A new logging API is added to Erlang/OTP, see the logger(3) manual page, and section Logging in the Kernel User's Guide.

Calls to error_logger are automatically redirected to the new API, and legacy error logger event handlers can still be used. It is, however, recommended to use the Logger API directly when writing new code.

Notice the following potential incompatibilities:

Since Logger is new in Erlang/OTP 21.0, we do reserve the right to introduce changes to the Logger API and functionality in patches following this release. These changes might or might not be backwards compatible with the initial version.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-13295

The old and outdated "Status Inspection" tool (modules si and si_sasl_sup) is removed.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-14469

When creating the release tar file, systools now includes sys.config.src if it exists in the $ROOT/releases/<vsn>/ directory. This is to allow adjustments, e.g. resolving environment variables, after unpacking the release, but before installing it. This functionality requires a custom tool which uses sys.config.src as input and creates a correct sys.config file.

Own Id: OTP-14950 Aux Id: PR-1560

When upgrading with instruction 'restart_new_emulator', the generated temporary boot file used 'kernelProcess' statements from the old release instead of the new release. This is now corrected.

This correction is needed for upgrade to OTP-21.

Own Id: OTP-15017

The Report Browser, rb, could earlier not handle reports that were not lists, for example generated by error_logger:info_report({some, tuple}). This term is allowed as input to error_logger, but rb would state that "A report on bad form was encountered". This is now corrected.

Own Id: OTP-13906 Aux Id: ERL-261

General Unicode improvements.

Own Id: OTP-14462

Files generated by release_handler and reltool, which might contain Unicode characters, are now encoded as UTF-8 and written with format "~tp" or "~ts". If the file is to be read by file:consult/1, an encoding comment is added.

Own Id: OTP-14463

The SASL error logger event handler, sasl_report_file_h, will now by default open its log file with encoding UTF-8. This can be overridden when configuring SASL, see configuration parameter sasl_error_logger in the SASL reference manual.

Own Id: OTP-14618

Documented default values for the 'mod' and 'start_phases' fields in .app files were not allowed as actual values in a .app file. This is now corrected.

Own Id: OTP-14029

Miscellaneous updates due to atoms containing arbitrary Unicode characters.

Own Id: OTP-14285

When both options 'warnings_as_errors' and 'silent' were given to systools:make_script or systools:make_relup, no error reason would be returned if warnings occurred. Instead only the atom 'error' was returned. This is now corrected.

Options 'warnings_as_errors' and 'no_warn_sasl' are now also allowed for systools:make_tar.

Own Id: OTP-14170

code:add_pathsa/1 and command line option -pa both revert the given list of directories when adding it at the beginning of the code path. This is now documented.

Own Id: OTP-13920 Aux Id: ERL-267

Improved dirty scheduler support. A purge of a module can now be performed without having to wait for completion of all ongoing dirty NIF calls.

Note that when enabling support for dirty schedulers, a new purge strategy will as of ERTS version 8.1 be enabled. This new strategy is not fully backwards compatible with the strategy used by default. For more information see the documentation of erlang:check_process_code/3.

Own Id: OTP-13808 Aux Id: OTP-13833

A new purge strategy has been introduced. The new strategy will by default be disabled during the OTP 19 release, but will be the only strategy available as of the OTP 20 release.

The new strategy is slightly incompatible with the strategy being used by default in OTP 19. Using the default strategy, processes holding funs that refer to the module being purged either fail a soft purge, or will be killed during a hard purge. The new strategy completely ignores funs. If funs referring to the code being purged exist, and are used after a purge, an exception will be raised upon usage. That is, the behavior will be exactly the same as the case when a fun is received by a process after the purge.

The new strategy can optionally be enabled when building OTP during OTP 19, and will automatically be enabled if the runtime system is built with support for dirty schedulers.

For more information see the documentation of erlang:check_process_code/3.

