1 Kernel Release Notes

This document describes the changes made to the Kernel application.

1.1 Kernel 2.13.4

Fixed Bugs and Malfunctions

A link in pg2(3) has been fixed. (Thanks to Christophe Romain.)

Own Id: OTP-8198
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
A bug in pg2 when members who died did not leave process groups has been fixed. (Thanks to Matthew Dempsky.)

Own Id: OTP-8259

Improvements and New Features

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
The top directory in archive files does not need to have a -vsn suffix anymore. For example if the archive file has the name like mnesia-4.4.7.ez the top directory in the archive can either be named mnesia or mnesia-4.4.7. If the archive file has a name like mnesia.ez the top directory in the archive must be named mnesia as earlier.

Own Id: OTP-8266
The -on_load() directive can be used to run a function when a module is loaded. It is documented in the section about code loading in the Reference Manual.

Own Id: OTP-8295

1.2 Kernel 2.13.3

Improvements and New Features

The DNS resolver client inet_res has been rewritten, documented and released. See inet_res(3) and Erts User's Guide: Inet configuration.

It can formally not be incompatible with respect to earlier versions since there was no earlier official version. However it was used before and some details have changed.

Configuration now initializes from /etc/resolv.conf and /etc/hosts on all unix platforms regardless of which distribution mode the node is started in. The directory (/etc) these files are supposed to reside in can be changed via an environment variable. These configuration file locations can also be changed in the inet configuration. The files are monitored for change and re-read, which makes a few resolver configuration variables out of application control. The /etc/hosts entries have now their own cache table that is shadowed (with lookup method 'file' is used) by the application configured host entries. This problem (that inet_res configuration only worked for distribution mode long names) was among other reported by Matthew O'Gorman many moons ago.

The lookup methods are still 'native' only per default. Resolver configuration is done on all Unix platforms just to get a usable configuration for direct calls to inet_res.

The functions inet_res:nslookup/3..5 and inet_res:nnslookup/4..4 are no longer recommended to use, instead use inet_res:lookup/3..5 and inet_res:resolve/3..5 which provide clearer argument types and the possibility to override options in the call.

Users of previous unsupported versions of inet_res have included internal header files to get to the internal record definitions in order to examine DNS replies. This is still unsupported and there are access functions in inet_dns to use instead. These are documented in inet_res(3).

Bug fix: a compression reference loop would make DNS message decoding loop forever. Problem reported by Florian Weimer.

Bug fix and patch suggestion by Sergei Golovan: configuring IPv6 nameservers did not work. His patch (as he warned) created many UDP sockets; one per nameserver. This has been fixed in the released version.

Improvement: inet_res is now EDNS0 capable. The current implementation is simple and does not probe and cache EDNS info for nameservers, which a fully capable implementation probably should do. EDNS has to be enabled via resolver configuration, and if a nameserver replies that it does not support EDNS, inet_res falls back to a regular DNS query.

Improvement: now inet_res automatically falls back to TCP if it gets a truncated answer from a nameserver.

Warning: some of the ancient and exotic record types handled by inet_res and inet_dns are not supported by current versions of BIND, so they could not be tested after the rewrite, with reasonable effort, e.g MD, MF, NULL, and SPF. The risk for bugs in these particular records is still low since their code is mostly shared with other tested record types.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-7955 Aux Id: OTP-7107 OTP-6852
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 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

1.3 Kernel 2.13.2

Fixed Bugs and Malfunctions

A bug when doing io:get_line (among other calls) from a file opened with encoding other than latin1, causing false unicode errors to occur, is now corrected.

Own Id: OTP-7974

Improvements and New Features

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

1.4 Kernel 2.13.1

Fixed Bugs and Malfunctions

Many concurrent calls to os:cmd/1 will only block one scheduler thread at a time, making an smp emulator more responsive if the OS is slow forking processes.

Own Id: OTP-7890 Aux Id: seq11219
Fixed hanging early RPC that did IO operation during node start.

