own Id: OTP-7127
The emulator could under rare circumstances crash while garbage collecting.
Own Id: OTP-7132

Improvements and New Features

The documentation has been updated so as to reflect the last updates of the Erlang shell as well as the minor modifications of the control sequence p of the io_lib module.
Superfluous empty lines have been removed from code examples and from Erlang shell examples.
Own Id: OTP-6944 Aux Id: OTP-6554, OTP-6911
Bit syntax construction with a small integer in a non-byte aligned field wider than the CPU's word size could cause garbage bits in the beginning of the field.
Own Id: OTP-7085
All Windows versions older than Windows 2000 are now not supported by the Erlang runtime system. This since there was a need for usage of features introduced in Windows 2000.
Own Id: OTP-7086
Memory management improvements especially for the runtime system with SMP support:
- The runtime system with SMP support can now use multiple, thread specific instances of most memory allocators. This improves performance since it reduces lock contention in the memory allocators. It may however increase memory usage for some applications. The runtime system with SMP support will by default enable this feature on most allocators. The amount of instances used can be configured.
- driver_alloc(), driver_realloc(), and driver_free() now use their own erts specific memory allocator instead of the default malloc() implementation on the system.
- The default configuration of some allocators have been changed to fit applications that use much memory better.
- Some new erts_alloc configuration parameters have been added.
- erts_alloc_config has been modified to be able to create configurations suitable for multiple instances of allocators.
- The returned value from erlang:system_info({allocator, Alloc}) has been changed. This since an allocator may now run in multiple instances.
If you for some reason want the memory allocators to be configured as before, you can pass the +Mea r11b command-line argument to erl.
For more information see the erts_alloc(3), the m:erts_alloc_config, and the erlang documentation.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-7100
On Unix, denormalized floating point numbers could not be created using list_to_float/1 or binary_to_term/1. (Thanks to Matthew Dempsky.)
Own Id: OTP-7122
Native atomic integers and spin-locks are now also available for the runtime system with SMP support on sparc64.
Own Id: OTP-7130
FP exceptions support for sparc64 userspace on Linux has been added. Note that FP exception support is now turned off by default, so to actually enable it you need to do './configure --enable-fp-exceptions'.
Own Id: OTP-7131

Erts 5.6

Fixed Bugs and Malfunctions

A bug for raw files when reading 0 bytes returning 'eof' instead of empty data has been corrected.
Own Id: OTP-6291 Aux Id: OTP-6967
All exported functions in gzio.c have now been renamed to avoid conflict with drivers that are indirectly linked with an external zlib library.
Own Id: OTP-6816 Aux Id: OTP-6591
On the 64-bit Erlang emulator, bit syntax construction with integers containing more than 60 bits ("big numbers") into fields with more than 60 bits could produce incorrect results.
Own Id: OTP-6833
When the runtime system failed to allocate memory for binaries, it could dead lock while writing the erl_crash.dump.
Own Id: OTP-6848
The runtime system with SMP support could deadlock if a process called the erlang:suspend_process(Pid) BIF or the erlang:garbage_collect(Pid) BIF while the process identified by Pid was currently running and the process calling the BIFs was terminated during the call to the BIFs.
Processes suspending each other via the erlang:suspend_process/1 BIF or garbage collecting each other via the erlang:garbage_collect/1 BIF could deadlock each other when the runtime system with SMP support was used.
Own Id: OTP-6920
dbg could leave traced processes in a suspended state if the tracer process was killed with exit reason kill.
erlang:suspend_process/2 has been introduced which accepts an option list as second argument. For more information see the erlang documentation.
Processes suspended via erlang:suspend_process/[1,2] will now be automatically resumed if the process that called erlang:suspend_process/[1,2] terminates.
Processes could previously be suspended by one process and resumed by another unless someone was tracing the suspendee. This is not possible anymore. The process resuming a process has to be the one that suspended it.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-6946
file:write_file/3, file:write/2 and file:read/2 could crash (contrary to documentation) for odd enough file system problems, e.g write to full file system. This bug has now been corrected.
In this process the file module has been rewritten to produce better error codes. Posix error codes now originate from the OS file system calls or are generated only for very similar causes (for example 'enomem' is generated if a memory allocation fails, and 'einval' is generated if the file handle in Erlang is a file handle but currently invalid).
More Erlang-ish error codes are now generated. For example {error,badarg} is now returned from file:close/1 if the argument is not of a file handle type. See file(3).
The possibility to write a single byte using file:write/2 instead of a list or binary of one byte, contradictory to the documentation, has been removed.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-6967 Aux Id: OTP-6597 OTP-6291
Monitor messages produced by the system monitor functionality, and garbage collect trace messages could contain erroneous heap and/or stack sizes when the actual heaps and/or stacks were huge.
As of erts version 5.6 the large_heap option to erlang:system_monitor/[1,2] has been modified. The monitor message is sent if the sum of the sizes of all memory blocks allocated for all heap generations is equal to or larger than the specified size. Previously the monitor message was sent if the memory block allocated for the youngest generation was equal to or larger than the specified size.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-6974 Aux Id: seq10796
inet:getopts/2 returned random values on Windows Vista.
Own Id: OTP-7003