Own Id: OTP-13833

The module 'overload' is removed.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-13184

During upgrade, the release_handler collects a list of supervisor pids in order to list all processes in the supervisor tree. If one of the supervisors (legitimately) exits before release_handler can examine it, then sys:get_status/1 would earlier be called with a dead pid, causing a 'noproc' error. This has been corrected.

Own Id: OTP-13291

The module overload is deprecated and will be removed in OTP 19.

Own Id: OTP-13057

Improve implementation of supervisor child count, making it faster and more accurate for dynamic processes of a simple_one_for_one supervisor.

Own Id: OTP-13290

Documentation improvements

Own Id: OTP-13000

A mechanism for limiting the amount of text that the built-in error logger events will produce has been introduced. It is useful for limiting both the size of log files and the CPU time used to produce them.

This mechanism is experimental in the sense that it may be changed if it turns out that it does not solve the problem it is supposed to solve. In that case, there may be backward incompatible improvements to this mechanism.

See the documentation for the config parameter error_logger_format_depth in the Kernel application for information about how to turn on this feature.

Own Id: OTP-12864

The undocumented upgrade instruction {remove_module,PrePurge,PostPurge,DepMods} is removed. This instruction was added for symmetry reasons in OTP R7B, but was never documented or tested.

The existing instruction {add_module,Mod,DepMods} is now documented, and the complementing instruction {delete_module,Mod,DepMods} is added.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-11540

The sasl_error_logger configuration parameter now supports the value {file,FileName,Modes} which allows the log file to be opened in other mode than write (for example, append mode).

Own Id: OTP-12778

The documentation erroneously specified that alarm_handler:clear_alarm/1 would clear all alarms with id AlarmId. This is now corrected according to the implementation - only the latest received alarm with the given AlarmId is cleared by the simple default handler.

Own Id: OTP-12025

The upgrade instruction 'restart_application' would earlier ignore the restart type configured in the .rel file and always restart the application as permanent. This is now changed, and the restart type from the .rel file is used. If restart type is 'load', the application will only be loaded and not started. If the restart type is 'none', the application will not be loaded nor started, but all modules in the application will be loaded. (Thanks to Tobias Schlager for reporting this problem)

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-11716

If systools:make_script/2 failed with reason duplicate_modules, and the silent flag was not used, a crash with reason function_clause would occur when systools tried to format the error message. This has been corrected. (Thanks to Jean-Sébastien Pédron)

Own Id: OTP-11819

Calls to erlang:open_port/2 with 'spawn' are updated to handle space in the command path.

Own Id: OTP-10842

Some more documentation is added to explain the behavior when an upgrade includes new versions of ERTS, Kernel, STDLIB or SASL.

Own Id: OTP-11717

Don't try to add the log_mf_h handler in sasl unless configured to do so. Thanks to Richard Carlsson.

Own Id: OTP-11464

Fix confusing documentation about error handlers in SASL.(Thanks to Richard Carlsson)

Own Id: OTP-11507

A bug in the mechanism for upgrading core parts of Erlang/OTP (emulator, kernel, stdlib, sasl) caused a switch of paths between stdlib and sasl in the intermediate .script/.boot file. The bug was introduces along with this upgrade mechanism in R15B. It has now been corrected. (Thanks to Tobias Schlager)

Own Id: OTP-11529

Added a boot file which skips loading the "$HOME/.erlang" file on startup. Enable by starting erlang with "erl -boot no_dot_erlang".

*** INCOMPATIBILITY with false ***

Own Id: OTP-8479 Aux Id: seq11510

Add Fd usage in rb logging. Thanks to Eric Pailleau.

Own Id: OTP-11252

Fix receive support in erl_eval with a BEAM module. Thanks to Anthony Ramine.

Own Id: OTP-11137

Some updates are made to systools and release_handler for handling of unicode.

Own Id: OTP-10782

release_handler_SUITE:otp_9864 deleted parts of the release_handler_SUITE_data directory so the test suite could not be executed twice without re-installation. This has been corrected.