Own Id: OTP-7903 Aux Id: seq11224
The error behavior of gen_tcp and gen_udp has been corrected. gen_tcp:connect/3,4 and gen_udp:send/4 now returns {error,eafnosupport} for conflicting destination address versus socket address family. Other corner cases for IP address string host names combined with not using the native (OS) resolver (which is not default) has also been changed to return {error,nxdomain} instead of {error,einval}. Those changes just may surprise old existing code. gen_tcp:listen/2 and gen_udp:open/2 now fails for conflicting local address versus socket address family instead of trying to use an erroneous address. Problem reported by Per Hedeland.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-7929

Improvements and New Features

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
The unsupported DNS resolver client inet_res has now been improved to handle NAPTR queries.

Own Id: OTP-7925 Aux Id: seq11231

1.5 Kernel 2.13

Fixed Bugs and Malfunctions

The old Erlang DNS resolver inet_res has been corrected to handle TXT records with more than one character string. Patch courtesy of Geoff Cant.

Own Id: OTP-7588
When chunk reading a disk log opened in read_only mode, bad terms could crash the disk log process.

Own Id: OTP-7641 Aux Id: seq11090
gen_tcp:send() did sometimes (only observed on Solaris) return {error,enotconn} instead of the expected {error,closed} as the peer socket had been explicitly closed.

Own Id: OTP-7647
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

Improvements and New Features

Erlang programs can now access STDERR on platforms where such a file descriptor is available by using the io_server 'standard_error', i.e. io:format(standard_error,"~s~n",[ErrorMessage]),

Own Id: OTP-6688
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
As of this version, the global name server no longer supports nodes running Erlang/OTP R10B.

Own Id: OTP-7661
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 deprecated functions erlang:fault/1, erlang:fault/2, and file:rawopen/2 have been removed.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-7812
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
The copyright notices have been updated.

Own Id: OTP-7851

1.6 Kernel 2.12.5.1

Fixed Bugs and Malfunctions

When chunk reading a disk log opened in read_only mode, bad terms could crash the disk log process.

Own Id: OTP-7641 Aux Id: seq11090
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

1.7 Kernel 2.12.5

Fixed Bugs and Malfunctions

The documentation of rpc:pmap/3 has been corrected. (Thanks to Kirill Zaborski.)

Own Id: OTP-7537
The listen socket used for the distributed Erlang protocol now uses the socket option 'reuseaddr', which is useful when you force the listen port number using kernel options 'inet_dist_listen_min' and 'inet_dist_listen_max' and restarts a node with open connections.

Own Id: OTP-7563
Fixed memory leak of unclosed TCP-ports. A gen_tcp:send() followed by a failing gen_tcp:recv() could in some cases cause the port to linger after being closed.

Own Id: OTP-7615

Improvements and New Features

Processes spawned using proc_lib (including gen_server and other library modules that use proc_lib) no longer keep the entire argument list for the initial call, but only the arity.

Also, if proc_lib:spawn/1 is used to spawn a fun, the actual fun is not kept, but only module, function name, and arity of the function that implements the fun.

The reason for the change is that keeping the initial fun (or a fun in an argument list), would prevent upgrading the code for the module. A secondary reason is that keeping the fun and function arguments could waste a significant amount of memory.

The drawback with the change is that the crash reports will provide less precise information about the initial call (only Module:Function/Arity instead of Module:Function(Arguments)). The function proc_lib:initial_call/1 still returns a list, but each argument has been replaced with a dummy atom.

Own Id: OTP-7531 Aux Id: seq11036
io:get_line/1 when reading from standard input is now substantially faster. There are also some minor performance improvements in io:get_line/1 when reading from any file opened in binary mode. (Thanks to Fredrik Svahn.)

Own Id: OTP-7542
There is now experimental support for loading of code from archive files. See the documentation of code, init, erl_prim_loader and 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
code:is_sticky/1 is now documented. (Thanks to Vlad Dumitrescu.)

Own Id: OTP-7561
In the job control mode, the "s" and "r" commands now take an optional argument to specify which shell to start. (Thanks to Robert Virding.)

Own Id: OTP-7617
net_adm:world/0,1 could crash if called in an emulator that has not been started with either the -sname or -name option; now it will return an empty list. (Thanks to Edwin Fine.)

