Ruby 3.3.0-preview2 Released

We are pleased to announce the release of Ruby 3.3.0-preview2. Ruby 3.3 adds a new pure-Ruby JIT compiler named RJIT, uses Lrama as a parser generator, and many performance improvements especially YJIT.


  • Introduced a pure-Ruby JIT compiler RJIT and replaced MJIT.
    • RJIT supports only x86_64 architecture on Unix platforms.
    • Unlike MJIT, it doesn’t require a C compiler at runtime.
  • RJIT exists only for experimental purposes.
    • You should keep using YJIT in production.
  • If you are interested in developing JIT for Ruby, please check out k0kubun’s presentation on Day 3 of RubyKaigi.

Use Lrama instead of Bison


  • Major performance improvements over 3.2
    • Support for splat and rest arguments has been improved.
    • Registers are allocated for stack operations of the virtual machine.
    • More calls with optional arguments are compiled.
    • Exception handlers are also compiled.
    • Instance variables no longer exit to the interpreter with megamorphic Object Shapes.
    • Unsupported call types no longer exit to the interpreter.
    • Integer#!=, String#!=, Kernel#block_given?, Kernel#is_a?, Kernel#instance_of?, Module#=== are specially optimized.
    • Now more than 3x faster than the interpreter on optcarrot!
  • Metadata for compiled code uses a lot less memory.
  • Generate more compact code on ARM64
  • Option to start YJIT in paused mode and then later enable it manually
    • --yjit-pause and RubyVM::YJIT.resume
    • This can be used to enable YJIT only once your application is done booting
  • ratio_in_yjit stat produced by --yjit-stats is now available in release builds, a special stats or dev build is no longer required.
  • Exit tracing option now supports sampling
    • --trace-exits-sample-rate=N
  • More thorough testing and multiple bug fixes

Other Notable New Features


Performance improvements

  • defined?(@ivar) is optimized with Object Shapes.

Other notable changes since 3.2


IRB has received several enhancements, including but not limited to:

  • Advanced irb:rdbg integration that provides an equivalent debugging experience to pry-byebug (doc).
  • Pager support for commands like ls and show_cmds.
  • More accurate and helpful information provided by the ls and show_source commands.

In addition, IRB has also undergone extensive refactoring and received dozens of bug fixes to facilitate easier future enhancements.

Compatibility issues

Note: Excluding feature bug fixes.

Removed constants

The following deprecated constants are removed.

Removed methods

The following deprecated methods are removed.

Stdlib compatibility issues

ext/readline is retired

  • We have reline that is pure Ruby implementation compatible with ext/readline API. We rely on reline in the future. If you need to use ext/readline, you can install ext/readline via with gem install readline-ext.
  • We no longer need to install libraries like libreadline or libedit.

C API updates

Updated C APIs

The following APIs are updated.

Removed C APIs

The following deprecated APIs are removed.

Standard library updates

RubyGems and Bundler warn if users require gem that is scheduled to become the bundled gems in the future version of Ruby.

The following default gems are updated.

  • RubyGems
  • bigdecimal 3.1.4
  • bundler
  • csv 3.2.8
  • erb 4.0.3
  • fiddle 1.1.2
  • fileutils 1.7.1
  • irb 1.7.4
  • nkf 0.1.3
  • optparse 0.4.0.pre.1
  • psych 5.1.0
  • reline 0.3.8
  • stringio 3.0.9
  • strscan 3.0.7
  • syntax_suggest 1.1.0
  • time 0.2.2
  • timeout 0.4.0
  • uri 0.12.2
  • yarp 0.9.0

The following bundled gems are updated.

  • minitest 5.19.0
  • test-unit 3.6.1
  • rexml 3.2.6
  • rss 0.3.0
  • net-imap 0.3.7
  • rbs 3.2.1
  • typeprof 0.21.8
  • debug 1.8.0

The following default gem is now bundled.

  • racc 1.7.1

See GitHub releases like Logger or changelog for details of the default gems or bundled gems.

See NEWS or commit logs for more details.

With those changes, 4970 files changed, 239635 insertions(+), 165275 deletions(-) since Ruby 3.2.0!



    SIZE: 21074209
    SHA1: cf7329019235dc36b8e3f382a8b8b744922b1163
    SHA256: 30ce8b0fe11b37b5ac088f5a5765744b935eac45bb89a9e381731533144f5991
    SHA512: 1c5a13e519e8487fd40d932b96d14fa729521925c288e7841ab5eada628e506ceca2605bae36eea1aa505d9253383d53cd933b7a4bff96e6de5b1130c7c558e6

    SIZE: 15600992
    SHA1: 606d6423137a24eef4f6b07d167596b63c7aaa17
    SHA256: 62b1c4f586c70bf1cb58f2d909d0d824506315782e835f9dd3fcc0b659a70fc1
    SHA512: 5ff609a66b7359006df0d87477cf70e6e26c5f40ced81b8254f8154f4fc82c77fed297471b55706c1a4466f2a4257999e933b2ed085f695ace265757ab9500a2

    SIZE: 26095651
    SHA1: 4441cd0db23d133e6e2f7dea28f931a68dac6ca5
    SHA256: c9771d24c9b1eab532c04ed076087285601693e4d1c63f131fd078c47c5c0cea
    SHA512: bfeed21d011f891fe22510fe7242992c98f7fd2ce863d8be5740f56a34b726134cb3f5304e8b2dcd468fbc939648f10aae482eee15c1bf6c64b705484ed9e197

What is Ruby

Ruby was first developed by Matz (Yukihiro Matsumoto) in 1993, and is now developed as Open Source. It runs on multiple platforms and is used all over the world especially for web development.