[ruby-core:115887] Ruby 3.3.0 Released

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

## Prism

* Introduced [the Prism parser](https://github.com/ruby/prism) as a default gem
    * Prism is a portable, error tolerant, and maintainable recursive
descent parser for the Ruby language
* Prism is production ready and actively maintained, you can use it in
place of Ripper
    * There is [extensive
documentation](https://ruby.github.io/prism/) on how to use Prism
    * Prism is both a C library that will be used internally by CRuby
and a Ruby gem that can be used by any tooling which needs to parse
Ruby code
    * Notable methods in the Prism API are:
        * `Prism.parse(source)` which returns the AST as part of a
parse result object
        * `Prism.parse_comments(source)` which returns the comments
        * `Prism.parse_success?(source)` which returns true if there
are no errors
* You can make pull requests or issues directly on [the Prism
repository](https://github.com/ruby/prism) if you are interested in
contributing
* You can now use `ruby --parser=prism` or `RUBYOPT="--parser=prism"`
to experiment with the Prism compiler. Please note that this flag is
for debugging only.

## Use Lrama instead of Bison

* Replace Bison with [Lrama LALR parser
generator](https://github.com/ruby/lrama) [[Feature
#19637]](https://bugs.ruby-lang.org/issues/19637)
  * If you have interest, please see [The future vision of Ruby
Parser](https://rubykaigi.org/2023/presentations/spikeolaf.html)
  * Lrama internal parser is replaced with LR parser generated by Racc
for maintainability
  * Parameterizing Rules `(?, *, +)` are supported, it will be used in
Ruby parse.y

## YJIT

* Major performance improvements over Ruby 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.
  * Unsupported call types and megamorphic call sites no longer exit
to the interpreter.
  * Basic methods like Rails `#blank?` and
    [specialized
`#present?`](https://github.com/rails/rails/pull/49909) are inlined.
  * `Integer#*`, `Integer#!=`, `String#!=`, `String#getbyte`,
    `Kernel#block_given?`, `Kernel#is_a?`, `Kernel#instance_of?`, and
`Module#===`
    are specially optimized.
  * Compilation speed is now slightly faster than Ruby 3.2.
  * Now more than 3x faster than the interpreter on Optcarrot!
* Significantly improved memory usage over Ruby 3.2
    * Metadata for compiled code uses a lot less memory.
    * `--yjit-call-threshold` is automatically raised from 30 to 120
      when the application has more than 40,000 ISEQs.
    * `--yjit-cold-threshold` is added to skip compiling cold ISEQs.
    * More compact code is generated on Arm64.
* Code GC is now disabled by default
  * `--yjit-exec-mem-size` is treated as a hard limit where
compilation of new code stops.
  * No sudden drops in performance due to code GC.
    Better copy-on-write behavior on servers reforking with
    [Pitchfork](https://github.com/shopify/pitchfork).
  * You can still enable code GC if desired with `--yjit-code-gc`
* Add `RubyVM::YJIT.enable` that can enable YJIT at run-time
  * You can start YJIT without modifying command-line arguments or
environment variables.
    Rails 7.2 will [enable YJIT by
default](https://github.com/rails/rails/pull/49947)
    using this method.
  * This can also be used to enable YJIT only once your application is
    done booting. `--yjit-disable` can be used if you want to use other
    YJIT options while disabling YJIT at boot.
* More YJIT stats are available by default
  * `yjit_alloc_size` and several more metadata-related stats are now
available by default.
  * `ratio_in_yjit` stat produced by `--yjit-stats` is now available
in release builds,
    a special stats or dev build is no longer required to access most stats.
* Add more profiling capabilities
  * `--yjit-perf` is added to facilitate profiling with Linux perf.
  * `--yjit-trace-exits` now supports sampling with
`--yjit-trace-exits-sample-rate=N`
* More thorough testing and multiple bug fixes

## RJIT

* 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](https://rubykaigi.org/2023/presentations/k0kubun.html#day3).