Own Id: OTP-7618

1.8 Kernel 2.12.4

Fixed Bugs and Malfunctions

Large files are now handled on Windows, where the filesystem supports it.

Own Id: OTP-7410

Improvements and New Features

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
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

1.9 Kernel 2.12.3

Fixed Bugs and Malfunctions

SCTP_ADDR_CONFIRMED events are now handled by gen_sctp.

Own Id: OTP-7276
When leaving a process group with pg2:leave/2 the process was falsely assumed to be a member of the group. This bug has been fixed.

Own Id: OTP-7277
In the Erlang shell, using up and down arrow keys, the wrong previous command could sometimes be retrieved.

Own Id: OTP-7278
The documentation for erlang:trace/3 has been corrected.

Own Id: OTP-7279 Aux Id: seq10927
In the SMP emulator, there was small risk that code:purge(Mod) would kill a process that was running code in Mod and unload the module Mod before the process had terminated. code:purge(Mod) now waits for confirmation (using erlang:monitor/2) that the process has been killed before proceeding.

Own Id: OTP-7282
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

Improvements and New Features

Additional library directories can now be specified in the environment variable ERL_LIBS. See the manual page for the code module. (Thanks to Serge Aleynikov.)

Own Id: OTP-6940
crypto and zlib drivers improved to allow concurrent smp access.

Own Id: OTP-7262
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
The hide option for open_port/2 is now documented. (Thanks to Richard Carlsson.)

Own Id: OTP-7358

1.10 Kernel 2.12.2.1

Improvements and New Features

os:cmd/1 on unix platforms now use /bin/sh as shell instead of looking for sh in the PATH environment.

Own Id: OTP-7283

1.11 Kernel 2.12.2

Fixed Bugs and Malfunctions

A bug caused by a race condition involving disk_log and pg2 has been fixed.

Own Id: OTP-7209 Aux Id: seq10890
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

Improvements and New Features

erlang:system_info/1 now accepts the logical_processors, and debug_compiled arguments. For more info see the, erlang(3) 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
Updated the documentation for erlang:function_exported/3 and io:format/2 functions to no longer state that those functions are kept mainly for backwards compatibility.

Own Id: OTP-7186
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
tuple_size/1 and byte_size/1 have been substituted for size/1 in the documentation.

Own Id: OTP-7244

1.12 Kernel 2.12.1.2

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(3) documentation.

Own Id: OTP-7167

1.13 Kernel 2.12.1.1

Fixed Bugs and Malfunctions

Fixed a problem in group that could cause the ssh server to lose answers or hang.

Own Id: OTP-7185 Aux Id: seq10871

1.14 Kernel 2.12.1

Fixed Bugs and Malfunctions

file:read/2 and file:consult_stream/1,3 did not use an empty prompt on I/O devices. This bug has now been corrected.

Own Id: OTP-7013
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

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
tuple_size/1 and byte_size/1 have been substituted for size/1.

Own Id: OTP-7009

1.15 Kernel 2.12

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
A bug in gen_udp:fdopen reported by David Baird and also found by Dialyzer has been fixed.

Own Id: OTP-6836 Aux Id: OTP-6594
Calling error_logger:tty(true) multiple times does not give multiple error log printouts.

Own Id: OTP-6884 Aux Id: seq10767
The global name server now ignores nodeup messages when the command line flag -connect_all false has been used. (Thanks to Trevor Woollacott.)

Own Id: OTP-6931
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

Minor documentation corrections for file:pread/2 and file:pread/3.

Own Id: OTP-6853
The deprecated functions file:file_info/1, init:get_flag/1, init:get_flags/0, and init:get_args/0 have been removed.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-6886
Contract directives for modules in Kernel and STDLIB.

Own Id: OTP-6895
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
The undocumented and unsupported functions inet:ip_to_bytes/1, inet:ip4_to_bytes/1, inet:ip6_to_bytes/1, and inet:bytes_to_ip6/16 have been removed.

Own Id: OTP-6938
Added new checksum combine functions to zlib. And fixed a bug in zlib:deflate. Thanks Matthew Dempsky.

Own Id: OTP-6970
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
All functions in the code module now fail with an exception if they are called with obviously bad arguments, such as a tuple when an atom was expected. Some functions now also fail for undocumented argument types (for instance, ensure_loaded/1 now only accepts an atom as documented; it used to accept a string too).

