JRuby.org News

JRuby 10.1.0.0 Released

2026-04-21T00:00:00+00:00

The JRuby community is pleased to announce the release of JRuby 10.1.0.0.

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

JRuby 10.1.0.x targets Ruby 4.0 compatibility.

Thank you to our contributors this release, you help keep JRuby moving forward!

JRuby 10.1: Experimenting and Evolving

JRuby 10.1.0.0 is our first major release since catching up with Ruby compatibility. We have used this opportunity to explore many experimental optimizations and improvements we have been chasing for many years. Ruby 4.0 compatibility is largely complete, but there will be additional features added in update releases. We also plan to continue with large scale experiments in subsequent updates, and recommend production users continue to use JRuby 10.0 while we work toward stabilization of the 10.1 series.

Here’s an overview of the major enhancments already in JRuby 10.1.0.0 and others planned for update releases in the coming months.

Reduced Object Size

In JRuby 10.1 all objects have been reduced in size by 8 bytes, bringing the base object size down from 32 bytes to 24 bytes. This translates into smaller objects across the system, reduced GC load, higher allocation throughput, and better cache locality.

On JVM versions that support Compact Object Headers (JEP 450: “Project Lilliput”) the base object size can be further reduced to 16 bytes, 40% smaller than objects in the standard Ruby implememtation.

Evolving Strings, Arrays, and Hashes

During the upcoming JRuby 10.1 update releases, we plan to introduce new versions of String, Array, and Hash that are optimized for memory compactness, concurrency, or integration with other JVM languages. To support these features, we have made the internal implementations RubyArray and RubyHash into abstract classes and deprecated the direct constructors for RubyString. Please test your JRuby extension code and make sure it does not call abstract or deprecated constructors.

Smaller Numeric Representations

JRuby’s internal class for representing 64-bit signed Integer values, RubyFixnum, has been split into two versions: LongFixnum and ShortFixnum. Combined with the reduced size of objects overall, this reduces the size of these long and short-ranged Integer objects from 40 bytes to 32 bytes or 24 bytes (24 bytes or 16 bytes if using Compact Object Headers). The size of Float objects have similarly been reduced from 40 bytes to 32 bytes. These size reductions help improve the performance of numeric algorithms and reduce impact to the heap and GC of boxing numeric values.

Cross-platform Prism Parser

JRuby 10.1 ships with support for the Prism Ruby parser, packaged as a set of pre-optimized native builds (for Windows, Linux, and MacOS on x86_64 or arm64) or as a WASM build on other platforms. We’re still working out a few remaining features, but we encourage experimenters to enable it by passing -Xparser.prism to JRuby. We plan to make this the default parser once the remaining issues are solved.

Direct Argument Passing

We have also laid the groundwork to start passing all forms of method arguments on the call stack, avoiding boxed collections for most optional and keyword arguments. In upcoming JRuby 10.1 releases, we will begin to connect these call paths up for both pure-Ruby and native (Java) method targets, eliminating box allocation and drastically improving the peformance of such forms. Watch this space for rapid improvements.

New Policy for EOL and LTS Releases

With the release of JRuby 10.1, we are moving JRuby 9.4 into a “soft” EOL status. This means we will no longer be doing regular OSS release updates of JRuby 9.4, but users may get in contact with us to sponsor continued support. JRuby 10.0 will be our stable LTS release until April 2028 and we recommend all users upgrade or get in contact with us for assistance. JRuby 10.1 will be our “tip” release line, with many exciting optimizations and enhancements due to land over the next several months.

Going forward, we will provide a new LTS baseline release every two years, starting in spring of 2027, and alternating years will be considered as edge or development versions without LTS guarantees. This will allow us a free hand to keep bringing you more experimental features while still providing a stable baseline for more conservative users.

Try JRuby Today!

Users can install JRuby 10.1 through the usual means, and we encourage you to give it a try and let us know how it handles your applications and libraries. We have much more planned for the 10.1 updates and hope to move fast and push the edges of what’s possible with Ruby on the JVM.