Improvements and New Features

The emulator internal process lock implementation has been rewritten and optimized. A slight risk of starvation existed in the previous implementation. This risk has also been eliminated in the new implementation.
Own Id: OTP-6500
Bitstrings (bit-level) binaries and binary comprehensions are now part of the language. See the Reference Manual.
Own Id: OTP-6558
The windows version of erlang now has SMP support. The SMP emulator is run by default on machines which shows more than one virtual or physical processor.
Own Id: OTP-6560 Aux Id: OTP-6925
The details of the compressed term format has been documented in erl_ext_dist.txt. (Thanks to Daniel Goertzen.)
Own Id: OTP-6755
The runtime system with SMP support is now started by default if more than one logical processor are detected. For more information, see the erl(3) documentation.
Own Id: OTP-6756
The external format for Erlang terms and the distribution protocol are now documented in ERTS User's Guide.
Own Id: OTP-6779
New BIF's erlang:system_profile/1 and erlang:system_profile/2. These BIF's controls concurrency profiling options for processes, ports and schedulers.
Own Id: OTP-6783 Aux Id: OTP-6285
The ErlDrvTermData term types used by driver_output_term() and driver_send_term() have been extended with the term types ERL_DRV_BUF2BINARY, ERL_DRV_EXT2TERM, and ERL_DRV_UINT. ERL_DRV_BUF2BINARY is used for passing and creating a binary, ERL_DRV_EXT2TERM is used for passing terms encoded with the external term format, and ERL_DRV_UINT is used for passing unsigned integers.
Also the data types ErlDrvUInt and ErlDrvSInt have been added which makes it more obvious how arguments to term types are interpreted with regards to width and signedness.
The incorrect data types ErlDriverTerm, ErlDriverBinary, and ErlDriverPort in the erl_driver(3) documentation have been replaced with the correct data types ErlDrvTermData, ErlDrvBinary, and ErlDrvPort.
For more information see the erl_driver(3) documentation.
Own Id: OTP-6823
Miscellaneous improvements of the erts internal thread library.
It now support optimized atomic operations and spin-locks on windows.
Fall-backs based on mutexes and/or spin-locks for missing optimized atomic operations, spin-locks, or rwlocks has been implemented. This makes it possible to compile the runtime system with SMP support on a lot more platforms.
Default stack size on OpenBSD has been increased to 256 kilo-words.
Own Id: OTP-6831 Aux Id: OTP-6560
Many bit syntax operations, both construction and matching, are faster. For further information, see the Efficiency Guide.
Own Id: OTP-6838
Literal lists, tuples, and binaries are no longer constructed at run-time as they used to be, but are stored in a per-module constant pool. Literals that are used more than once are stored only once.
This is not a change to the language, only in the details of its implementation. Therefore, the implications of this change is described in the Efficiency Guide.
Example 1: In the expression element(BitNum-1, {1,2,4,8,16,32,64,128}), the tuple used to be constructed every time the expression was executed, which could be detrimental to performance in two ways if the expression was executed in a loop: the time to build the tuple itself and the time spent in garbage collections because the heap filled up with garbage faster.
Example 2: Literal strings, such as "abc", used to be stored in the compiled code compactly as a byte string and expanded to a list at run-time. Now all strings will be stored expanded to lists (such as [$a,$b,$c]) in the constant pool. That means that the string will be faster to use at run-time, but that it will require more space even when not used. If space is an issue, you might want to use binary literals (that is, <<"abc">>) instead of string literals for infrequently used long strings (such as error messages).
Own Id: OTP-6850
The Erlang driver API has been extended with a portable POSIX thread like API for multi-threading. The Erlang driver thread API provides:
- Threads
- Mutexes
- Condition variables
- Read/Write locks
- Thread specific data
For more information see the erl_driver(3) documentation.
Own Id: OTP-6857
Recursive calls now usually consume less stack than in R11B. See the Efficiency Guide.
Own Id: OTP-6862 Aux Id: seq10746
The deprecated BIFs erlang:old_binary_to_term/1 and erlang:info/1 have been removed.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-6876
Calls to driver call-backs triggered by external events are now scheduled and interleaved with execution of Erlang processes also on the runtime system without SMP support.
Own Id: OTP-6878
Faster arithmetic of integers of more than 27 bits signed (or 60 bits signed on an 64-bit CPU), and also faster integer multiplication. (Thanks to Tony Rogvall.)
Own Id: OTP-6891
Significant improvements of the process_info BIFs:
- process_info/2 can now be called with a list of items as second argument in order to atomically retrieve information about multiple items.
- process_info/[1,2] has been optimized in the runtime system with SMP support. The whole scheduler could previously be blocked for a significant period of time in process_info/[1,2] waiting for a lock on the process being inspected. The Erlang process calling process_info/[1,2] can still be blocked for a significant period of time waiting for the lock, but the scheduler will now be able to run other processes while the process calling process_info/[1,2] waits for the lock.
- process_info/2 now accept a few more items than before.
- The documentation of process_info/[1,2] has been improved.
For more information see the erlang documentation.
Own Id: OTP-6899
open_port({}, []) could crash the emulator. (Thanks to Matthew Dempsky.)
Own Id: OTP-6901
Two new guard BIFs have been introduced as a recommended replacement for size/1. (The size/1 BIF will be removed no earlier than in R14B.) The BIFs are tuple_size/1 to calculate the size of a tuple and byte_size/1 to calculate the number of bytes needed for the contents of the binary or bitstring (rounded up to the nearest number of bytes if necessary).
There is also a new bit_size/1 BIF that returns the exact number of bits that a binary or bitstring contains.
Own Id: OTP-6902
The ets:fixtable/2 function, which has been deprecated for several releases, has been removed.
The ets:info/1 function has been reimplemented as a BIF, which guarantees that information returned is consistent.
The ets:info/2 function now fails with reason badarg if the second argument is invalid. (Dialyzer can be used to find buggy code where the second argument is misspelled.)
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-6906
As the linux kernel may generate a minor fault when tracing with CPU timestamps, and there exists no patch to the Linux kernel that fixes the problem, cpu timestamps are disabled on Linux for now.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-6922
The functions io:columns/0, io:columns/1, io:rows/0 and io:rows/1 are added to allow the user to get information about the terminal geometry. The shell takes some advantage of this when formatting output. For regular files and other io-devices where height and width are not applicable, the functions return {error,enotsup}.
Potential incompatibility: If one has written a custom io-handler, the handler has to either return an error or take care of io-requests regarding terminal height and width. Usually that is no problem as io-handlers, as a rule of thumb, should give an error reply when receiving unknown io-requests, instead of crashing.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-6933
driver_caller() can now also be used from the start callback of a driver.
Own Id: OTP-6951
The emulator can now be compiled for 64bit intel, as well as a 32bit universal binary on darwin/MacOSX 10.4 and 10.5.
Own Id: OTP-6961
If open_port fails because all available ports are already in use, it will now throw a system_limit exception instead of an enfile exception. (enfile might still be thrown if the operating system would return ENFILE.)
Own Id: OTP-6968
The spawn_monitor/1 and spawn_monitor/3 BIFs are now auto-imported (i.e. they no longer need an erlang: prefix).
Own Id: OTP-6975
On Windows, the werl window now handles resize, so that the whole window can be utilized. Text selection is also updated to be line oriented instead of rectangle oriented as in earlier versions.
Own Id: OTP-6994 Aux Id: OTP-6933
Kqueue support (kernel-poll) has been enabled on FreeBSD. The problem with kqueue not detecting writes on a pipe on FreeBSD was actually not a kqueue issue, but a writev on pipes issue. Neither poll(), nor select() detected the write when the bug hit. NetBSD and DragonFlyBSD probably have or have had the same bug. This bug should have been fixed in FreeBSD 6.3 and FreeBSD 7.0 thanks to Jean-Sebastien Pedron.
Own Id: OTP-7001

Erts 5.5.5.5

Fixed Bugs and Malfunctions

Hanging writes on temporarily unavailable NFS filesystems could cause the execution of (not file related) erlang code to get blocked even though I/O threads were used. This is now corrected.
Own Id: OTP-6907 Aux Id: seq10771

Erts 5.5.5.4

Fixed Bugs and Malfunctions

Data passed to a driver via erlang:port_call could be corrupted when the runtime system with SMP support was used. (Thanks to YAMASHINA Hio.)
Own Id: OTP-6879
In the SMP emulator, if several processes called ets:update_counter/3 (even for different tables) when the counter values exceeded 27 bits, the counter values could be corrupted or the emulator could crash.
Own Id: OTP-6880 Aux Id: seq10760

Erts 5.5.5.3

Fixed Bugs and Malfunctions

Creating a named table using ets:new/2 or renaming a named table using ets:rename/2 could in rare circumstances succeed, meaning that there would be two or more tables with the same name. Now such call will fail with a badarg exception as it is supposed to do.
ets:delete/1 used on a named table now removes the name immediately so that a new table with the same name can be created.
Turning on call trace on the internal BIF that implements ets:delete/1 would crash the emulator.
SMP emulator only: Using ets:rename/2 on a table that ets:safe_fixtable/2 has been used on could cause an emulator crash or undefined behaviour because of a missing lock.
Own Id: OTP-6872 Aux Id: seq10756, seq10757

Erts 5.5.5.2

Known Bugs and Problems

ets:select/3 on ordered_set and with a chunksize a multiple of 1000 gave all elements instead of just 1000. Also ets:slot/2 on ordered set could give unexpected results on SMP emulator. Both problems are corrected.
Own Id: OTP-6842

Erts 5.5.5.1

Fixed Bugs and Malfunctions

All exported functions in gzio.c have now been renamed to avoid conflict with drivers that are indirectly linked with an external zlib library.
Own Id: OTP-6816 Aux Id: OTP-6591
Calling binary_to_term/1 with certain invalid binaries would crash the emulator.
Own Id: OTP-6817

Improvements and New Features

Restored speed of bit-syntax matching of 32 bits integers.
Own Id: OTP-6789 Aux Id: seq10688

Erts 5.5.5

Fixed Bugs and Malfunctions

The functions in gzio.c have been renamed to avoid conflict with drivers that indirectly linked with an external zlib library.
Own Id: OTP-6591
The emulator without SMP support dumped core if an async-thread finished a job after the emulator had begun writing an erl_crash.dump.
Own Id: OTP-6685
In bit syntax matching, integer fields with greater size than 16Mb would fail to match. (Thanks to Bertil Karlsson and Francesco Pierfederici.)
Matching out a 32-bit integer not aligned on a byte boundary from a binary could cause an heap overflow (and subsequent termination of the emulator).
A module that contained bit syntax construction with a literal field size greater than 16Mb would fail to load.
Several other similar bugs having to do with huge field sizes were eliminated.
Attempting to construct a binary longer than 536870911 bytes will now fail with a system_limit exception (rather than fail in mysterious ways or construct an binary with incorrect contents). Similarly, attempting to match a binary longer than 536870911 bytes will now fail (instead of producing an incorrect result). This limitation has been documented in the Efficiency Guide. (The limit is in the 32-bit emulator; use the 64-bit emulator if you need to handle larger binaries than 536870911.)
Own Id: OTP-6686
Bugs in rem and div of very large numbers are corrected.
Own Id: OTP-6692
erlang:system_info({allocator, Alloc}) didn't allocate enough heap when a bignum was part of the result which could cause an emulator crash.
Own Id: OTP-6693
It was previously not possible to pass erts_alloc the same configuration via the command-line, as used by default.
A +M* command-line argument that configure a size of some sort can now be passed a value that equals the size of the address space. The value used, in this case, will be "the size of the address space" - 1.
Own Id: OTP-6699
SysIOVec* driver_peekq(ErlDrvPort port, int *vlen) did not update *vlen if port was invalid. *vlen is now set to -1 if the port is invalid.
The efile driver expects *vlen to be updated also when the port is invalid. This situation occurs seldom, but when the runtime system has async-threads enabled and ports are killed it can. When it occurred the runtime system crashed.
Own Id: OTP-6729