Dialyzer will generally emit warnings for any calls that use undocumented argument types. Even if the call happens to still work in R12B, you should correct your code. A future release will adhere to the documentation.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-6983

1.16 Kernel 2.11.5.2

Fixed Bugs and Malfunctions

The kernel parameter dist_auto_connect once could fail to block a node if massive parallel sends were issued during a transient failure of network communication

Own Id: OTP-6893 Aux Id: seq10753

1.17 Kernel 2.11.5.1

Fixed Bugs and Malfunctions

The internal (rarely used) DNS resolver has been modified to not use the domain search list when asked to resolve an absolute name; a name with a terminating dot. There was also a bug causing it to create malformed DNS queries for absolute names that has been corrected, correction suggested by Scott Lystig Fritchie. The code has also been corrected to look up cached RRs in the same search order as non-cached, now allows having the root domain among the search domains, and can now actually do a zone transfer request.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-6806 Aux Id: seq10714 EABln35459
zlib:close/1 would leave an EXIT message in the message queue if the calling process had the trap_exit flag enabled.

Own Id: OTP-6811

Improvements and New Features

The documentation of process_flag(priority, Level) has been updated, see the erlang(3) documentation.

Own Id: OTP-6745 Aux Id: OTP-6715

1.18 Kernel 2.11.5

Fixed Bugs and Malfunctions

The shell has been updated to fix the following flaws: Shell process exit left you with an unresponsive initial shell if not using oldshell. Starting a restricted shell with a nonexisting callback module resulted in a shell where no commands could be used, not even init:stop/0. Fun's could not be used as parameters to local shell functions (in shell_default or user_default) when restricted_shell was active.

Own Id: OTP-6537
The undocumented feature gen_tcp:fdopen/2 was broken in R11B-4. It is now fixed again.

Own Id: OTP-6615
Corrected cancellation of timers in three places in the inet_res module. (Problem found by Dialyzer.)

Own Id: OTP-6676

Improvements and New Features

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
Minor Makefile changes.

Own Id: OTP-6689 Aux Id: OTP-6742
The documentation of process_flag(priority, Level) has been updated, see the erlang(3) documentation.

Own Id: OTP-6715

1.19 Kernel 2.11.4.2

Improvements and New Features

process_flag/2 accepts the new flag sensitive.

Own Id: OTP-6592 Aux Id: seq10555

1.20 Kernel 2.11.4.1

Fixed Bugs and Malfunctions

A bug in gen_udp:open that broke the 'fd' option has been fixed.

Own Id: OTP-6594 Aux Id: seq10619

1.21 Kernel 2.11.4

Fixed Bugs and Malfunctions

Added a warning to the documentation for the error_logger functions error_msg/1,2, warning_msg/1,2 and info_msg/1,2 that calling these function with bad arguments can crash the standard event handler.

Own Id: OTP-4575 Aux Id: seq7693
A bug in inet_db concerning getting the resolver option retry has been corrected.

Own Id: OTP-6380 Aux Id: seq10534
Names registered by calling global:register_name() or global:re_register_name() were not always unregistered when the registering or registered process died. This bug has been fixed.

Own Id: OTP-6428
When setting the kernel configuration parameter error_logger to false, the documentation stated that "No error logger handler is installed". This is true, but error logging is not turned off, as the initial, primitive error logger event handler is kept, printing raw event messages to tty.

Changing this behavior can be viewed as a backward incompatible change. Instead a new value silent for the configuration parameter has been added, which ensures that error logging is completely turned off.

Own Id: OTP-6445
Clarified the documentation for code:lib_dir/1 and code:priv_dir/1. The functions traverse the names of the code path, they do not search the actual directories.

Own Id: OTP-6466
io:setopts returned {error,badarg}, when called with only an expand_fun argument. (Thanks to igwan.)