59 Issues and PRs resolved for 10.1.0.0

#8716 dup a lot
#8747 Launcher script chokes on GraalVM release file
#9055 Array experiments
#9066 Move Set to a core class [Ruby 4.0]
#9069 Implement Ruby 4.0 support
#9074 Avoid array allocation for *nil, by not calling nil.to_a
#9075 Selective inspect of instance variables
#9077 No numbered parameters in Binding#local_variables
#9078 Add Math.{expm1,log1p}
#9079 Align IO.select timeout logic with CRuby
#9083 Implement missing raise features
#9085 Specialize Fixnum
#9090 Reduce the size of the varTableStamp
#9091 Shrink varTableStamp
#9095 Eliminate global flags
#9096 Cache object ID and hash in low-count immediate values
#9102 Add a fast path for hashing numerics and immediates
#9113 Performance regression in RubyHash for large hashes (~8-10x slower than JRuby 1.7)
#9119 Implement fast-path builtin method flags
#9123 Fast builtin validation experiment
#9124 Reduce load factor for Hash from 5 to 2
#9136 Marshal.load 2.9x regression vs JRuby 1.7
#9143 Cache both hash forms for FString
#9148 Allow logical ops to begin on beginning of next line
#9154 Mask internal Ruby backtrace elements like native masking
#9156 Small marshal fixes
#9174 Add complete thread-local builtin tracking system (Issues #9116, #9119)
#9180 Implement implicit param logic for Binding
#9181 Fix Data subclasses with ivars
#9202 A Data object should be frozen even if it has no members
#9209 Add ruby_bug for spec of Data with no members being frozen
#9210 Remove Process::Status#& and Process::Status#»
#9233 Load boot scripts from classloader URI
#9235 Use capitalized Class and Module for frozen errors
#9236 [Properly handle keywords in {Kernel Thread Fiber}#raise]#9236
#9238 Cloned class’s singleton class has too many classes in hierarchy
#9239 Fix for cloned class singleton class has too many ancestors
#9250 Update Unicode to Version 17.0.0 and Emoji Version 17.0
#9262 Abstract RubyHash
#9263 Implicit param fixes for proc and binding
#9266 Endless method with modifier method does not parse
#9273 Cleanup recursion guards
#9277 Use live counts for event hook stats
#9279 Move fiddle back to default temporarily for resolv
#9286 Proposing RISC-V architecture support
#9287 Add riscv64 platform support
#9298 Ensure we have a classloader to boot from
#9299 Delete methods deprecated prior to JRuby 9.4.0.0
#9300 Replace now-deprecated wait_timeout
#9313 Time being returned as ASCII-8BIT encoding in JRuby 10
#9318 Process.detach raises ArrayIndexOutOfBoundsException if called from a thread that is not the main thread
#9325 [fix] NullPointerException from closed IO
#9362 Allow endless methods to be an argument to methods like visibity
#9365 Marshal load perf
#9371 Deprecate all public RubyString constructors
#9374 Integrate WASM-based Prism parser into standard build
#9383 Disable IntFixnum
#9384 Set.new(a_set) throws LocalJumpError
#9385 Fixes #9384. Set.new(a_set) throws LocalJumpError

JRuby 10.0.5.0 Released

2026-04-06T00:00:00+00:00

The JRuby community is pleased to announce the release of JRuby 10.0.5.0.

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

JRuby 10.0.5.x targets Ruby 3.4 compatibility.

Thank you to our contributors this release, you help keep JRuby moving forward! @evaniainbrooks, @kares, @chadlwilson, #jimtng

Compatibility

Fixed: Two bugs in the JIT compiler that broke certain super calls and defined_method yields. (#8944, #8946, #9310, #9349)
Fixed: Fiber#raise left the fiber in an resumable state by not correctly transfering control. (#9297, #9356)
Fixed: Connecting a socket using nonblocking operations failed to complete the establishment of the connection. This affected Redis users, among other cases. (#9304, #9305)
Fixed: Process#detach raised a NullPointerException if called from a non-main thread. (#9314, #9311)

JVM Integration

Java 26 is officially supported. (#9332)

Platform Integration

New platform support: The native library backend for JRuby, JNR, has been updated to include support for the RISCv64 architecture.
Fixed on Windows: File#flock used unsupported native operations on Windows, causing it to raise errors. This affected the “logger” library, among other cases. (#9347, #9348)
Fixed on Windows: IO#popen failed to pass keyword arguments if also given a leading environment hash. (#9351, #9352)

Stability

Fixed: Several memory leaks that affected users running multiple JRuby instances in a single process. (#9070, #9092, #9187, #9359)

43 Issues and PRs resolved for 10.0.5.0

JRuby 10.0.4.0 Released

2026-03-04T00:00:00+00:00

The JRuby community is pleased to announce the release of JRuby 10.0.4.0.