Improvements and New Features

For scripts written using escript, there is a new function escript:script_name/0, which can be used to retrieve the pathame of the script. The documentation has been clarified regarding pre-defined macros such as ?MODULE and the module name.
Own Id: OTP-6593
The section Guards in the chapter The Abstract Format of the ERTS User's Guide has been updated.
Own Id: OTP-6600
Corrected protocol layer flue for socket options SO_LINGER, SO_SNDBUF and SO_RCVBUF, for SCTP.
Own Id: OTP-6625 Aux Id: OTP-6336
The behaviour of the inet option {active,once} on peer close is improved and documented.
Own Id: OTP-6681
The inet option send_timeout for connection oriented sockets is added to allow for timeouts in communicating send requests to the underlying TCP stack.
Own Id: OTP-6684 Aux Id: seq10637 OTP-6681
The command line flag -args_file FileName, and the environment variables ERL_AFLAGS, and ERL_ZFLAGS for the erl command have been added. For more information see the erl documentation.
Own Id: OTP-6697
The is_constant/1 type test has been deprecated. is_constant/1 is improperly named and almost entirely undocumented.
Own Id: OTP-6731

Erts 5.5.4.3

Fixed Bugs and Malfunctions

process_flag(trap_exit, Bad) where Bad was a term not equal to true or false, didn't fail with badarg as it should; instead, the failure was silently ignored. This bug was introduced in erts-5.5.2.
Own Id: OTP-6627 Aux Id: OTP-6160
The minimum and default stack size for async-threads has been increased to 16 kilowords. This since the previous minimum and default stack size of 8 kilowords proved to be too small (introduced in erts-5.5.4.2).
Own Id: OTP-6628 Aux Id: OTP-6580, Seq10633

Improvements and New Features

process_flag/2 accepts the new flag sensitive.
Own Id: OTP-6592 Aux Id: seq10555

Erts 5.5.4.2

Fixed Bugs and Malfunctions

When a port steals control over a file descriptor from another port, the stealing port tests if the other port is alive. This in order to be able to give an accurate error message. In the runtime system with SMP support, this test was done without appropriate locks held. This could in worst case lead to an erroneous error message; therefore, this bug is to be considered harmless.
Own Id: OTP-6602

Improvements and New Features

The default stack size for threads in the async-thread pool has been shrunk to 8 kilowords, i.e., 32 KB on 32-bit architectures. This small default size has been chosen since the amount of async-threads might be quite large. The default stack size is enough for drivers delivered with Erlang/OTP, but might not be sufficiently large for other dynamically linked in drivers that use the driver_async() functionality. A suggested stack size for threads in the async-thread pool can be configured via the +a command line argument of erl.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-6580

Erts 5.5.4.1

Fixed Bugs and Malfunctions

Setting the time on the system while using heart on a linux machine where the emulator was built with clock_gettime support (default from Linux 2.6/erts-5.5.4 and upwards), could make the heart command fire. This was due to bug in the heart executable which is now corrected.
Own Id: OTP-6598 Aux Id: seq10614

Erts 5.5.4

Fixed Bugs and Malfunctions

Corrected misspelling of '-pz' in the help text for erlc. (Thanks to Ulf Wiger.)
Own Id: OTP-6433
The MD5 calculation of a BEAM file done by code:module_md5/1, beam_lib:md5/1, and by the compiler for the default value of the vsn attribute have all been changed so that its result will be the same on all platforms; modules containing funs could get different MD5s on different platforms.
Own Id: OTP-6459
The emulator could dump core while writing an erl_crash.dump file if there were funs with a large terms in its environment. Since there is no way to inspect a fun's environment in the crashdump_viewer application anyway, a variables in the environment are now set to [] before dumping the fun. (Thanks to Jean-Sebastien Pedron.)
Own Id: OTP-6504
{Port, {exit_status, S}} messages from ports opened with the exit_status option could under rare circumstances be delayed. This bug was present on Erlang runtime systems without SMP support on all unix operating systems other than SunOS.
Own Id: OTP-6528
A bug in linuxthreads could cause the emulator to dump core when dlerror() was called before the first call to dlopen(). As a workaround the emulator always makes a call to dlopen() on initialization when linuxthreads is used as thread library.
Own Id: OTP-6530
file:sync/1 did not do anything on Windows. Now it calls the system function for flushing buffers (FlushFileBuffers()). (Thanks to Matthew Sackman.)
Own Id: OTP-6531
open_port/2 could on the runtime system with SMP support fail with the wrong exit reason when a port couldn't be created. When this happened the exit reason was typically eintr, or ebusy instead of eagain.
Own Id: OTP-6536
The file driver (efile_drv) did not flush data written using the option 'delayed_write' after the set timeout time, rather at the next file operation. This bug has now been corrected.
Own Id: OTP-6538

Improvements and New Features

An interface towards the SCTP Socket API Extensions has been implemented.It is an Open Source patch courtesy of Serge Aleynikov and Leonid Timochouk. The Erlang code parts has been adapted by the OTP team, changing the Erlang API somewhat.
The Erlang interface consists of the module gen_sctp and an include file -include_lib("kernel/include/inet_sctp.hrl"). for option record definitions. The gen_sctp module is documented.
The delivered Open Source patch, before the OTP team rewrites, was written according to http://tools.ietf.org/html/draft-ietf-tsvwg-sctpsocket-13 and was claimed to work fine, tested on Linux Fedora Core 5.0 (kernel 2.6.15-2054 or later) and on Solaris 10 and 11. The OTP team rewrites used the same standard document but might have accidentally broken some functionality. If so it will soon be patched to working state. The tricky parts in C and the general design has essentially not changed. During the rewrites the code was hand tested on SuSE Linux Enterprise Server 10, and briefly on Solaris 10. Feedbach on code and docs is very much appreciated.
The SCTP interface is in beta state. It has only been hand tested and has no automatic test suites in OPT meaning everything is most certainly not tested. Socket active mode is broken. IPv6 is not tested. The documentation has been reworked due to the API changes, but has not been proofread after this.
Thank you from the OTP team to Serge Aleynikov and Leonid Timochouk for a valuable contribution. We hope we have not messed it up too much.
Own Id: OTP-6336
A {minor_version,Version} option is now recognized by term_to_binary/2. {minor_version,1} will cause floats to be encoded in an exact and more space-efficient way compared to the previous encoding.
Own Id: OTP-6434
There is a new escript program that can be used for writing scripts in Erlang. Erlang scripts don't need to be compiled and any arguments can be passed to them without risk that they are interpreted by the Erlang system.
Own Id: OTP-6505
Setting and getting socket options in a "raw" fashion is now allowed. Using this feature will inevitably produce non portable code, but will allow setting ang getting arbitrary uncommon options on TCP stacks that do have them.
Own Id: OTP-6519
Miscellaneous signal handling improvements on the Erlang runtime system with SMP support.
The fallback implementation of spin locks and atomic operations are now implemented using pthread spin locks when pthread spin locks are found on the system.
The Erlang runtime system with SMP support can now run on Linux systems that has Linuxthreads instead of NPTL (Native POSIX Thread Library). Note that the SMP support hasn't been as thoroughly tested with Linuxthreads as with NPTL. A runtime system with SMP support will therefore not be built by default on Linux when NPTL isn't found. In order to force a build of the runtime system with SMP support, pass --enable-smp-support to configure when building OTP.
Own Id: OTP-6525

