ERTS Release Notes

## 1 ERTS Release Notes

This document describes the changes made to the ERTS application.

### 1.1 Erts 5.5.3

#### 1.1.1 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

#### 1.1.2 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(1)`.
  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(3)` 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

### 1.2 Erts 5.5.2.2

#### 1.2.1 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

### 1.3 Erts 5.5.2.1

#### 1.3.1 Fixed Bugs and Malfunctions

- The run_erl program now aquires its psedo-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

### 1.4 Erts 5.5.2

#### 1.4.1 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 operationes 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

#### 1.4.2 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 comparision, 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

### 1.5 Erts 5.5.1.1

#### 1.5.1 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

### 1.6 Erts 5.5.1

#### 1.6.1 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 it's 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

#### 1.6.2 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(1)` 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

### 1.7 ERTS 5.5

#### 1.7.1 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

#### 1.7.2 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 thruly 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(1)` 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(1)` man page.
  *** POTENTIAL INCOMPATIBILITY ***
  Own Id: OTP-6095 Aux Id: OTP-6006

### 1.8 ERTS 5.4.13

#### 1.8.1 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 exeption reason that had occured 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

#### 1.8.2 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 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

### 1.9 ERTS 5.4.12

#### 1.9.1 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

#### 1.9.2 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

### 1.10 ERTS 5.4.11

#### 1.10.1 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
- `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

#### 1.10.2 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(3)` clarifications
  Own Id: OTP-5847

### 1.11 ERTS 5.4.10

#### 1.11.1 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

#### 1.11.2 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

### 1.12 ERTS 5.4.9.2

#### 1.12.1 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

### 1.13 ERTS 5.4.9.1

#### 1.13.1 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 descritport 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

### 1.14 ERTS 5.4.9

#### 1.14.1 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

#### 1.14.2 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

### 1.15 ERTS 5.4.8

#### 1.15.1 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

#### 1.15.2 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 articially 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

### 1.16 ERTS 5.4.7

#### 1.16.1 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

#### 1.16.2 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

### 1.17 ERTS 5.4.6

#### 1.17.1 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

#### 1.17.2 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

### 1.18 ERTS 5.4.5

#### 1.18.1 Fixed Bugs and Malfunctions

- If a process had node links (created by `monitor_node/2`), excuting `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

#### 1.18.2 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

### 1.19 ERTS 5.4.4

#### 1.19.1 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

#### 1.19.2 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

### 1.20 ERTS 5.4.3

#### 1.20.1 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

#### 1.20.2 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

### 1.21 ERTS 5.4.2.1

#### 1.21.1 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

### 1.22 ERTS 5.4.2

#### 1.22.1 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

### 1.23 ERTS 5.4.1

#### 1.23.1 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 refered 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

#### 1.23.2 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

Copyright © 1991-2007 Ericsson AB