Changes/Erlang 25

Erlang 25

Summary

Update Erlang/OTP to version 25.

Owner

• Name: Peter Lemenkov, Fedora Erlang SIG, Randy Barlow, Jeremy Cline
• Email: lemenkov@gmail.com, erlang@lists.fedoraproject.org, bowlofeggs@fedoraproject.org, jcline@fedoraproject.org

Current status

• Targeted release: Fedora 37
• Last updated: 2022-07-01
• devel thread
• FESCo issue: #2809
• Tracker bug: #2100623
• Release Notes tracker: #851

Detailed Description

Upgrade Erlang to version 25 which brings a lot of changes. Just a few highlights from many:

• The Many-to-One Parallel Signal Sending Optimization.
• Type-Based Optimizations in the JIT.
• New 'maybe' operator.
• The JIT now supports the AArch64 (ARM64) architecture.
• Better support for perf and gdb.
• Better error reporting in some cases.

Aside from this, we plan to further improve quality of Erlang and related packages. These are shortcomings we want to address:

• Finish switching to rebar3 as a main build tool and deprecate rebar2.
  • Improve Erlang Packaging Guidelines according to this switch and promote it as the official guideline.
• Every daemon written in Erlang has its own logging solution which doesn't use neither syslog nor Journald. We should start switching them to unified logger.
• We should allow D-Bus API via erlang-dbus library or any other recent implementations..
• SELinux rules for main Erlang applications (Ejabberd, CouchDB, RabbitMQ) are still outdated or missing.

Benefit to Fedora

Fedora users, both developers and end-users, will have visible benefits from using Fedora-provided packages. Namely:

• Improved scalability and robustness.
• Much easier developing and debugging.

Scope

• Proposal owners:
  • Upgrade Erlang to the latest version (25.0).
  • Every Erlang daemon's systemd unit should require epmd.socket.
  • Upgrade outdated packages:
    • Riak
      • Riak has has been retired. We have to re-add it back.
    • Ejabberd
    • RabbitMQ.
    • CouchDB
      • CouchDB has has been retired. We have to re-add it back.
  • rebar3
  • Package GDB macros for easier coredump debugging (see also this ticket).
• Other developers: N/A
• Release engineering: TBA
• Policies and guidelines:
  • We should promote officially Erlang Packaging Guidelines.
• Trademark approval: N/A (not needed for this Change)

Upgrade/compatibility impact

• Binaries compiled with Erlang 22 and older are no longer compatible.

How To Test

• Ensure that high-grade Erlang applications are still working:

Name	Tested
couchdb	No (package was retired :( )
ejabberd	No
elixir	No
rabbitmq-server	No
riak	No (package was retired :( )
wings	No

• Collect feedback from volunteers regarding their experience with this Erlang/OTP version

User Experience

Users will get more robust, scalable, and fast Erlang applications.

Dependencies

The following packages must be rebuilt: NIF-libraries.

Contingency Plan

• Contingency mechanism: None necessary. Instead of falling back to the previous version we should fix existing packages in order to help the Community. We should also monitor upstream development process for potentially discovered issues and proactively apply patches (as we already did with Erlang R14, Erlang R15, Erlang R16, Erlang 17, Erlang 18, Erlang 19, Erlang 20, Erlang 21, Erlang 22, Erlang 23, and Erlang 24). It should be noted that this change consists from an independent or loosely coupled smaller changes. If we fail to deliver some changes in time, we should reschedule these exact changes to the future Fedora release while keeping already implemented ones.
• Contingency deadline: N/A
• Blocks release? N/A
• Blocks product? N/A

Documentation

• Erlang/OTP 25.0 release notes

Release Notes

Erlang/OTP 25.0 is available in Fedora 37.