Own Id: OTP-10394 Aux Id: kunagi-187 [98]

It is no longer possible to have {Mod,Vsn} in the 'modules' list in a .app file.

This was earlier possible, although never documented in the .app file reference manual. It was however visible in the documentation of application:load/[1,2], where the same term as in a .app file can be used as the first argument.

The possibility has been removed since the Vsn part was never used.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-10417

release_handler:upgrade_script and release_handler:downgrade_script could not read appup files with regexps. This has been corrected. (Thanks to Ulf Wiger)

Own Id: OTP-10463

Where necessary a comment stating encoding has been added to Erlang files. The comment is meant to be removed in Erlang/OTP R17B when UTF-8 becomes the default encoding.

Own Id: OTP-10630

If sys.config existed, but was not readable or parseable, this would not be detected until after the upgrade and at the next node restart. The possibility for this to happen is now reduced by adding a check to systools:make_tar which fails the creation of the tar file if sys.config or relup does not have reasonable contents. Note that there are no detailed checks, only parsing and erlang term format check.

Own Id: OTP-9539

systools:make_script would allow {kernel,Vsn,load} in the .rel file, causing a .boot file which only loaded kernel and did not start it. This has been corrected. Only start type 'permanent', which is the default, is now allowed for kernel and stdlib.

Own Id: OTP-9652

release_handler:remove_release/1 now handles symlinked files properly

Own Id: OTP-9864

If stdlib was stated with a start type different from permanent in a .rel file, systools would incorrectly say that sasl had faulty start type. This has been corrected.

Own Id: OTP-9888

Sasl documentation earlier said that the InclApps parameters in a .rel file defaults to the empty list. This is not correct. It defaults to the same value as specified in the .app file. This has been corrected.

Own Id: OTP-9980

Applications that are listed in {applications,Apps} in the .app file were not sorted correctly by systools:make_script/1,2. They got the reverse order of how they were listed in the .app file. This is corrected so they are now sorted (internally between each other) in the same order as they are listed in the .rel file (i.e. the order they are listed in the .app file does no longer matter).

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-9984

Documentation of .appup files now also states that UpFromVsn and DownToVsn can be specified as regular expressions in order to avoid duplicated upgrade instructions.

Own Id: OTP-10001

Reltool would sometimes generate a .app file containing {start_phases,undefined}, which would cause an exception in systools at parse time. This has been corrected so reltool now omits the start_phases entry if the value is undefined. (Thanks to Juan Jose Comellas)

In order to align with reltool, sasl will also omit start_phases entries with value undefined in .script files.

Own Id: OTP-10003

Fix the mechanism for upgrading emulator.

The appup files for kernel, stdlib and sasl do now recognize two major releases back and include a 'restart_new_emulator' instruction.

Appup files can include regular expressions for matching earlier releases.

The mechanism for upgrading the emulator is changed so 'restart_new_emulator' will be the first instruction executed. The rest of the upgrade instruction will be executed after the emulator restart.

A new upgrade instruction 'restart_emulator' is added for the case where the emulator shall be restarted after all other upgrade instructions.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-9438

Add release_handler:which_releases/1

This is an extension to which_releases that allows a user to specify the status of the releases they wish to be returned. For instance it allows for quickly determining which release is 'permanent' without the need of parsing the entire release list. (Thanks to Joe Williams)

Own Id: OTP-9717

Add copy of rel file in releases/Vsn in release tar file

systool:make_tar stores the rel file in the releases directory. When unpacking with release_handler:unpack_release, the file is automatically moved to releases/Vsn/. If, however, the tar file is unpacked manually, the rel file might not be moved, and the next release unpacked might overwrite the rel file. To overcome this, systools:make_tar now stores a copy of the rel file in releases/Vsn/ directly and it is not longer necessary to move the file after unpacking.

The reason for keeping the file in the releases directory also is that is needs to be extracted separately before the release version (Vsn) is known.

Own Id: OTP-9746

The release_handler functionality on windows services was broken. This has been corrected.

