The JRuby community is pleased to announce the release of JRuby 9.4.9.0.

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

JRuby 9.4.x targets Ruby 3.1 compatibility.

Thank you to our contributors this release, you help keep JRuby moving forward! @kares, @jpcamara, @jsvd

Ruby Compatibility

• Various fixes for keyword arguments. #8344, #8344, #8382, #8389
• Mutex has been fixed to check for thread interrupts (Thread#kill, Thread#raise) immediately after acquiring the lock. #8403, #8404

Standard Library

• The fiddle library is now a default gem and can be upgraded independently of JRuby. #8385

Developer Experience

• The core jar file of JRuby can be rebuilt more quickly by calling Maven with the -Dcore flag. #8326
• Support for Coordinated Restore at Checkpoint (OpenJDK Project CRaC), which allows snapshotting a running JRuby process and quickly resuming it later. #8367

Java Integration

• The "lazy" constants feature for classes imported from Java, introduced in JRuby 9.4.8.0, has been reverted due to spurious warnings. We'll revisit it in a future release. #8349, #8368, #8399, #8400, #8401
• Functions were added to allow flushing out thread-local and fiber-local storage for an entire JRuby runtime. #8369

Security

• REXML was updated to 3.3.9 to get recent fixes and to address CVE-2024-49761, a ReDOS vulnerability. Only users parsing unsanitized XML with REXML are affected. #8396