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

JRuby 10.0.4.x targets Ruby 3.4 compatibility.

Thank you to our contributors this release, you help keep JRuby moving forward! @evaniainbrooks, @katafrakt, @mrnoname1000

Standard Library

The syslog library moves to bundled gems. (#9198)
The unicode_normalize library is now thread-safely loaded as an internal library (#9231, #9232)

43 Issues and PRs resolved for 10.0.4.0

JRuby 10.0.3.0 Released

2026-02-02T00:00:00+00:00

The JRuby community is pleased to announce the release of JRuby 10.0.3.0.

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

JRuby 10.0.3.x targets Ruby 3.4 compatibility.

Thank you to our contributors this release, you help keep JRuby moving forward! @mrnoname1000, @ngr-ilmarh, @Earlopain, @philr, @jotamartos, @kares, @aleksandrs-ledovskis, @trinistr, @katafrakt, @chadlwilson, @khasinski, @evaniainbrooks

Compatibility

JRuby now reports RbConfig::CONFIG['arch'] without a version number, as universal-java. This allows using different JDK versions without triggering RubyGems missing extension warnings for installed gems. The host Java version is still available as RbConfig::CONFIG['arch_version']. #9107

Standard Library

The non-gem standard library is upgraded to Ruby 3.4.5 #8967
rexml is updated to 3.4.4 to address CVE-2025-58767. #9011
syslog is moved to a default gem at version 0.4.0. The syslog gem now includes JRuby support. #9109, ruby/syslog#1
strscan is updated to 3.1.7. #9159

Documentation

Ruby ri documentation for core and standard library are now included in the release distribution. #9049, #9052

All Issues/PRs

JRuby 9.4.14.0 Released

2025-08-28T00:00:00+00:00

The JRuby community is pleased to announce the release of JRuby 9.4.14.0.

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

JRuby 9.4.14.x targets Ruby 3.1 compatibility.

Thank you to our contributors this release, you help keep JRuby moving forward! @matthias-fratz-bsz, @ikaronen-relex, @ylecuyer

Compatibility

Ruby version is now 3.1.7. (#8966)

Libraries

strscan is updated to 3.1.5. (#8897)
cgi is updated to 0.3.7 to resolve CVE-2025-27220 and CVE-2025-27219 (#8954, #8966)
uri is updated to 0.12.4. (#8966)
net-smtp is updated to 0.3.1.1. (#8966)
rss is updated to 0.3.1. (#8966)
Non-gem stdlib has been updated to Ruby 3.1.7 sources. (#8966)

Build

jruby-maven-plugins is updated to 3.0.6 to resolve issues with garbled gem poms. (#8898)
The stdlib build scripts have been modified to work with latest polyglot-ruby. (#8634, #8963)

Usability

bin/ruby and bin/ruby.bat are now shipped in the distribution, to make installation simpler. (#8875)

29 Issues and PRs resolved for 9.4.14.0

JRuby 10.0.2.0 Released

2025-08-07T00:00:00+00:00

The JRuby community is pleased to announce the release of JRuby 10.0.2.0.

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

JRuby 10.0.2.x targets Ruby 3.4 compatibility.

Thank you to our contributors this release, you help keep JRuby moving forward!

7 Issues and PRs resolved for 10.0.2.0

JRuby 10.0.1.0 Released

2025-07-17T00:00:00+00:00

The JRuby community is pleased to announce the release of JRuby 10.0.1.0.

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

JRuby 10.0.1.x targets Ruby 3.4 compatibility.

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

Compatibility

Zeitwerk is now fully supported. (#6781, #8852, #8853, #8863, #8777)

Libraries

The net-imap library is updated from 0.5.4 to 0.5.8 (#8826, #8828)

62 Issues and PRs resolved for 10.0.1.0

JRuby 9.4.13.0 Released

2025-06-10T00:00:00+00:00

The JRuby community is pleased to announce the release of JRuby 9.4.13.0.

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

JRuby 9.4.13.x targets Ruby 3.1 compatibility.