Own Id: OTP-6508

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 OTP 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
Monitoring of nodes has been improved. Now the following properties apply to net_kernel:monitor_nodes/[1,2]:
- nodeup messages will be delivered before delivery of any message from the remote node passed through the newly established connection.
- nodedown messages will not be delivered until all messages from the remote node that have been passed through the connection have been delivered.
- Subscriptions can also be made before the net_kernel server has been started.
Own Id: OTP-6481
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
Dialyzer warnings have been eliminated.

Own Id: OTP-6523
The documentation for file:delete/1 and file:set_cwd/1 has been updated to clarify what happens if the input arguments are of an incorrect type.

Own Id: OTP-6535

1.22 Kernel 2.11.3.1

Fixed Bugs and Malfunctions

An erroneous packet size could be used for the first messages passed through a newly established connection between two Erlang nodes. This could cause messages to be discarded, or termination of the connection.

Own Id: OTP-6473

1.23 Kernel 2.11.3

Fixed Bugs and Malfunctions

On Unix, the unix:cmd/1 function could leave an 'EXIT' message in the message queue for the calling process That problem was more likely to happen in an SMP emulator.

Own Id: OTP-6368

Improvements and New Features

More interfaces are added in erl_ddll, to support different usage scenarios.

Own Id: OTP-6307 Aux Id: OTP-6234
Locks set by calling global:set_lock() were not always deleted when the locking process died. This bug has been fixed.

Own Id: OTP-6341 Aux Id: seq10445

1.24 Kernel 2.11.2

Fixed Bugs and Malfunctions

Behavior in case of disappeared nodes when using he 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
Start-up problems for the internal process used by the inet:gethostbyname() functions were eliminated. If the internal process (inet_gethost_native) had not previously been started, and if several processes at the same time called one of the inet:gethostbyname() functions, the calls could fail.

Own Id: OTP-6286

Improvements and New Features

Code cleanup: the old internal obsolete file_server has been removed. It was only used when communicating with R7 and older nodes.

Own Id: OTP-6245
Trying to open a non-existent or badly formed disk log no longer results in a crash report. In particular, ets:file2tab/1 reports no error when the argument is not a well-formed disk log file. (The return value has not been changed, it is still an error tuple.)

Own Id: OTP-6278 Aux Id: seq10421
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
To help Dialyzer find more bugs, many functions in the Kernel and STDLIB applications now only accept arguments of the type that is documented.

For instance, the functions lists:prefix/2 and lists:suffix/2 are documented to only accept lists as their arguments, but they actually accepted anything and returned false. That has been changed so that the functions cause an exception if one or both arguments are not lists.

Also, the string:strip/3 function is documented to take a character argument that is a character to strip from one or both ends of the string. Given a list instead of a character, it used to do nothing, but will now cause an exception.

Dialyzer will find most cases where those functions are passed arguments of the wrong type.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-6295

1.25 Kernel 2.11.1.1

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

1.26 Kernel 2.11.1

Fixed Bugs and Malfunctions

In R11B-0, the erl_ddll server process is always started. Despite that, the configuration parameter start_ddll for the Kernel application was still obeyed, which would cause the erl_ddll server to be started TWICE (and the system shutting down as a result). In this release, start_ddll is no longer used and its documentation has been removed.

Own Id: OTP-6163
The kernel option {dist_auto_connect,once} could block out nodes that had never been connected, causing persistent partitioning of networks. Furthermore, partial restarts of networks could cause inconsistent global name databases. Both problems are now solved.

Own Id: OTP-6200 Aux Id: seq10377

Improvements and New Features

Late arriving tcp_closed and udp_closed messages are now removed from the message queue of a process calling gen_tcp:close/1, gen_udp:close/1, and inet:close/1.

Own Id: OTP-6197

1.27 Kernel 2.11

Fixed Bugs and Malfunctions

When repairing a disk log with a corrupt index file (caused by for instance a hard disk failure) the old contents of the index file is kept unmodified. This will make repeated attempts to open the disk log fail every time.

Own Id: OTP-5558 Aux Id: seq9823
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
The behavior when an application fails to start and possibly causes the runtime system to halt has been cleaned up, including fixing some minor bugs.

application_controller should now always terminate with a non-nested string, meaning the slogan in an erl_crash.dump should always be easy to read.

init now makes sure that the slogan passed to erlang:halt/1 does not exceed the maximum allowed length.

