Erts Release Notes

Erts 5.0.1 (R7B)

Improvements and new features

• A new better and more portable hash BIF, erlang:phash/2, has been introduced. The dets module will use the erlang:phash/2 for newly created tables. To rebuild an old table and start to use the new hash BIF, give the {repair,force} option to dets:open_file/2. See the documentation.
  Own Id: OTP-3397
• The -detached flag has been documented in the erl man page. Some other minor documenation errors were also corrected.
  Own Id: OTP-3686
• Function c:memory/[0,1] added. It can be used to retrieve current memory allocation status, see the documentation of the c module.
  Own Id: OTP-3698

Erts 5.0 (R7A)

Known problems

• System enters unstable state if epmd crashes
  Own Id: OTP-1067
  Aux Id: tir-f-054

Fixed errors and malfunctions

• Windows: Some scrollbar problems in Werl were fixed.
  Own Id: OTP-3560
• The BIFs split_binary/2 and binary_to_list/3 did not accept positions greater than 134217727 (128Mb - 1). This has been corrected.
  Own Id: OTP-3594
• Calling binary_to_term/1 on a term which contains several funs could cause an emulator crasch. This has been corrected.
  Own Id: OTP-3644

Improvements and new features

• We have made several changes to the garbage collector and internal memory allocation routines to reduce memory consumption and memory fragmentation. Also, the compiler now makes sure that references to any data that will not be used again will be killed, so that the garbage collector can discard it as soon as possible. (Thanks to Claes Wickstrom at Bluetail who suggested most of the changes to the garbage collector.)
  Own Id: OTP-2375
  Aux Id: seq 816, HA81951
• There now exists syntax for constructing and matching binaries. For more infomation, see Extensions to Erlang. Also, the handling of small binaries (up to 64 bytes) has been optimised, as well as splitting of binaries.
  Own Id: OTP-3376
• The maximum number of ports that can be opened using erlang:open_port/2 can now be configured using the environment variable ERL_MAX_PORTS. By default, the maximum number of ports is 1024. Note that the default value of 1024 in rare cases may be lower than the default value in previous releases (it used to be the maximum number of file descriptors for the current process on Unix).
  (*** INCOMPATIBILITY with R6 ***)
  Own Id: OTP-3494
• The new BIF erlang:read_timer/1 returns the remaining time (in ms) for a timer started by start_timer/3 or send_after/3.
  Own Id: OTP-3495
• Call tracing is greatly improved. It is now possible to trace local function calls (and calls to local functions) set up with the erlang:trace_pattern BIF. Trace compilation for local call is no longer needed.
  Own Id: OTP-3518
• There is now support for operating system threads in drivers. The file driver has been modified to make use of this, which means that lengthy file operations no longer cause everything on the node to pause. Currently only supported on Solaris and Windows. The number of threads in the thread pool can be set with the emulator system flag -A. The default number of threads is 0, which means that this feature is turned off. The number of threads in a node can be obtained by the call erlang:info(thread_pool_size).
  Own Id: OTP-3599
• The BIF erlang:monitor(process, Proc) has been extended to accept named processes, local and remote. See the documentation for erlang:monitor/2 and erlang:demonitor/1.
  Own Id: OTP-3657
• The inet driver (inet_drv, i.e the driver for (TCP&UDP)/IP) and a lot of supporting Erlang code in the application kernel, has been replaced. The new code, courtesy of Tony Rogvall, eliminates one data relay process per socket and thereby gives a throughput boost.
  Own Id: OTP-3661
• Thanks to the HiPE project at Uppsala University, the Erlang emulator now uses a 2 bit tag scheme internally. This change is not visible at the language level, but it means that the Erlang emulator can now address the entire 4Gb address space (OTP R6 could only address 1Gb).
  Own Id: OTP-3667
• The erlang:info/1 and erlang:system_info/1 BIFs have been merged into one. The recommended way to use the combined BIF is by the name erlang:system_info/1, but erlang:info/1 will also work.
  Own Id: OTP-3669
• In Unix, there was once a problem running the erlang emulator as part of a pipeline or with redirected input and/or output. An earlier OTP release introduced the infamous "cat process" which partly solved the problem, but introduced its own new problems. In this version, the internal cat process has been removed in favour of a cleaner solution without any unpleasant side-effects.
  Own Id: OTP-3671
• The beam emulator now uses the C library function call poll() instead of select() on Unix systems that support this, e.g Solaris. On those systems the datatype fd_set no longer limits the number of fildescriptor.
  Own Id: OTP-3673
• New socket options for TCP/IP sockets: 'tpkt' and 'line'. See the documentation for inet:setopts/2.
  Own Id: OTP-3674
• Most of the previously undocumented BIFs in the erlang module have been documented. Still undocumented are BIFs which are of no use in applications, for instance the set of BIFs used to implement the distribution protocol. The newly documented BIFs are:
  append_element/2, bump_reductions/1, display/1, function_exported/3, garbage_collect/0,1, is_builtin/3, loaded/0, make_tuple/2, md5/1, md5_final/1, md5_init/1, md5_update/2, port_close/1, port_command/2, port_connect/2, port_control/3, port_to_list/1, ref_to_list/1, system_info/1, and yield/0.
  Own Id: OTP-3675
• The new BIF term_to_binary/2 can be used for automatically compressing the external representation of an Erlang term. The binary_to_term/1 BIF in R7 automatically recognises and decompresses such compressed terms.
  Own Id: OTP-3676