Ruby 3.3.0-preview1 Released

We are pleased to announce the release of Ruby 3.3.0-preview1. 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


  • Significant performance improvements over 3.2
    • Splat and rest arguments support has been improved.
    • Registers are allocated for stack operations of the virtual machine.
    • More calls with optional arguments are compiled.
    • Integer#!=, String#!=, Kernel#block_given?, Kernel#is_a?, Kernel#instance_of?, Module#=== are specially optimized.
    • Instance variables no longer exit to the interpreter with megamorphic Object Shapes.
  • Metadata for compiled code uses a lot less memory.
  • Improved code generation 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
  • Exit tracing option now supports sampling
    • --trace-exits-sample-rate=N
  • Multiple bug fixes

Other Notable New Features


Performance improvements

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

Other notable changes since 3.2

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

The following default gems are updated.

  • RubyGems
  • bigdecimal 3.1.4
  • bundler
  • csv 3.2.7
  • fiddle 1.1.2
  • fileutils 1.7.1
  • irb 1.6.4
  • optparse 0.4.0.pre.1
  • psych 5.1.0
  • reline 0.3.3
  • stringio 3.0.7
  • strscan 3.0.7
  • syntax_suggest 1.0.4
  • time 0.2.2
  • timeout 0.3.2
  • uri 0.12.1

The following bundled gems are updated.

  • minitest 5.18.0
  • rbs 3.1.0
  • typeprof 0.21.7
  • debug 1.8.0

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, 1922 files changed, 75283 insertions(+), 44896 deletions(-) since Ruby 3.2.0!



    SIZE: 20428213
    SHA1: 5445eec1cd9ddb44e03e74568cac94209c91b42d
    SHA256: c3454a911779b8d747ab0ea87041030d002d533edacb2485fe558b7084da25ed
    SHA512: 0f891f140ddc6372aa7c4459f8784126e0c341db7b80e72c51e441c5153c43c2d7b965f7807c076862ac84b9b8b0c6a66bbf66fc341746016151397bb21c782a

    SIZE: 15074600
    SHA1: 4c22ebca287c87811e1050bf4d59b7d32255b212
    SHA256: ae300b49e06c13087dd163b97eddd38db895dc8e0c9904284119795d75303fbb
    SHA512: 46c1134dba5810847f7f6b4298900a91f5225679d7873548b271f4ef2ad1dc168722562a2e468a2ccf136314176ee613d8c7792fd4411a3f7a44c80b93b417ee

    SIZE: 24846962
    SHA1: 31774fa653c54107b6afc30adda3a0350d8f41d2
    SHA256: 6ecafecf83f2cacf446b2326012f2b6ee1a0614d8dd29bb1fb3f105c27e2c553
    SHA512: 794bef847fefbbdbbdced85975a00c9289ef6464810408af3f0f2055052d6b5ef5576dbd41e0d87bb73f1ad276d8e27c36018610f8e2b9936828c0e692f611f0

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.