Own Id: OTP-9306

If a new version of an application did not include any erlang module changes, the code path of the application was not updated by the release_handler unless a 'load_object_code' instruction was added for the application. This would be a problem if e.g. only some files in the priv dir were changed since calls to code:lib_dir or code:priv_dir would then point to the old location of the application. This has been corrected - now code:replace_path/2 will be called for all applications that are changed (i.e. when the application's vsn is changed in the .rel file).

Own Id: OTP-9402

The appup instruction 'delete_module' would cause a crash during upgrade if the module to be deleted was not loaded. This has been corrected.

Own Id: OTP-9417

If a path was given as ONLY 'ebin' and not for example './ebin', then systools:make_tar would fail with a function_clause exception in filename:join/1. This has been corrected. (Thanks to Nikola Skoric for reporting).

Own Id: OTP-9507

Implement or fix -Werror option

If -Werror is enabled and there are warnings no output file is written. Also make sure that error/warning reporting is consistent. (Thanks to Tuncer Ayaz)

Own Id: OTP-9536

Improved error information for timeouts during release_handler:install_release.

This patch addresses two cases where a timeout will occur during upgrade. 1) if a supervisor is suspended (call to get children from supervisor will hang) 2) if the child spec for a supervisor incorrectly states that it is a worker with a dynamic set of modules (call to get modules from gen_event will hang)

An error report will now be printed, and the return value of release_handler:install_release will indicate what happened. (Thanks to joe williams)

Own Id: OTP-9546

release_handler:install_release could be very slow when there are many processes in the system. Some optimization work has been done both in erts and in the release handler in order to improve this.

A new option, purge, is added to release_handler:check_install_release which can be called first in order to speed up the execution of release_handler:install_release.

Own Id: OTP-9395

Remove traces of release_handler reading from filesystem when it has Masters list

There are a couple of places in release_handler and release_handler_1 that assumed it has a disk to read from, which in the case of an erl_prim_loader Loader other than efile is not necessarily true

Add check_paths/2 to do the equivalent of check_path/1 for when there is a Masters list

Change get_vsn to no longer get sent File paths but instead use the Bin since beam_lib:version being sent a file path causes it to read the local file system

Add get_current_vsn/1 as an equivalent to beam_lib:version(code:which(Mod)), but using erl_prim_loader:get_file instead of reading from local file system

(Thanks to Steven Gravell)

Own Id: OTP-9142

rb:stop did sometimes return {error,running}. This came from supervisor:delete_child and happened when the rb_server has not yet terminated when this function was called. Instead of having a separate gen_server call to rb_server for stopping the process, supervisor:terminate_child is now called. This is a synchronous function - i.e. it waits for the process to actually terminate before it returns.

A file descriptor leak in rb:scan_files is corrected. The index file was never closed after reading.

A mismatch in the behavior of rb:filter, when filter included 'no', is corrected. Such filters will now return *all* non-matching reports, not only the 'proplist' reports.

Own Id: OTP-9149

Start and end date for rb:filter/2 was specified as {{Y-M-D},...} in the help text instead of {{Y,M,D},...}. This has been corrected.

Own Id: OTP-9166

If some, but not all, of the sasl environment variables related to the log_mf_h error handler were missing sasl would successfully start but silently skip starting log_mf_h. This is corrected so sasl startup will now fail if one or two of the three variables are given. If none of the variables are given, sasl will start as before without starting log_mf_h.

Own Id: OTP-9185

Change default behaviour to not check src code when creating release

Add new option src_tests to systools:make_script and systools:make_tar. The old option no_module_tests is now ignored as this is the default behaviour.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-9146 Aux Id: seq11803

Honor start type in .rel files when building relup files

Previously, relup file always included an application:start(Application, permanent) apply instruction for every application that appear in the UpTo/DowFrom release file, whatever their start type in the release file.

The new implementation fixes this bug by honoring the start type according to the rel(5) format. If the start type is none, no apply line is included in the relup. If the start type is load, the relup includes instruction to only load the application. Otherwise, the relup includes an instruction to start the application to the according type.