Erts 5.5.3.1

Fixed Bugs and Malfunctions

erlang:system_flag(multi_scheduling, block) could cause the emulator with SMP support to deadlock.
Own Id: OTP-6431 Aux Id: OTP-6403
The runtime system with SMP support failed to call the driver timeout callback of ports in state closing. This could cause ports to fail flushing their I/O queues.
Own Id: OTP-6432
The {Port, closed} message from a closed port could arrive at the port owner before Port had been removed from the result of erlang:ports/0 in the runtime system with SMP support.
Own Id: OTP-6437
The async id of async jobs created via driver_async wasn't created in a thread safe manner in the runtime system with SMP support. This could in worst case cause driver_async_cancel() to cancel another async job than intended.
Own Id: OTP-6438
Under rare circumstances a terminating connection between two nodes could cause an instantaneous reconnect between the two nodes to fail on the runtime system with SMP support.
Own Id: OTP-6447
In the documentation of the driver entry field extended_marker of erts version 5.5.3 (driver_entry(3)), the following is stated: "The following fields are ignored if this field is equal to 0". This is a documentation bug and has been changed to: "If this field is equal to 0, all the fields following this field also have to be 0, or NULL in case it is a pointer field".
The runtime check for detection of old incompatible drivers made when loading drivers has been improved. The emulator can, however, not make sure that a driver that doesn't use the extended driver interface isn't incompatible. Therefore, when loading a driver that doesn't use the extended driver interface, there is a risk that it will be loaded also when the driver is incompatible. When the driver use the extended driver interface, the emulator can verify that it isn't of an incompatible driver version. You are therefore advised to use the extended driver interface.
For more information see the erl_driver(3) and driver_entry(3) documentation.
Own Id: OTP-6452 Aux Id: OTP-6330
When terminating ports on the runtime system with SMP support, removal of links to processes was done without locking the link lock on processes. This could cause an emulator crash.
Own Id: OTP-6475
The emulator with SMP support could crash when a port flushed its I/O queue by calling driver_async() from the timeout driver callback.
Own Id: OTP-6479
Large exit reasons could under rare circumstances cause the runtime system with SMP support to crash.
Own Id: OTP-6521

Improvements and New Features

Faster system calls for keeping the time accurate are used on newer Linux kernels, which can result in a significant speed-up of the emulator on those systems.
Own Id: OTP-6430
Added number of async threads and number of scheduler threads to the system information that can be retrieved via driver_system_info(). For more information see the erl_driver(3) documentation.
Own Id: OTP-6440
When SIGUSR1 is received by the runtime system with SMP support, the erl_crash.dump is now written by a special thread, instead of as before directly from the signal handler.
Own Id: OTP-6465
term_to_binary/2 with compression is now faster.
term_to_binary/2 now accepts the option '{compressed,Level}' for specifying the compression level. Level must be in the range 0 (no compression) through 9 (highest compression level). Default is 6.
Future compatibility bugfix: binary_to_term/1 did not handle the Uniq and Index fields correctly.
Own Id: OTP-6494
Removed unnecessary reallocation when initializing kernel-poll set.
Own Id: OTP-6516

Erts 5.5.3

Fixed Bugs and Malfunctions

Node and fun table entries could under rare circumstances be deallocated multiple times on the emulator with SMP support.
Own Id: OTP-6369
epoll_wait() can repeat entries for the same file descriptor in the result array. This could cause the ready_input, ready_output, or event callbacks of a driver to unintentionally be called multiple times. We have only noted repeated entries when an error condition has occurred on the file descriptor. In this case, the repeated entries should normally not be a problem for the driver since it should detect the error and de-select the file descriptor. Therefore this bug should be considered harmless. The emulator now coalesce repeated entries into one.
You are only affected by this bug if you are using erts-5.5.2.* and the kernel-poll feature on linux.
Own Id: OTP-6376 Aux Id: OTP-6222
If a process that was waiting in gen_tcp:accept/1 was killed, calling gen_tcp:accept/1 again on the same listen socket would fail with '{error,einval}'.
Own Id: OTP-6381 Aux Id: seq10535
The emulator failed to start on Solaris 10 when kernel-poll support was enabled and the maximum number of filedescriptors configured was less than or equal to 256.
Own Id: OTP-6384 Aux Id: OTP-6222
The R10B compiler could generate unsafe bs_save/bs_restore instructions that could cause memory corruption. (The R11B compiler does not have that problem.) The erlang emulator will now refuse to load R10B-compiled modules that contain such unsafe bs_save/bs_restore instructions. In addition, the beam_validator module in the compiler will also reject such instructions (in case it is used to validate R10B code). (Thanks to Matthew Reilly.)
Own Id: OTP-6386
Process and port timers could fail to work properly on the runtime system with SMP support. Many thanks to Dmitriy Kargapolov and Serge Aleynikov who tracked down this bug.
Own Id: OTP-6387
Bit syntax code compiled by an R10B compiler that matched out a floating point number would not properly check that the floating point number was valid; if the float was, for instance, NaN the emulator could crash.
Own Id: OTP-6395
statistics(runtime) on Windows used to return the elapsed system time for the process, instead of the user time. Corrected. (Thanks to Robert Virding.)
Own Id: OTP-6407
A loadable driver (loaded by erl_ddll) which used driver_async() would cause the emulator to crash. (Thanks to Dmitriy Kargapolov.)
Own Id: OTP-6410
Under rare circumstances the emulator on unix platforms could fail to terminate the Erlang port corresponding to a port program opened with the exit_status option.
Own Id: OTP-6411
A link removed via unlink/1 could under rare circumstances transfer exit signals for a short period of time after the call to unlink/1 had returned when the runtime system with SMP support was used.
Own Id: OTP-6425 Aux Id: OTP-6160

Improvements and New Features

In the runtime system with SMP support, ports are now being scheduled on the scheduler threads interleaved with processes instead of being run in a separate I/O thread.
Own Id: OTP-6262
More interfaces are added in erl_ddll, to support different usage scenarios.
Own Id: OTP-6307 Aux Id: OTP-6234
In the runtime system with SMP support, the global I/O lock has been replaced with a more fine grained port locking scheme. Port locking is either done on driver level, i.e., all ports executing the same driver share a lock, or on port level, i.e., each port has its own lock. Currently the inet driver, the efile driver, and the spawn driver use port level locking and all other statically linked in drivers use driver level locking. By default dynamically linked in drivers will use locking on driver level. For more information on how to enable port level locking see the erl_driver(3) and the driver_entry(3) man pages.
As of erts version 5.5.3 the driver interface has been extended. The extended interface introduce version management, the possibility to pass capability flags to the runtime system at driver initialization, and some new driver API functions. For example, the driver_system_info() function which can be used to determine if the driver is run in a runtime system with SMP support or not. The extended interface doesn't have to be used, but dynamically linked in driver have to be recompiled. For information see the erl_driver(3) and the driver_entry(3) man pages.
NOTE: Dynamically linked in drivers have to be recompiled.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-6330 Aux Id: OTP-6262
A test and debug feature which modifies the timing of the runtime system has been added. For more information, see documentation of the +T<Level> command line argument of erl.
Own Id: OTP-6382
The version of zlib (http://zlib.net) linked into run-time system has been updated to version 1.2.3.
Own Id: OTP-6394
The erlc program now passes on the -smp and -hybrid options to the Erlang emulator it starts. This is mainly useful for compiling native code, because native code must be compiled with same type of run-time system as in which it will be run.
If the -s option is given, erlc now prints a warning that it is deprecated and that it will be removed in R12B.
Own Id: OTP-6398
The schedulers option of erlang:system_flag/2 has been removed, i.e., the number of scheduler threads cannot be changed after emulator boot time any more.
A multi_scheduling option has been added to erlang:system_flag/2. This option can be used for blocking and unblocking multi-scheduling. For more information see the erlang documentation.
Own Id: OTP-6403
A port program that had been started with the exit_status option and closed one of the pipes used for communication with the emulator caused the emulator to continuously poll for termination of the port program. This only became a problem when the emulator didn't have other things to do and the port program closed a pipe much earlier than it terminated. When the emulator had other things to do, such as running Erlang processes, the emulator polled for termination in between scheduling of processes.
Now the emulator doesn't poll for termination of the port program at all; instead, it waits for the child signal from the terminated port program to arrive and then schedules the Erlang port for termination.
The termination of any port programs have also been optimized. Previously the termination of any port program did always cause a scan of a table of the size equal to maximum number of file descriptors. If the maximum number of file descriptors was large, this scan could be quite expensive. Now the search have been reduced to the set of ports started with the exit_status option.
Note, all of the above only applies to Erlang emulators on Unix platforms.
Own Id: OTP-6412 Aux Id: seq10194
* BEAM: added support for floating-point exceptions on FreeBSD (32-bit x86)
* SMP: made locking procedures work even when native lock operations aren't implemented
* SMP: improved timing accuracy in the timer thread (if enabled)
Own Id: OTP-6424