Redundant calls to list_to_atom/1 has been removed from the primitive error_logger event handler. (Thanks Serge Aleynikov for pointing this out).

The changes only affects the contents of the error messages and crashdump file slogan.

Own Id: OTP-5964
The erl_ddll server is now started when OTP is started and placed under the Kernel supervisor. This fixes several minor issues. It used to be started on demand.

The documentation for the start and stop functions in the erl_ddll module has been removed, as those functions are not meant to be used by other applications.

Furthermore, the erl_ddll:stop/1 function no longer terminates the erl_ddll server, as that would terminate the entire runtime system.

Own Id: OTP-6033

Improvements and New Features

Removed some unused functions from application_master.

Own Id: OTP-3889
Global no longer allows the registration of a process under more than one name. If the old (buggy) behavior is desired the Kernel application variable global_multi_name_action can be given the value allow.

Own Id: OTP-5640 Aux Id: OTP-5603
The (slightly misleading) warnings that was shown when the erlang.erl file was compiled has been eliminated.

Own Id: OTP-5947
The auth module API is deprecated.

Own Id: OTP-6037
Added erlang:demonitor/2, making it possible to at the same time flush a received 'DOWN' message, if there is one. See erlang(3).

Own Id: OTP-6100 Aux Id: OTP-5772

1.28 Kernel 2.10.13

Fixed Bugs and Malfunctions

Large files (more than 2 GBytes) are now handled on Solaris 8.

Own Id: OTP-5849 Aux Id: seq10157
During startup, a garbage {'DOWN', ...} message was left by inet_gethost_native, that caused problems for the starting code server.

Own Id: OTP-5978 Aux Id: OTP-5974

Improvements and New Features

global now makes several attempts to connect nodes when maintaining the fully connected network. More than one attempt is sometimes needed under very heavy load.

Own Id: OTP-5889
erl_epmd now explicitly sets the timeout to infinity when calling gen_server:call. The old timeout of 15 seconds could time out under very heavy load.

Own Id: OTP-5959
Corrected the start of code server to use reference-tagged tuples to ensure that an unexpected message sent to the parent process does not cause a halt of the system. Also removed the useless start/* functions in both code.erl and code_server.erl and no longer exports the init function from code_server.erl.

Own Id: OTP-5974 Aux Id: seq10243, OTP-5978

1.29 Kernel 2.10.12

Fixed Bugs and Malfunctions

A bug in global has been fixed: the locker process added nonode@nohost to the list of nodes to lock. This could happen before any nodes got known to the global name server. Depending on net configuration the symptom was a delay.

Own Id: OTP-5792 Aux Id: OTP-5563
If an .app file is missing, the error reason returned by application:load/1 has been corrected to {"no such file or directory", "FILE.app"}, instead of the less informative {"unknown POSIX error","FILE.app"}.

Own Id: OTP-5809
Bug fixes: disk_log:accessible_logs/0 no longer reports all pg2 process groups as distributed disk logs; disk_log:pid2name/1 did not recognize processes of distributed disk logs.

Own Id: OTP-5810
The functions file:consult/1, file:path_consult/2, file:eval/1,2, file:path_eval/2,3, file:script/1,2, file:path_script/2,3 now return correct line numbers in error tuples.

Own Id: OTP-5814
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
Minor corrections in the description of open modes. (Thanks to Richard Carlsson.)

Own Id: OTP-5856

Improvements and New Features

application_controller now terminates with the actual error reason, instead of shutdown. This means that the crash dump now should be somewhat more informative, in the case where the runtime system is terminated due to an error in an application.

Example: If the (permanent) application app1 fails to start, the slogan now will be: "Kernel pid terminated (application_controller) ({application_start_failure,app1,{shutdown, {app1,start,[normal,[]]}}})"

rather than the previous "Kernel pid terminated (application_controller) (shutdown)".

