JRuby

The JRuby community is pleased to announce the release of JRuby 10.0.8.0.

• Homepage: https://www.jruby.org/
• Download: https://www.jruby.org/download

JRuby 10.0.x targets Ruby 3.4 compatibility.

Thank you to our contributors this release, you help keep JRuby moving forward! This cycle we had several new contributors and hundreds of pull requests. Keep it coming, JRubyists! @aminmansuri, @kares, @hiukkanen, @evaniainbrooks, @stefanlew-tractive, @sampokuokkanen, @zev, @matrei, @notsrch, @sferik, @RaphaelFakhri

Notable Changes

Security

• The asm bytecode library was updated to 9.11.1 to fix recent CVEs (none of which affect JRuby). #9858

Standard Library

• The standard library is updated to match or exceed Ruby 3.4.12. #9747, #10008
• jruby-openssl is updated to 0.16.3. #9726
• io-console is updated to 0.9.5. #9923
• pstore is updated to 0.2.1. #10008
• syntax_suggest is updated to 2.0.3. #10008
• uri is updated to 1.0.4, addressing CVE-2025-61594. #10008
• net-imap is updated to 0.5.15, addressing several CVEs. #10008

Java Integration

• Java 27 is now officially supported. #9787
• Several fixes to reduce GC roots keeping the JRuby runtime or classloader from being collected after teardown. #9781, jnr/jffi#200, jnr/jffi#201, #9894, #9927, #9895, #9922, [#9928]

Performance

• Reduced maximum JIT-compilable method size to 500 instructions from 3000. #9913

54 Issues and PRs resolved for 10.0.8.0

• #9328 Spurious Struct#initialize keyword argument warning re-occurring
• #9510 Signal.trap with numeric USR1 value traps SIGBUS on Linux

• #9524 [Array#-, #&, #

  call #hash on elements where MRI does not]#9524

• #9651 JRuby 10.0/CRuby 3.4+ compat: assignment to an outer local variable named it inside a block seems to assume/create a block level shadow
• #9681 JRuby mistakes != for a setter
• #9722 IO#close raises Errno::EBADF after Thread#kill closed the channel underneath it
• #9723 Do not report a channel closed underneath us as EBADF on close
• #9726 [deps] bump jruby-openssl to 0.16.3
• #9729 Allow endless definition of comparison operators (Fixes #9681)
• #9731 Fixes #9651. Write to outer it variable from inside blocks
• #9735 Fix Ripper endless method definitions rejecting operator methods ending in =
• #9737 Method defined on a class stays invisible to indy call sites while another thread runs a module’s bulk invalidation
• #9738 Keep SwitchPoints live until bulk invalidation has run
• #9739 Disallow unknown keywords
• #9747 Update 10.0 to latest 3.4 stdlib and tests
• #9755 Concurrent reads of a frozen two-item array can permanently replace its elements with nil
• #9756 align small array behavior with MRI
• #9757 Atomically transition to unpacked
• #9764 Wait for another thread’s require of an autoload’s file
• #9777 With invokedynamic, class_attribute writes can leak into the superclass after define_method on the subclass’s singleton class
• #9781 A runtime in a disposable class loader can’t be garbage collected after tearDown
• #9783 Pass keyword arguments to IO.foreach, IO#each and IO#each_line enumerators
• #9784 Accept separator, limit and keywords in ARGF line methods
• #9785 Fix ClassCastException in ARGF.gets and readline when $stdin is not an IO
• #9787 Support JDK 27
• #9808 Route Kernel#readline through ARGF.readline
• #9809 Use MonomorphicCallSite for ARGF forwarding sites
• #9835 Replace deprecated calls where context is already in scope
• #9858 Update asm to get recent security fixes
• #9863 Mark overrides of deprecated methods as @Deprecated
• #9889 Update Joni for expansion limits
• #9894 Don’t cache LibrarySearcher’s index wrappers in thread-locals
• #9895 Store MethodGatherer’s filtered methods as JDK types
• #9898 Update joni for invalid unicode fix
• #9902 Update io-console for isatty alias fix
• #9903 Update JNR for jffi cleaner fix
• #9913 Reduce default max JIT size to 500
• #9922 Remove StableClassValue values from their classes when cleared
• #9923 Update io-console to 0.9.5
• #9925 Update Java Native Runtime
• #9927 Hold the fstring dedup wrapper weakly in its thread-local
• #9944 Avoid calling a Regexp match during signal handling
• #9945 Test the nested jar temp dir cleanup
• #9951 Keep PosixShim’s errno as an ordinal
• #9965 Use String.getBytes and new String for UTF-8 conversion of Java strings
• #9969 Keep a deduplicated string’s table entry while the string lives
• #9972 Mutex#synchronize can still exit with the lock held after Thread#raise / Timeout (contended path, follow-up to #8585)
• #9980 Release mutex for any throwable
• #9984 Don’t wake selectors after they go back to the pool
• #9991 Decode raw bytes without a thread-local buffer
• #9996 Use the platform’s signal numbers in Signal.trap
• #10002 Backport #9470 to 10.0.x (Hash duplicated through (…) forwarding in JIT-compiled methods)
• #10003 Backport small kwargs fixes
• #10008 [10.0] Update standard library to Ruby 3.4.12