Erts 5.5.2.2

Fixed Bugs and Malfunctions

A bug in the kernel poll implementation could cause the emulator to omit polling for events on file descriptors. The bug was only present when using the kernel poll implementation based on epoll or kqueue. This bug was introduced in erts-5.5.2.
Own Id: OTP-6344 Aux Id: OTP-6222

Erts 5.5.2.1

Fixed Bugs and Malfunctions

The run_erl program now acquires its pseudo-ttys using openpty(3), so that it will work on newer Linux distributions that don't have the traditional pseudo-tty devices in the file system. On platforms that don't have openpty(3), run_erl will still search for pseudo-tty devices in the file system.
The run_erl program will now wait using waitpid(3) to prevent the program it spawned to become defunct. run_erl will also terminate after a delay of 5 seconds (to allow any pending output to be written to the log file) if the spawned program terminates even if some child of it still holds stdin and/or stdout open.
Own Id: OTP-6225 Aux Id: seq10500
A bug in ordered_set ETS datatyp caused ets:select (and match) to return faulty results when the table contained process id's from another node.
Own Id: OTP-6338

Erts 5.5.2

Fixed Bugs and Malfunctions

erlc: A typo in the help text for '-pa path' was corrected.
Own Id: OTP-6218
Failure in port command/control driver callbacks could crash the non-SMP emulator. This bug was introduced in the 5.5 version of erts.
Own Id: OTP-6224
Erroneous "Input driver gone away without deselecting!" error reports could sometimes occur when a driver instance terminated in the ready_output() callback of the driver. This bug was only present in emulators that used poll(). Note, that this bug was harmless, the only effect it had was the erroneous error report.
Own Id: OTP-6229 Aux Id: OTP-3993, Seq5266, Seq7247, OTP-4307
The emulator could cause a type assertion failure while writing an erl_crash.dump, causing the erl_crash.dump to be terminated and a core dump generated.
Own Id: OTP-6235 Aux Id: seq10444
The registered name of a process is now the last observable resource removed before links and monitors are triggered when a process terminates.
Previously ets tables were removed after the registered name. This could cause problems on the runtime system with SMP support for code that expected that ets tables owned by a specific process had been removed if the name of the process had been removed.
Own Id: OTP-6237
Failure to fork() a new (os) process could cause the emulator to deadlock. This bug affect all emulators with SMP support, and emulators with async thread support on SunOS.
Own Id: OTP-6241 Aux Id: OTP-3906
Fprof traces could become truncated for the SMP emulator. This bug has now been corrected.
Own Id: OTP-6246
The undocumented functions inet:getiflist/0,1 inet:ifget/2,3 and inet:getif/1 were completely broken on Windows. That has been fixed.
Own Id: OTP-6255
Behavior in case of disappeared nodes when using the dist_auto_connect once got changed in R11B-1. The timeouts regarding normal distributed operations is now reverted to the old (pre R11B-1).
Own Id: OTP-6258 Aux Id: OTP-6200, seq10449
The bsl and bsr operators could cause the emulator to crash if given invalid arguments. (Thanks to datacompboy and Per Gustafsson.)
Own Id: OTP-6259
driver_cancel_timer() could under certain circumstances fail to cancel the timer on the runtime system with SMP support.
Own Id: OTP-6261
A call to erlang:system_info(info) could deadlock the runtime system with SMP support.
Own Id: OTP-6268

Improvements and New Features

Exit signals are now truly asynchronous in the runtime system with SMP support. This simplifies locking in bifs a lot, and makes process termination cheaper.
Own Id: OTP-6160
When tracing on the runtime system with SMP support it can be difficult to know when a trace has been delivered to the tracer. A new built in function erlang:trace_delivered/1 has been introduced in order to make it easier to know when the trace has been delivered. See the erlang(3) man page for more information.
Own Id: OTP-6205 Aux Id: OTP-6269
Kernel poll support can now be combined with SMP support. Currently the following kernel poll versions exist: /dev/poll, epoll, and kqueue. Linux kpoll has been replaced with epoll. Some time in the future there will also be a kernel poll version using Solaris event ports.
The "check io" implementation for unix has been completely rewritten. The current kernel poll implementation reduce the amount of system calls needed compared to the old kernel poll implementation.
When epoll or kqueue is used either poll or select is used as fallback. Previously only poll could be used as fallback. Since select now can be used as fallback, kernel poll support is now also available on newer MacOSX. Note however, when select is used as fallback, the maximum number of file descriptors is limited to FD_SETSIZE.
Kernel poll support is now enabled by default if /dev/poll, epoll, or kqueue is found when building OTP, i.e. you do not have to pass the --enable-kernel-poll argument to configure. As before, kernel poll is disabled by default in the runtime system. In order to enable it, pass the +Ktrue command line argument to erl.
Note: configure will refuse to enable kernel poll support on FreeBSD since kqueue have problems with (at least) pipes on all version of FreeBSD that we have tested.
Own Id: OTP-6222 Aux Id: seq10380
The erl_ddll module and the code in the emulator have been completely rewritten; several bugs were fixed.
Own Id: OTP-6234
The SMP emulator now avoids locking for the following operations (thus making them as fast as in the UP emulator): atom_to_list/1, atom comparison, atom hashing, erlang:apply/3.
Own Id: OTP-6252
There are new BIFs erlang:spawn_monitor/1,3, and the new option monitor for spawn_opt/2,3,4,5.
The observer_backend module has been updated to handle the new BIFs.
Own Id: OTP-6281

Erts 5.5.1.1

Improvements and New Features

There is now an option read_packets for UDP sockets that sets the maximum number of UDP packets that will be read for each invocation of the socket driver.
Own Id: OTP-6249 Aux Id: seq10452

Erts 5.5.1

Fixed Bugs and Malfunctions

Complex pattern matching of strings would fail in the 64 bits emulator because of a bug in the loader. (Thanks to Igor Goryachev.)
Own Id: OTP-6142
-134217728 div 134217728 and -134217728 rem 134217728 would be calculated incorrectly. abs(-2147483648) could in unlucky circumstances cause a heap overflow, as could size(Binary) when size of the binary was larger than 128Mb.
Own Id: OTP-6154
erlang:display/1 displayed erroneous values for negative integers.
Big integers (both positive and negative) were previously displayed in hexadecimal form while small integers were displayed in decimal form. All integers are now displayed in decimal form.
NOTE: erlang:display/1 should only be used for debugging.
Own Id: OTP-6156
A call to erlang:trace/3 with erroneous flags caused the SMP emulator to deadlock instead of exiting the calling process with badarg.
Own Id: OTP-6175
A bug causing the emulator to hang when exiting a process that is exception traced has been fixed.
Own Id: OTP-6180
ets:rename/1 could deadlock, or crash the SMP emulator when the table wasn't a named table.
ets:next/2, and ets:prev/2 could return erroneous results on the SMP emulator.
Own Id: OTP-6198 Aux Id: seq10392, seq10415
A memory allocation bug could cause the SMP emulator to crash when a process had executed a receive after with a larger timeout than 10 minutes.
Own Id: OTP-6199
The runtime system with SMP support did not slowly adjust its view of time when the system time suddenly changed.
Timeouts could sometimes timeout too early on the runtime system with SMP support.
Own Id: OTP-6202

Improvements and New Features

The smp runtime system now automatically detects the number of logical processors on MacOSX (darwin) and OpenBSD.
The smp runtime system is now built by default on MacOSX (darwin) on x86.
Own Id: OTP-6119
The -smp command line argument now take the following options: enable, auto, or disable.
Especially the -smpauto argument is useful since it starts the Erlang runtime system with SMP support if it is available and more than one logical processor are detected; otherwise, it starts the Erlang runtime system without SMP support. For more information see the erl man page.
Own Id: OTP-6126
Increased the reduction cost for sending messages in the SMP emulator so it behaves more like the non-SMP emulator.
Own Id: OTP-6196
A port running a dynamically linked-in driver that exits due to the driver being unloaded now exits with exit reason driver_unloaded. Previously the port exited with exit reason -1.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-6204
Changed name of the erlang:system_info/1 argument scheduler to scheduler_id. This since the scheduler argument so easily could be mixed up with the schedulers argument (both returning integers).
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-6208
The changes below were made by Mikael Pettersson, HiPE.
HiPE runtime system:
Reduce overheads in the HiPE runtime system's BIF glue code.
Fix bug when exceptions are thrown from BEAM to HiPE.
Support SPARC on Linux.
Support x86 on FreeBSD.
Floating-point exceptions:
Reduce overheads in checking results of floating-point operations.
Minor bug fix in SSE2 floating-point exception handling.
Support SSE2 floating-point exceptions on 32-bit x86 machines.
Make FP exceptions work in the SMP runtime system on FreeBSD/x86.
Support floating-point exceptions on SPARCs running Linux.
Runtime system:
Minor scheduler optimisation in the non-SMP runtime system.
Substantial reduction of I/O thread overheads in the SMP runtime system if the separate timer thread is used. (In R11B-1, the separate timer thread is not used.)
Own Id: OTP-6211