Own Id: OTP-5811

1.30 Kernel 2.10.11.1

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(3) 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

Improvements and New Features

Documentation improvements:

- documentation for erlang:link/1 corrected

- command line flag -code_path_cache added

- erl command line flags clarifications

- net_kernel(3) clarifications

Own Id: OTP-5847

1.31 Kernel 2.10.11

Fixed Bugs and Malfunctions

Several bug fixes and improvements in the global name registration facility (see global(3)):
- the name resolving procedure did not always unlink no longer registered processes;
- the global name could sometimes hang when a nodedown was immediately followed by a nodeup;
- global names were not always unregistered when a node went down;
- it is now possible to set and delete locks at the same time as the global name server is resolving names--the handling of global locks has been separated from registration of global names;
As of this version, global no longer supports nodes running Erlang/OTP R7B or earlier.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-5563
The functions global:set_lock/3 and global:trans/4 now accept the value 0 (zero) of the Retries argument.

Own Id: OTP-5737
The inet:getaddr(Addr, Family) no longer validates the Addr argument if it is a 4 or 8 tuple containing the IP address, except for the size of the tuple and that it contains integers in the correct range.

The reason for the change is that validation could cause the following sequence of calls to fail:

{ok,Addr} = inet:getaddr(localhost, inet6), gen_tcp:connect(Addr, 7, [inet6])

Own Id: OTP-5743

Improvements and New Features

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
Added application interface functions which_applications/1, set_env/4 and unset_env/3, which take an additional Timeout argument. To be used in situations where the standard gen_server timeout (5000ms) is not adequate.

Own Id: OTP-5724 Aux Id: seq10083
Improved documentation regarding synchronized start of applications with included applications (using start phases and application_starter).

Own Id: OTP-5754
New socket options priority and tos for platforms that support them (currently only Linux).

Own Id: OTP-5756
The global name server has been optimized when it comes to maintaining a fully connected network.

Own Id: OTP-5770

1.32 Kernel 2.10.10.1

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

1.33 Kernel 2.10.10

Fixed Bugs and Malfunctions

If several processes (at the same node) simultaneously tried to start the same distributed application, this could lead to application:start returning an erroneous value, or even hang.

Own Id: OTP-5606 Aux Id: seq9838

Improvements and New Features

The manual pages for most of the Kernel and some of the STDLIB modules have been updated, in particular regarding type definitions.

The documentation of the return value for erts:info/1 has been corrected.

The documentation for erlang:statistics/1 now lists all possible arguments.

Own Id: OTP-5360
When the native resolver fails a gethostbyaddr lookup, nxdomain should be returned. There should be no attempt to fallback on a routine that succeeds if only the syntax of the IP address is valid. This has been fixed.

Own Id: OTP-5598 Aux Id: OTP-5576
Replaced some tuple funs with the new fun M:F/A construct.

The high-order functions in the lists module no longer accept bad funs under any circumstances. 'lists:map(bad_fun, [])' used to return '[]' but now causes an exception.

Unused, broken compatibility code in the ets module was removed. (Thanks to Dialyzer.)

Eliminated 5 discrepancies found by Dialyzer in the Appmon application.

Own Id: OTP-5633
The possibility to have comments following the list of tuples in a config file (file specified with the -config flag) has been added.

Own Id: OTP-5661 Aux Id: seq10003

1.34 Kernel 2.10.9

Fixed Bugs and Malfunctions

'erl -config sys.config' would fail to start if the sys.config file did not contain any whitespace at all after the dot. (Thanks to Anders Nygren.)

Own Id: OTP-5543
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

Improvements and New Features

At startup, the Erlang resolver hosts table was used to look up the name of the local (and possibly stand alone) host. This was incorrect. The configured resolver method is now used for this purpose.

Own Id: OTP-5393
The erlang:port_info/1 BIF is now documented. Minor corrections of the documentation for erlang:port_info/2.

Added a note to the documentation of the math module that all functions are not available on all platforms.

Added more information about the +c option in the erl man page in the ERTS documentation.

Own Id: OTP-5555
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
According to the documentation global implements the equivalent of register/2, which returns badarg if a process is already registered. As it turns out there is no check in global if a process is registered under more than one name. If some process is accidentaly or by design given several names, it is possible that the name registry becomes inconsistent due to the way the resolve function is called when name clashes are discovered (see register_name/3 in global(3)).