The fix is implemented by adding a new parameter to the add_application high level appup instruction. This new parameter is documented in appup(5).

Own Id: OTP-9097

In R13B04 sys:get_status was modified to invoke format_status/2 in the callback module if the module exports that function. This resulted in a change to the term returned from calling sys:get_status on the supervisor module, since supervisor is a gen_server and gen_server exports format_status. The sasl release_handler_1 module had a dependency on the pre-R13B04 term returned by sys:get_status when invoked on a supervisor, so the R13B04 change broke that dependency.

This problem has been fixed by change release_handler_1 to handle both the pre-R13B04 and R13B04 terms that sys:get_status can return from a supervisor.

Own Id: OTP-8619 Aux Id: seq11570

Use an infinity timeout in all calls to gen_server:call() in the SASL application.

Own Id: OTP-8506 Aux Id: seq11509

The re:grep/1 function now uses the 're' module instead of the deprecated 'regexp' module. There are new functions rb:filter/1 and rb:filter/2 for easier filtering of reports. (Thanks to Alvaro Videla.)

Own Id: OTP-8443

There is new function sasl_report:format_report/3 that works like the existing sasl_report:write_report/3 function except that it returns a formatted string. Note that there is currently no documentation for the sasl_report module. (Thanks to Jay Nelson.)

Own Id: OTP-8445

Cleanups suggested by tidier and modernization of types and specs.

Own Id: OTP-8455

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 Windows utility Erlsrv, run in interactive mode now accepts options for registering internal service name and description field of Windows registry database.

Own Id: OTP-8132

When using the SASL application configuration parameter masters the error tuple {error,{no_such_file,{Master,FileName}}} was sometimes returned even though the file FileName existed.

Own Id: OTP-7667

Missing preloaded modules added

Own Id: OTP-7820

A Dialyzer warning was eliminated

Own Id: OTP-7635

Minor changes.

Own Id: OTP-7388

Minor updates.

Own Id: OTP-6998

Minor Makefile changes.

Own Id: OTP-6689

Obsolete guard tests (such as list()) have been replaced with the modern guard tests (such as is_list()).

Own Id: OTP-6725

Removed some dead code from erlsrv:get_service/2, release_handler:do_write_file/2, systools_relup:foreach_baserel_up/7 and systools_relup:foreach_baserel_dn/7.

Own Id: OTP-6499

Added an option {outdir,Dir} to the functions in systools, making it possible to specify in which directory a boot script, relup file or release package file should be placed.

Also, when using systools:make_tar/2 to create a release package file, the boot script, relup file and sys.config are now searched for also in the current working directory and any directory specified by the path option, not only in the directory of the .rel file.

As part of the work some minor bugs have been corrected:

Own Id: OTP-6226

release_handler:upgrade_app/2 and release_handler:downgrade_app/2,3 -- used for testing application upgrade and downgrade according to the .appup file -- now update application configuration parameters correctly. (Thanks to Serge Aleynikov)

Own Id: OTP-6162

Fixed some minor bugs in release_handler found by Dialyzer.

Own Id: OTP-6039

Added a number of functions to release_handler which makes it possible to test upgrade and downgrade of applications according to an .appup file "on the fly":

- upgrade_app/2

- upgrade_script/2

- downgrade_app/2,3

- downgrade_script/3

- eval_appup_script/4

Own Id: OTP-5858

A new option {update_paths,Bool} has been added for release_handler:install_release/2. It indicates if all application code paths should be updated (Bool==true), or if only code paths for modified applications should be updated (Bool==false, default).

release_handler:set_unpacked/2 now returns an error tuple if a specified application directory does not exist.

*** POTENTIAL INCOMPATIBILITY ***

Own Id: OTP-5761

A bug that made it impossible to call rb:show(N) (N being an integer) twice without getting an error has been fixed.

Own Id: OTP-5287