NEWS for Ruby 3.3.0¶ ↑

This document is a list of user-visible feature changes since the 3.2.0 release, except for bug fixes.

Note that each entry is kept to a minimum, see links for details.

Language changes¶ ↑

Command line options¶ ↑

• A new performance warning category was introduced. They are not displayed by default even in verbose mode. Turn them on with -W:performance or Warning[:performance] = true. [Feature #19538]

• The RUBY_GC_HEAP_INIT_SLOTS environment variable has been deprecated and removed. Environment variables RUBY_GC_HEAP_%d_INIT_SLOTS should be used instead. [Feature #19785]

Core classes updates¶ ↑

Note: We’re only listing outstanding class updates.

• Array

  • Array#pack now raises ArgumentError for unknown directives. [Bug #19150]

• Dir

  • Dir.for_fd added for returning a Dir object for the directory specified by the provided directory file descriptor. [Feature #19347]

  • Dir.fchdir added for changing the directory to the directory specified by the provided directory file descriptor. [Feature #19347]

  • Dir#chdir added for changing the directory to the directory specified by the provided Dir object. [Feature #19347]

• MatchData

  • MatchData#named_captures now accepts optional symbolize_names keyword. [Feature #19591]

• Module

  • Module#set_temporary_name added for setting a temporary name for a module. [Feature #19521]

• ObjectSpace::WeakKeyMap

  • New core class to build collections with weak references. The class use equality semantic to lookup keys like a regular hash, but it doesn't hold strong references on the keys. [Feature #18498]

• Proc

  • Now Proc#dup and Proc#clone call #initialize_dup and #initialize_clone hooks respectively. [Feature #19362]

• Process.warmup

  • Notify the Ruby virtual machine that the boot sequence is finished, and that now is a good time to optimize the application. This is useful for long running applications. The actual optimizations performed are entirely implementation specific and may change in the future without notice. [Feature #18885]

• Process::Status

  • Process::Status#& and Process::Status#>> are deprecated. [Bug #19868]

• Range

  • Range#reverse_each can now process beginless ranges with an Integer endpoint. [Feature #18515]

• Refinement

  • Add Refinement#target as an alternative of Refinement#refined_class. Refinement#refined_class is deprecated and will be removed in Ruby 3.4. [Feature #19714]

• String

  • String#unpack now raises ArgumentError for unknown directives. [Bug #19150]

  • String#bytesplice now accepts new arguments index/length or range of the source string to be copied. [Feature #19314]

• TracePoint

  • TracePoint supports rescue event. When the raised exception was rescued, the TracePoint will fire the hook. rescue event only supports Ruby-level rescue. [Feature #19572]

Stdlib updates¶ ↑

• RubyGems and Bundler warn if users require gem that is scheduled to become the bundled gems in the future version of Ruby. [Feature #19351] [Feature #19776] [Feature #19843]

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

• Socket#recv and Socket#recv_nonblock returns nil instead of an empty string on closed connections. Socket#recvmsg and Socket#recvmsg_nonblock returns nil instead of an empty packet on closed connections. [Bug #19012]

• Random::Formatter#alphanumeric is extended to accept optional chars keyword argument. [Feature #18183]

The following default gem is added.

• prism 0.17.1

The following default gems are updated.

• RubyGems 3.5.0.dev

• base64 0.2.0

• benchmark 0.3.0

• bigdecimal 3.1.5

• bundler 2.5.0.dev

• cgi 0.4.0

• csv 3.2.8

• date 3.3.4

• delegate 0.3.1

• drb 2.2.0

• english 0.8.0

• erb 4.0.3

• etc 1.4.3.dev.1

• fcntl 1.1.0

• fiddle 1.1.2

• fileutils 1.7.2

• find 0.2.0

• getoptlong 0.2.1

• io-console 0.6.1.dev.1

• irb 1.9.0

• 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 0.4.0

• open3 0.2.0

• 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 5.1.1.1

• rdoc 6.6.0

• reline 0.4.0

• rinda 0.2.0

• securerandom 0.3.0

• shellwords 0.2.0

• singleton 0.2.0

• stringio 3.1.0

• strscan 3.0.8

• syntax_suggest 1.1.0

• tempfile 0.2.0

• 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-imap 0.4.4

• net-smtp 0.4.0

• rbs 3.2.2

• typeprof 0.21.8

• debug 1.8.0

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

Supported platforms¶ ↑

Compatibility issues¶ ↑

Stdlib compatibility issues¶ ↑

• racc is promoted to bundled gems.

• You need to add racc to your Gemfile if you use racc under bundler environment.

• 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.

C API updates¶ ↑

Implementation improvements¶ ↑

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

• Name resolution such as Socket.getaddrinfo can now be interrupted. [Feature #19965]

YJIT¶ ↑

• 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!

• Significantly improved memory usage over 3.2

  • Metadata for compiled code uses a lot less memory.

  • Generate more compact code on ARM64

• Compilation speed is now slightly faster than 3.2.

• Add RubyVM::YJIT.enable that can enable YJIT later

• You can start YJIT without modifying command-line arguments or environment variables.

• 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.

• Code GC now disabled by default, with --yjit-exec-mem-size treated as a hard limit

• Can produce better copy-on-write behavior on forking web servers such as unicorn

• Use the --yjit-code-gc option to automatically run code GC when YJIT reaches the size limit

• 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.

• Exit tracing option now supports sampling

• --trace-exits-sample-rate=N

• More thorough testing and multiple bug fixes

• --yjit-stats=quiet is added to avoid printing stats on exit.

• --yjit-perf is added to facilitate profiling with Linux perf.

MJIT¶ ↑

• MJIT is removed.

• --disable-jit-support is removed. Consider using --disable-yjit --disable-rjit instead.

RJIT¶ ↑

• Introduced a pure-Ruby JIT compiler RJIT.

• 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.

M:N Therad scheduler¶ ↑

• M:N Thread scheduler is introduced. [Feature #19842]

• Background: Ruby 1.8 and before, M:1 thread scheduler (M Ruby threads with 1 native thread. Called as User level threads or Green threads) is used. Ruby 1.9 and later, 1:1 thread scheduler (1 Ruby thread with 1 native thread). M:1 threads takes lower resources compare with 1:1 threads because it needs only 1 native threads. However it is difficult to support context switching for all of blocking operation so 1:1 threads are employed from Ruby 1.9. M:N thread scheduler uses N native threads for M Ruby threads (N is small number in general). It doesn’t need same number of native threads as Ruby threads (similar to the M:1 thread scheduler). Also our M:N threads supports blocking operations well same as 1:1 threads. See the ticket for more details. Our M:N thread scheduler refers on the gorotuine scheduler in the Go language.

• In a ractor, only 1 thread can run in a same time because of implementation. Therefore, applications that use only one Ractor (most applications) M:N thread scheduler works as M:1 thread scheduler with further extension from Ruby 1.8.

• M:N thread scheduler can introduce incompatibility for C-extensions, so it is disabled by default on the main Ractors. RUBY_MN_THREADS=1 environment variable will enable it. On non-main Ractors, M:N thread scheduler is enabled (and can not disable it now).

• N (the number of native threads) can be specified with RUBY_MAX_CPU environment variable. The default is 8. Note that more than N native threads are used to support many kind of blocking operations.