## M:N thread scheduler

* M:N thread scheduler was introduced. [[Feature
#19842]](https://bugs.ruby-lang.org/issues/19842)
  * M Ruby threads are managed by N native threads (OS threads) so the
thread creation and management cost are reduced.
  * It can break C-extension compatibility so that M:N thread
scheduler is disabled on the main Ractor by default.
      * `RUBY_MN_THREADS=1` environment variable enables M:N threads
on the main Ractor.
      * M:N threads are always enabled on non-main Ractors.
  * `RUBY_MAX_CPU=n` environment variable sets maximum number of `N`
(maximum number of native threads). The default value is 8.
      * Since only one Ruby thread per Ractor can run at the same
time, the number of native threads will be used, which is the smaller
of the number specified in `RUBY_MAX_CPU` and the number of running
Ractors. So that single Ractor applications (most of applications)
will only use 1 native thread.
      * To support blocking operations, more than `N` native threads
can be used.

## Performance improvements

* `defined?(@ivar)` is optimized with Object Shapes.
* Name resolution such as `Socket.getaddrinfo` can now be interrupted
(in environments where pthreads are available). [[Feature
#19965]](https://bugs.ruby-lang.org/issues/19965)
* Several performance improvements to the Garbage Collector
  * Young objects referenced by old objects are no longer immediately
      promoted to the old generation. This significantly reduces the
frequency of
      major GC collections. [[Feature
#19678]](https://bugs.ruby-lang.org/issues/19678)
  * A new `REMEMBERED_WB_UNPROTECTED_OBJECTS_LIMIT_RATIO` tuning variable was
      introduced to control the number of unprotected objects cause a major GC
      collection to trigger. The default is set to `0.01` (1%). This
significantly
      reduces the frequency of major GC collection. [[Feature
#19571]](https://bugs.ruby-lang.org/issues/19571)
  * Write Barriers were implemented for many core types that were missing them,
      notably `Time`, `Enumerator`, `MatchData`, `Method`,
`File::Stat`, `BigDecimal`
      and several others. This significantly reduces minor GC
collection time and major
      GC collection frequency.
  * Most core classes are now using Variable Width Allocation, notably
`Hash`, `Time`,
      `Thread::Backtrace`, `Thread::Backtrace::Location`,
`File::Stat`, `Method`.
      This makes these classes faster to allocate and free, use less
memory and reduce
      heap fragmentation.
  * Support for weak references has been added to the garbage
collector. [[Feature #19783]](https://bugs.ruby-lang.org/issues/19783)


## Other notable changes since 3.2

### IRB

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

- Advanced `irb:rdbg` integration that provides an equivalent
debugging experience to `pry-byebug`
([doc](https://github.com/ruby/irb#debugging-with-irb)).
- Pager support for `ls`, `show_source` and `show_cmds` commands.
- More accurate and helpful information provided by the `ls` and
`show_source` commands.
- Experimental autocompletion using type analysis
([doc](https://github.com/ruby/irb#type-based-completion)).
- It is now possible to change the font color and font style in the
completion dialog by a newly introduced class Reline::Face
([doc](https://github.com/ruby/ruby/blob/master/doc/reline/face.md))

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.

* `it` calls without arguments in a block with no ordinary parameters are
  deprecated. `it` will be a reference to the first block parameter in Ruby 3.4.
  [[Feature #18980]](https://bugs.ruby-lang.org/issues/18980)

### Removed environment variables

The following deprecated methods are removed.

* Environment variable `RUBY_GC_HEAP_INIT_SLOTS` has been deprecated
and is a no-op. Please use environment variables
`RUBY_GC_HEAP_{0,1,2,3,4}_INIT_SLOTS` instead. [[Feature
#19785]](https://bugs.ruby-lang.org/issues/19785)

## 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 rubygems.org
with `gem install readline-ext`.
* We no longer need to install libraries like `libreadline` or `libedit`.

## Standard library updates

RubyGems and Bundler warn if users do `require` the following gems
without adding them to Gemfile or gemspec. This is because they will
become the bundled gems in the future version of Ruby.

This warning is suppressed if you use bootsnap gem. We recoomend to
run your application with `DISABLE_BOOTSNAP=1` environmental variable
at least once. This is limitation of this version.

Targeted libraries are:
  * abbrev
  * base64
  * bigdecimal
  * csv
  * drb
  * getoptlong
  * mutex_m
  * nkf
  * observer
  * racc
  * resolv-replace
  * rinda
  * syslog

The following default gem is added.

* prism 0.19.0

The following default gems are updated.