ERTS 5.5

Fixed Bugs and Malfunctions

Previously unlink/1 and erlang:demonitor/2 behaved completely asynchronous. This had one undesirable effect, though. You could never know when you were guaranteed not to be affected by a link that you had unlinked or a monitor that you had demonitored.
The new behavior of unlink/1 and erlang:demonitor/2 can be viewed as two operations performed atomically. Asynchronously send an unlink signal or a demonitor signal, and ignore any future results of the link or monitor.
NOTE: This change can cause some obscure code to fail which previously did not. For example, the following code might hang:
```
            Mon = erlang:monitor(process, Pid),
            %% ...
            exit(Pid, bang),
            erlang:demonitor(Mon),
            receive
                {'DOWN', Mon , process, Pid, _} -> ok
            %% We were previously guaranteed to get a down message
            %% (since we exited the process ourself), so we could
            %% in this case leave out:
            %% after 0 -> ok
            end,
```
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-5772
Two bugs fixed: If the environment variable ERL_FLAGS was set, its contents would be appended to the end of the command line even if the command line had an -extra options. Changed to place the options from ERL_FLAGS just before -extra. Also, the -smp and -hybrid flags no longer have any effect if placed after -extra.
Own Id: OTP-6054

Improvements and New Features

The documentation for writing drivers in the ERTS User's Guide has been expanded and updated.
Own Id: OTP-5192
The andalso and orelse operators are now allowed to be used in guards. That also applies to match specifications.
Own Id: OTP-5894 Aux Id: OTP-5149
There is a new trace match spec function {exception_trace} and a corresponding trace message exception_from that can be used to trace on any exit from a function, both normal function return and exception return. See the documentation for details.
The return_to trace message is now also generated when the execution returns to a function due to catching an exception.
Own Id: OTP-5956
Erlang runtime system with SMP (symmetric multi processing) support.
The runtime system with SMP support is in this release focused on stability and there are a number of steps with optimizations to follow before it will take full advantage of multi processor systems. The released system is however truly multi threaded and you will notice increased performance for many applications already. We recommend that you evaluate your application on the SMP version of the runtime system and wait for some more optimizations before you use it in a real product. You will then discover if there are any problems in your application that needs to be fixed in order for it to work properly in a multi threaded environment. More optimized versions of the runtime system with SMP support will be included in the R11B maintenance releases.
The SMP enabled runtime system will be started if the -smp command line argument is passed to the erl command. In order to make use of more than one processor core, multiple scheduler threads are used. By default, the number of scheduler threads will equal the number of processor cores. The number of scheduler threads can be set with the +S command line argument. For more information see the erl man page.
A runtime system with SMP support is by default built on the following platforms if posix threads, and a gcc compiler of at least version 2.95 is found:
- Linux with at least kernel version 2.6 and the Native POSIX Thread Library on x86, x86_64, and 32-bits PowerPC.
- Solaris of at least version 8 on 32-bits SPARC-V9.
- MacOSX of at least version 10.4 (Darwin 8.0) on 32-bits PowerPC.
The runtime system with SMP support is known not to build on:
- Windows.
- Linux with kernel versions less than 2.4, or without the Native POSIX Thread Library.
- Other hardware platforms than x86, x86_64, 32-bits SPARC-V9 and 32-bits PowerPC.
Windows will be supported in a future release.
The runtime system with SMP support might build on other operating systems in combination with supported hardware. In order to force a build of a runtime system with SMP support, pass the --enable-smp-support command line argument to configure. Note, however, that it is not enough that it builds. The underlying thread library and operating system has to provide SMP support as well. If the thread library does not distribute scheduler threads over multiple processor cores then the runtime system will only seemingly provide SMP support. If the runtime system is not built by default on a specific platform, we have not tested it on that platform.
NOTE: The design of SMP support for drivers is ongoing. There will probably be incompatible driver changes (only affecting drivers run on the runtime system with SMP support) released as patches for R11B.
Potential incompatibility: Previously, specific driver call-backs were always called from the same thread. This is not true in the runtime system with SMP support. Calls to call-backs will be made from different threads, e.g., two consecutive calls to exactly the same call-back can be made from two different threads. This will in most cases not be a problem. All calls to call-backs are synchronized, i.e., only one call-back will be called at a time.
In the future the default behavior will probably be the following: Calls to call-backs will, as now, be made from different threads. Calls to call-backs in the same driver instance will be synchronized. It will probably be possible to configure so that all calls to call-backs in all driver instances of a specific driver type will be synchronized. It may be possible to configure so that all calls to call-backs of a driver instance or a of a specific driver type will be made from the same thread.
Parallelism in the Erlang code executed is a necessity for the Erlang runtime system to be able to take advantage of multi-core or multi-processor hardware. There need to be at least as many Erlang processes runnable as processor cores for the Erlang runtime system to be able to take advantage of all processor cores.
An Erlang runtime system with SMP support with only one Erlang process runnable all the time will almost always be slower than the same Erlang runtime system without SMP support. This is due to thread synchronization overhead.
Known major bottleneck in the Erlang runtime system:
- Currently the I/O system uses one "big lock", i.e. only one thread can do I/O at a time (with the exception of async threads and threads created by users own linked-in drivers). This is high on the list of things to optimize. Note, code that does not do I/O can be executed at the same time as one thread does I/O.
Some pitfalls which might cause Erlang programs that work on the non-SMP runtime system to fail on the SMP runtime system:
- A newly spawned process will often begin executing immediately. Code that expects that the parent process will be able to execute for a while before the child process begins executing is likely to fail.
- High priority processes could previously provide mutual exclusion (bad programming style) by preventing normal and low priority processes from being run. High priority processes cannot be used this way to provide mutual exclusion.
- erlang:yield() could be used to provide some kind of temporary mutual exclusion (also bad programming style). erlang:yield() cannot be used to provide any kind of mutual exclusion.
- Obscure pitfall, only if a process being traced also sends normal messages to the tracer:
  The order between trace messages and normal messages is undefined. I.e. the order between normal messages sent from a tracee to a tracer and the trace messages generated from the same tracee to the same tracer is undefined. The internal order of normal messages and the internal order of trace messages will, of course, be preserved as before.
The kernel poll feature is currently not supported by the runtime system with SMP support. It will probably be supported in a future release.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-6006 Aux Id: OTP-6095
Linked-in driver modifications.
- Linked-in drivers must be recompiled.
- The refc field in the ErlDrvBinary type has been removed. The reference count can be accessed via API functions. For more information see the erl_driver(3) man page.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-6095 Aux Id: OTP-6006

ERTS 5.4.13

Fixed Bugs and Malfunctions

Large files (more than 2 GBytes) are now handled on Solaris 8.
Own Id: OTP-5849 Aux Id: seq10157
A failing bit syntax construction could fail with the PREVIOUS exception reason that had occurred in the process (instead of with badarg).
Own Id: OTP-5911
When building OTP, the Kernel application was built in both the primary and secondary bootstrap steps, which would cause problems if OTP including its bootstrap is checked into a version control system (such as CVS). (Thanks to Sebastian Strollo.)
Own Id: OTP-5921
binary_to_term(<<131,109,255,255,255,255) and similar expressions used to crash the emulator instead of causing a badarg exception. (Thanks to Matthias Lang.)
Own Id: OTP-5933
erlang:hibernate/3 could sometimes crash the emulator when no heap was needed.
Own Id: OTP-5940
Execution of match specs could under rare circumstances cause the emulator to dump core.
Execution of match specs could cause memory leaks in the hybrid emulator.
Own Id: OTP-5955
A bug in erlang:trace_info/2 when getting info for a function in a deleted module resulting in an emulator crash, has been corrected.
Own Id: OTP-5957
Different (and old) config.guess files in the ERTS and Erl_Interface applications would cause build problems on the new Intel-based iMacs. (Thanks to Sebastion Strollo.)
Own Id: OTP-5967
pthread header and library mismatch on Linux systems (at least some SuSE and Debian) with both NPTL and Linuxthreads libraries installed.
Own Id: OTP-5981