In OTP R11B global will not allow the registration of a process under more than one name. To help finding code where no will be returned, a Kernel application variable, global_multi_name_action, is hereby introduced. Depending on its value (info, warning, or error), messages are sent to the error logger when global discovers that some process is given more than one name. The variable only affects the node where it is defined.

Own Id: OTP-5603

1.35 Kernel 2.10.8

Improvements and New Features

In case of a DNS lookup loop, inet_db:getbyname ends up building an infinite list. This has been fixed.

Own Id: OTP-5449
When doing an inet6 name lookup on an IPv4 address it was possible to get an address on IPv4 format back. This has been corrected. Some other minor inconsistencies regarding IPv6 name lookup have also been corrected.

Own Id: OTP-5576

1.36 Kernel 2.10.7

Fixed Bugs and Malfunctions

Under certain circumstances the net_kernel could emit spurious nodedown messages. This bug has been fixed.

Own Id: OTP-5396
Removed description of the keep_zombies configuration parameter in the kernel man page.

Own Id: OTP-5497

Improvements and New Features

Eliminated Dialyzer warnings (caused by dead code) in the init and prim_file modules.

Own Id: OTP-5496
inet_config now also checks the environment variable ERL_INETRC for a possible user configuration file. See the ERTS User's Guide for details.

Own Id: OTP-5512

1.37 Kernel 2.10.6

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
The possibility to start the Erlang shell in parallel with the rest of the system was reintroduced for backwards compatibility in STDLIB 1.13.1. The flag to be used for this is now called async_shell_start and has been documented. New shells started from the JCL menu are not synchronized with init anymore. This makes it possible to start a new shell (e.g. for debugging purposes) even if the initial shell has not come up.

Own Id: OTP-5406 Aux Id: OTP-5218

1.38 Kernel 2.10.5

Fixed Bugs and Malfunctions

Documentation for erlang:binary_to_float/1 deleted. The BIF itself was removed several releases ago.

Updated documentation for apply/2 and apply/3.

Own Id: OTP-5391

Improvements and New Features

net_kernel:monitor_nodes/2 which takes a flag and an option list has been added. By use of net_kernel:monitor_nodes/2 one can subscribe for nodeup/nodedown messages with extra information. It is now possible to monitor hidden nodes, and get nodedown reason. See the net_kernel(3) documentation for more information.

Own Id: OTP-5374

1.39 Kernel 2.10.4

Fixed Bugs and Malfunctions

The application master for an application now terminates the application faster, which reduces the risk for timeouts in other parts of the system.

Own Id: OTP-5363 Aux Id: EABln19084
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

1.40 Kernel 2.10.3

Improvements and New Features

With the -eval flag (erl -eval Expr), an arbitrary expression can be evaluated during system initialization. This is documented in init(3).

Own Id: OTP-5260
The unsupported and undocumented modules socks5, socks5_auth, socks5_tcp, and socks5_udp have been removed.

Own Id: OTP-5266

1.41 Kernel 2.10.1

Fixed Bugs and Malfunctions

The Pman 'trace shell' functionality was broken and has now been fixed. Furthermore, Pman could not correctly find the pid of the active shell if more than one shell process was running on the node. This has also been corrected.

Own Id: OTP-5191
The documentation for the auth:open/1 function which no longer exists has been removed. (Thanks to Miguel Barreiro.)

Own Id: OTP-5208
Corrected the crc32/3 function in the undocumented and unsupported zlib module.

Own Id: OTP-5227

Improvements and New Features

You can now start Erlang with the -rsh flag which gives you a remote initial shell instead of a local one. Example:
```
            erl -sname this_node -rsh other_node@other_host
          
```
Own Id: OTP-5210
If /etc/hosts specified two hosts with the same IP address (on separate lines), only the last host would be registered by inet_db during inet configuration. This has been corrected now so that both aliases are registered with the same IP address.

Own Id: OTP-5212 Aux Id: seq7128
The documentation for BIFs that take I/O lists have been clarified. Those are list_to_binary/1, port_command/2, port_control/3.

Documentation for all is_* BIFs (such as is_atom/1) has been added.

Removed the documentation for erlang:float_to_binary/2 which was removed from the run-time system several releases ago.

Own Id: OTP-5222