* RubyGems 3.5.3
* abbrev 0.1.2
* base64 0.2.0
* benchmark 0.3.0
* bigdecimal 3.1.5
* bundler 2.5.3
* cgi 0.4.1
* csv 3.2.8
* date 3.3.4
* delegate 0.3.1
* drb 2.2.0
* english 0.8.0
* erb 4.0.3
* error_highlight 0.6.0
* etc 1.4.3
* fcntl 1.1.0
* fiddle 1.1.2
* fileutils 1.7.2
* find 0.2.0
* getoptlong 0.2.1
* io-console 0.7.1
* io-nonblock 0.3.0
* io-wait 0.3.1
* ipaddr 1.2.6
* irb 1.11.0
* json 2.7.1
* logger 1.6.0
* mutex_m 0.2.0
* net-http 0.4.0
* net-protocol 0.2.2
* nkf 0.1.3
* observer 0.1.2
* open-uri 0.4.1
* open3 0.2.1
* openssl 3.2.0
* optparse 0.4.0
* ostruct 0.6.0
* pathname 0.3.0
* pp 0.5.0
* prettyprint 0.2.0
* pstore 0.1.3
* psych 5.1.2
* rdoc 6.6.2
* readline 0.0.4
* reline 0.4.1
* resolv 0.3.0
* rinda 0.2.0
* securerandom 0.3.1
* set 1.1.0
* shellwords 0.2.0
* singleton 0.2.0
* stringio 3.1.0
* strscan 3.0.7
* syntax_suggest 2.0.0
* syslog 0.1.2
* tempfile 0.2.1
* time 0.3.0
* timeout 0.4.1
* tmpdir 0.2.0
* tsort 0.2.0
* un 0.3.0
* uri 0.13.0
* weakref 0.1.3
* win32ole 1.8.10
* yaml 0.3.0
* zlib 3.1.0

The following bundled gem is promoted from default gems.

* racc 1.7.3

The following bundled gems are updated.

* minitest 5.20.0
* rake 13.1.0
* test-unit 3.6.1
* rexml 3.2.6
* rss 0.3.0
* net-ftp 0.3.3
* net-imap 0.4.9
* net-smtp 0.4.0
* rbs 3.4.0
* typeprof 0.21.9
* debug 1.9.1

See GitHub releases like [Logger](https://github.com/ruby/logger/releases) or
changelog for details of the default gems or bundled gems.

See [NEWS](https://github.com/ruby/ruby/blob/v3_3_0/NEWS.md)
or [commit logs](https://github.com/ruby/ruby/compare/v3_2_0...v3_3_0)
for more details.

With those changes, [5532 files changed, 326851 insertions(+), 185793
deletions(-)](https://github.com/ruby/ruby/compare/v3_2_0...v3_3_0#file_bucket)
since Ruby 3.2.0!

Merry Christmas, Happy Holidays, and enjoy programming with Ruby 3.3!

## Download

* <https://cache.ruby-lang.org/pub/ruby/3.3/ruby-3.3.0.tar.gz>

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      SHA1: 1a7e56851bf29bda1183aca99b3b323c58e0187b
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* <https://cache.ruby-lang.org/pub/ruby/3.3/ruby-3.3.0.tar.xz>

      SIZE: 16345456
      SHA1: c8f68e1b0a114b90460a0b44165a3b2f540fa5b6
      SHA256: 676b65a36e637e90f982b57b059189b3276b9045034dcd186a7e9078847b975b
      SHA512: 7959c5753bfa0bfc4d6d74060869aabbe9815c1c97930659da11b917ee0803ddbbd80e869e00c48b8694b4ba48709c3b6493fd045568e36e902616c35ababf01

* <https://cache.ruby-lang.org/pub/ruby/3.3/ruby-3.3.0.zip>

      SIZE: 26935108
      SHA1: a433eef1d7f96daeaf3b4cb842d0ed2dd82e7dc1
      SHA256: 0e6563f679dd3694732eb3addf9de681c67b584602ac574376b60e7a509d2cd8
      SHA512: a94a85937a14b217c1f4b90d24185289ed4aee79239c4f3eecf8034d3fd34e65ee8d66869473857ed153067188adc9b70c0471e4ebe842c9f98ef60c34090450

## 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.
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