Improvements and New Features

The driver_set_timer did not change the previous timeout if called a second time. Now it works as specified, changing the timeout.
Own Id: OTP-5942
The undocumented {packet,http} option (for the gen_tcp module) did not work correctly when there were multiple continuation lines. (Thanks to Per Hedeland.)
Own Id: OTP-5945
The setuid_socket_wrap program was corrected to work for C compilers that treat the char type as unsigned. (Thanks to Magnus Henoch.)
Own Id: OTP-5946

ERTS 5.4.12

Fixed Bugs and Malfunctions

Fixed a minor build problem on Windows.
Own Id: OTP-5819 Aux Id: OTP-5382 OTP-5540 OTP-5577
The delay_send option for gen_tcp was broken on Windows.
Own Id: OTP-5822
If there were user-defined variables in the boot script, and their values were not provided using the -boot_var option, the emulator would refuse to start with a confusing error message. Corrected to show a clear, understandable message.
The prim_file module was modified to not depend on the lists module, to make it possible to start the emulator using a user-defined loader. (Thanks to Martin Bjorklund.)
Own Id: OTP-5828 Aux Id: seq10151

Improvements and New Features

The HiPE compiler identifies more leaf functions, giving slightly faster code.
Corrected problems in HiPE's coalescing register allocating that would cause it to fail when compiling very large functions (e.g. some of parse modules in the Megaco application).
Own Id: OTP-5853

ERTS 5.4.11

Fixed Bugs and Malfunctions

Timers could sometimes timeout too early. This bug has now been fixed.
Automatic cancellation of timers created by erlang:send_after(Time,pid(),Msg) and erlang:start_timer(Time,pid(),Msg) has been introduced. Timers created with the receiver specified by a pid, will automatically be cancelled when the receiver exits. For more information see the erlang man page.
In order to be able to maintain a larger amount of timers without increasing the maintenance cost, the internal timer wheel and bif timer table have been enlarged.
Also a number of minor bif timer optimizations have been implemented.
Own Id: OTP-5795 Aux Id: OTP-5090, seq8913, seq10139, OTP-5782
erlang:monitor(process,Pid) hanged if Pid referred to a process on a non-existing node with the same nodename as the nodename of node on which the call was made. This bug has now been fixed.
Own Id: OTP-5827

Improvements and New Features

By setting Unix environment variables, the priority for the emulator can be lowered when it is writing crash dumps and the time allowed for finishing writing a crash dump can be set to a certain number of seconds. See the documentation for erl in the ERTS application. (Also, a few other previously undocumented environment variables are now documented.)
Own Id: OTP-5818
Documentation improvements:
- documentation for erlang:link/1 corrected
- command line flag -code_path_cache added
- erl command line flags clarifications
- net_kernel clarifications
Own Id: OTP-5847

ERTS 5.4.10

Fixed Bugs and Malfunctions

-D_GNU_SOURCE is now always passed on the compile command line on linux. This in order to ensure that all included system headers see _GNU_SOURCE defined.
_GNU_SOURCE is now also defined on linux in configure when looking for features.
Some minor (harmless) configure bugs were also fixed.
Own Id: OTP-5749
Some compiler warnings and Dialyzer warnings were eliminated in the Tools application.
When tracing to a port (which fprof does), there could be fake schedule out/schedule in messages sent for a process that had exited.
Own Id: OTP-5757

Improvements and New Features

The BIFs iolist_size/1 and iolist_to_binary/1 has been added.
The BIF list_to_existing_atom/1 has been added.
Minor bug fix: The exception reason could be changed to error inside nested try/catch constructs if the erlang:raise/3 BIF was called with an empty stacktrace. (Calling erlang:raise/3 with an empty stacktrace is NOT recommended.)
Minor bugfix: On Windows, file:open/2 will now return the documented error reason {error,eisdir} if the filename refers to a directory (it used to return {error,eacces}).
The message in the documentation for erlang:system_monitor/2, description of busy_dist_port, was corrected.
Own Id: OTP-5709 Aux Id: seq10100
The previously undocumented and UNSUPPORTED zlib module has been updated in an incompatible way and many bugs have been corrected. It is now also documented.
* POTENTIAL INCOMPATIBILITY *
Own Id: OTP-5715
New socket options priority and tos for platforms that support them (currently only Linux).
Own Id: OTP-5756
Only the emulator is now linked with termcap library in order to decrease library dependencies for other otp programs.
Own Id: OTP-5758

ERTS 5.4.9.2

Fixed Bugs and Malfunctions

The native resolver has gotten an control API for extended debugging and soft restart. It is: inet_gethost_native:control(Control)
Control = {debug_level,Level} | soft_restart
Level = integer() in the range 0-4.
Own Id: OTP-5751 Aux Id: EABln25013

ERTS 5.4.9.1

Improvements and New Features

On VxWorks, epmd did not handle file descriptors with higher numbers than 63. Also, if epmd should get a file descriptor with a number >= FD_SETSIZE, it will close a the file descriptor and write a message to the log (instead of mysteriously fail); the Erlang node that tried to register will fail with a duplicate_name error (unfortunately, epmd has no way to indicate to the Erlang node why the register attempt failed).
Own Id: OTP-5716 Aux Id: seq10070

ERTS 5.4.9

Fixed Bugs and Malfunctions

Timezone data is now initialized better. (was a problem at least on NetBSD 2.0.2) Thanks to Rich Neswold.
Own Id: OTP-5621
The hybrid-heap emulator ('erl -hybrid') is much more stable. We have corrected all known bugs that caused it to dump core while running our test suites.
Own Id: OTP-5634
Fixed rare memory leaks in erlang:demonitor/1 when distributed monitors were removed.
Own Id: OTP-5692
Processes were sometimes unnecessarily garbage collected when terminating. These unnecessary garbage collections have now been eliminated.
Own Id: OTP-5693

Improvements and New Features

The c:i/0 function will now run in a paged mode if there are more than 100 processes in the system. (Thanks to Ulf Wiger.)
erlang:system_info(process_count) has been optimized and does now return exactly the same value as length(processes()). Previously erlang:system_info(process_count) did not include exiting processes which are included in length(processes()).
The +P flag for erl, which sets the maximum number of processes allowed to exist at the same, no longer accepts values higher than 134217727. (You will still probably run out of memory before you'll be able to reach that limit.)
Own Id: OTP-5645 Aux Id: seq9984
The term-building driver functions driver_output_term() and driver_send_term() have been updated:
The ERL_DRV_FLOAT type has been added.
For the ERL_DRV_BINARY type, the length and offset are now validated against the length of the driver binary.
The ERL_DRV_PID type is now implemented (it was documented, but not implemented).
Own Id: OTP-5674

ERTS 5.4.8

Fixed Bugs and Malfunctions

ets:delete/1 now allows other Erlang process to run when a large table is being deleted.
Own Id: OTP-5572
A bug regarding tcp sockets which results in hanging gen_tcp:send/2 has been corrected. To encounter this bug you needed one process that read from a socket, one that wrote more date than the reader read out so the sender got suspended, and then the reader closed the socket. (Reported and diagnosed by Alexey Shchepin.)
Corrected a bug in the (undocumented and unsupported) option {packet,http} for gen_tcp. (Thanks to Claes Wikstrom and Luke Gorrie.)
Updated the documentation regarding the second argument to gen_tcp:recv/2, the Length to receive.
Own Id: OTP-5582 Aux Id: seq9839
Erlang/OTP will now build on Mac OS X 10.4 "Tiger" (the problem was that 10.4 has a partially implemented poll() function that can't handle devices). Also, on Mac OS X 10.3 "Panther", Erlang/OTP will now use select() instead of poll() (because poll() on Mac OS X 10.3 is implemented using select()).
Own Id: OTP-5595
A bug in the file driver when opening a file in compressed mode, and the returned allocated pointer from the compressing library was in very high memory (>= 2GB), causing e.g. file:read/2 to return {error,ebadf}, has been corrected.
Own Id: OTP-5618

Improvements and New Features

The new fun M:F/A construct creates a fun that refers to the latest version of M:F/A. This syntax is meant to replace tuple funs {M,F} which have many problems.
The new type test is_function(Fun,A) (which may be used in guards) test whether Fun is a fun that can be applied with A arguments. (Currently, Fun can also be a tuple fun.)
Own Id: OTP-5584
In the HiPE application, there's a new experimental register allocator (optimistic coalescing), and the linear scan register allocator is now also available on ppc. Plus lots of cleanups.
Minor hybrid heap corrections.
The maximum size of a heap used to be artificially limited so that the size of a heap would fit in 28 bits; that limitation could cause the emulator to terminate in a garbage collection even if there still was available memory. Now the largest heap size for a 32 bit CPU is 1,699,221,830 bytes. (Thanks to Jesper Wilhelmsson.)
Also removed the undocumented +H emulator option.
Own Id: OTP-5596

ERTS 5.4.7

Fixed Bugs and Malfunctions

to_erl could close unexpectedly on Linux systems. Also, output from the emulator could be lost. Corrected.
Own Id: OTP-5561

Improvements and New Features

The cpu_timestamp option for erlang:trace/3 is now also supported on Linux.
Own Id: OTP-5532 Aux Id: seq9813
The last known werl window size/position is now saved correctly when werl is stopped with the window minimized. A problem with the placement not being saved if the emulator is halted or stopped from the JCL menu has also been fixed.
Own Id: OTP-5544 Aux Id: OTP-5522

ERTS 5.4.6

Fixed Bugs and Malfunctions

Some math libraries do not always throw floating-point exceptions on errors. In order to be able to use these libraries, floating-point errors are now more thoroughly checked.
Misc floating-point fixes for Linux and MacOSX.
Own Id: OTP-5467
An internal buffer was sometimes not cleared which caused garbage to appear in error messages sent to the error logger.
errno was sometimes clobbered which caused erroneous error reports about poll() errors.
Only emulators on unix platforms were affected by these bugs.
Own Id: OTP-5492
The ethread library now works on OpenBSD.
Own Id: OTP-5515
Corrected a bug in the (undocumented and unsupported) option {packet,http} for gen_tcp. (Thanks to Claes Wikstrom and Luke Gorrie.)
Own Id: OTP-5519

Improvements and New Features

binary_to_term/1 could cause the emulator to crash when given invalid pids or funs.
Own Id: OTP-5484 Aux Id: seq9801
Some more stability problems were fixed in the hybrid-heap emulator.
Own Id: OTP-5489
After werl was closed with the window minimized, it was not possible to restart werl with an open window. A temporary solution has so far been implemented that restores the initial window settings every time werl is started.
Own Id: OTP-5522

ERTS 5.4.5

Fixed Bugs and Malfunctions

If a process had node links (created by monitor_node/2), executing process_info(Pid,memory) for that process would crash the emulator.
Own Id: OTP-5420
Minor corrections to the help text printed by erlc -help. The documentation for erlc was also slightly updated.
Own Id: OTP-5428
32-bit words were used for offsets in the garbage collector. This caused the emulator to crash on 64-bit machines when heaps were moved more than 4 GB during garbage collection.
Own Id: OTP-5430
is_boolean(42.5) failed to load if optimization was explicitly turned off.
Own Id: OTP-5448
If there was a call to Module:foo/X from any loaded module, the returned by M:module_info(exports) would always include {foo,X} (even though Module:foo/X if was not defined).
Own Id: OTP-5450 Aux Id: seq9722

Improvements and New Features

The c option for the +B flag has been introduced which makes it possible to use Ctrl-C (Ctrl-Break on Windows) to interrupt the shell process rather than to invoke the emulator break handler. All new +B options are also supported on Windows (werl) as of now. Furthermore, Ctrl-C on Windows has now been reserved for copying text (what Ctrl-Ins was used for previously). Ctrl-Break should be used for break handling. Lastly, the documentation of the system flags has been updated.
Own Id: OTP-5388

ERTS 5.4.4

Fixed Bugs and Malfunctions

The function erlang:float/1 can now be used in match specifications and is recognized by dbg:fun2ms/1 and ets:fun2ms/1. This addition is part of the work to "harmonize" match specification guards with Erlang guards.
Own Id: OTP-5297 Aux Id: OTP-4927
The register/2 BIF would return true even if the second argument was not a pid for living process. Corrected to cause an exception.
Own Id: OTP-5324 Aux Id: seq9698
In the 'bag' type of ets tables, elements having the same key were supposed to be order in insertion order. The would be wrong if a rehash occurred.
Own Id: OTP-5340 Aux Id: seq9704
Linked in drivers in the Crypto and Asn1 applications are now compiled with the -D_THREAD_SAFE and -D_REENTRANT switches on unix when the emulator has thread support enabled.
Linked in drivers on MacOSX are not compiled with the undocumented -lbundle1.o switch anymore. Thanks to Sean Hinde who sent us a patch.
Linked in driver in Crypto, and port programs in SSL, now compiles on OSF1.
Minor makefile improvements in Runtime_Tools.
Own Id: OTP-5346
Fixed a bug in the hybrid heap in distributed send operations.
Own Id: OTP-5361
A BIF erlang:raise/3 has been added. See the manual for details. It is intended for internal system programming only, advanced error handling.
Own Id: OTP-5376 Aux Id: OTP-5257
Mikael Pettersson (HiPE) corrected a few bugs in the emulator that caused problems when compiled with the experimental gcc-4.0.0.
Own Id: OTP-5386

Improvements and New Features

Minor update of the internal documentation of the epmd protocol.
The listen port of epmd has now been registered at IANA: http://www.iana.org/assignments/port-numbers.
Own Id: OTP-5234
run_erl.c now works on Mac OS X and FreeBSD.
Own Id: OTP-5384
A few bugs were corrected in the HiPE application.
Own Id: OTP-5385

ERTS 5.4.3

Fixed Bugs and Malfunctions

Font and color preferences for werl.exe now can be saved even after the first time you run werl.exe. The window position and size is also saved. Patch from James Hague who did all the hard work.
Own Id: OTP-5250
OTP archive libraries, e.g. the erl_interface library, on MacOSX could not be used without first rerunning ranlib on them. This bug has now been fixed.
Own Id: OTP-5274
Bugs in erlang:hash/2 and erlang:phash/2 on 64-bit platforms have been fixed.
Own Id: OTP-5292

Improvements and New Features

Corrected a crash in the 64-bits emulator.
Corrected a problem in the hybrid heap emulator.
In the chapter about the abstract format in the ERTS User's Guide, updated the last section about how the abstract format is stored in BEAM files.
Own Id: OTP-5262
The maximum number of concurrent threads in the internal ethread thread package has been limited to 2048.
Own Id: OTP-5280

ERTS 5.4.2.1

Improvements and New Features

If Erlang/OTP was installed in a short directory name, such as C:\Program\erl5.4.2, the emulator would not start.
Own Id: OTP-5254

ERTS 5.4.2

Fixed Bugs and Malfunctions

If one used select/3 and select/1 on a non-fixed ETS table and deleted objects simultaneously, the emulator could crash. Note that the result of such simultaneous operations on tables that are not in a fixed state is still undefined, but the emulator crash is, needless to say, fixed.
Own Id: OTP-5209 Aux Id: seq9198
Arithmetic with big numbers could crash the emulator.
The HiPE native code compiler and run-time code in the emulator has been updated. (Note: Native code is still not supported.)
Eliminated a few bugs that could crash the hybrid emulator (which is not supported).
Own Id: OTP-5233 Aux Id: seq9587

ERTS 5.4.1

Fixed Bugs and Malfunctions

The ethread library was unnecessarily rebuilt multiple times during the build process, also a debug version of the library was build during the install phase. These unnecessary builds have now been removed. Note, the content of the installed Erlang/OTP system is not effected at all by this change.
Own Id: OTP-5203
The emulator could fail to clear the memory segment cache. This could potentially cause memory allocation to unnecessarily fail when memory usage was close to its maximum. This bug has now been fixed.
Own Id: OTP-5211
std_alloc (std short for standard) was sometimes called def_alloc (def short for default). std_alloc is now everywhere referred to as std_alloc.
Own Id: OTP-5216
A documentation bug has been corrected in the erts_alloc(3) documentation. It was stated that some of the memory allocators present were by default disabled. This is true for Erlang/OTP R9C, but is not true for Erlang/OTP R10B. In R10B all memory allocators present are enabled by default.
Own Id: OTP-5217

Improvements and New Features

The emulator now close all open files and sockets immediately after receiving an USR1 signal. This causes the emulator to unregister at epmd as early as possible.
Own Id: OTP-5221 Aux Id: OTP-4985, seq9514
Try/catch support in the emulator slightly updated.
Own Id: OTP-5229

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