Thank you to our contributors this release, you help keep JRuby moving forward!

Stability

Fixed a slow memory leak in subclass management. (#8842, #8844)
Fixed a potential deadlock during multi-threaded boot and concurrent JIT compilation. (#8845, #8849)

Usability

Backported JRuby .sh launcher features from JRuby 10, including AppCDS flags for improved startup time. (#8565, #8625, #8626, #8652, #8653, #8656, #8754)

56 Issues and PRs resolved for 9.4.13.0

#8351 Zlib::GzipReader missing each_char iterator
#8426 Dir[] vs “../../”
#8506 Test new version of resolv
#8526 obj.first caused Java::JavaUtil::NoSuchElementException on an empty Java21 ArrayList
#8542 Fix Dir.glob ../ and cases
#8565 JRuby native launcher seems to get confused when both –dev and -Xcompile.mode=JIT are applied
#8574 Improvements to support json library
#8577 ArgumentError: unknown keyword for required keyword argument
#8599 Fixes #8577. kwargs checking: Use bits instead of index
#8608 add zlib each_char
#8611 Setting an instance var on a Java object no longer warns
#8613 Warn when creating a new ivar table on JavaProxy wrapper
#8623 Installing sassc broke on jruby-head on Windows
#8625 Add –cache flag to regenerate AppCDS
#8626 Fix default arguments for generating AppCDS flag
#8635 Fix tr! and reverse! on ByteList view with non-zero begin index
#8643 Fixes to get stringio tests and specs green
#8645 Update stringio to 3.1.5
#8648 Handle errors whe looking for Java executable
#8652 Use set -u to avoid accessing uninitialized variables
#8653 Align 9.4 launcher with 10
#8654 fix glob dir on windows
#8655 Make some private helpers for glob
#8656 Additional fixes for jruby.sh
#8661 Update Unicode to 15.0
#8663 copy-rename-maven-plugin version
#8667 Update jcodings to 1.0.62 and joni to 2.2.4
#8671 fix a regression in KDDI transcoding
#8681 Update MRI core tests and tag failures
#8686 rbByteEncode fails to no-op when encodings are the same
#8687 Handle encoding checks as in strTranscode
#8688 Tracing :call with TracePoint (and –debug flag) makes kwargs unusable
#8691 Implement AutoCloseable on JRubyEngine
#8692 Save original callers callInfo in tracepoint
#8696 New restriction warnings on Java 24
#8715 Fix missing 2 arg for IO#readline
#8728 Incorrect warning: given block not used
#8731 [ji] avoid false duplicate method warning
#8733 Remove this warning to match standard set.rb
#8754 Backport jruby.sh from JRuby 10
#8755 Update uri to version 0.12.3 in JRuby 9.4
#8789 Dir.glob and Dir[] on existing file URL raises error
#8795 Possible typo in lib/ruby/stdlib/jruby/compiler.rb:61
#8805 Possible NPE in RubyModule:searchWithCacheMiss() found by SAST
#8806 Possible NPE in StringSupport:rbStrEnumerateLines() found by SAST
#8820 Fix recent potential NPE reports
#8821 Always cache undef along these paths
#8825 Update net-imap from 0.2.3 to 0.2.5
#8827 Update to net-imap 0.2.5 for security fixes
#8830 Splat with multi-line expression improperly expands
#8834 Missing splatNode creation
#8842 Metaspace leak in 9.4
#8844 Use a normal ClassValue for all such cases
#8845 Fix locking of stable class values for JI proxies
#8849 Clean up some locking around hierarchy modification
#8857 Migrate to the new Maven Central publishing system

JRuby 9.4.12.1 Released

2025-05-07T00:00:00+00:00

The JRuby community is pleased to announce the release of JRuby 9.4.12.1.

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

JRuby 9.4.12.x targets Ruby 3.1 compatibility.

Security

jruby-openssl has been updated to 0.15.4, which re-enables hostname verification by default. This addresses CVE-2025-46551 and GHSA-72qj-48g4-5xgx.

JRuby 10.0.0.1 Released

2025-05-07T00:00:00+00:00

The JRuby community is pleased to announce the release of JRuby 10.0.0.1.

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

We’ve jumped to Ruby 3.4 compatibility and Java 21 minimum to bring you the best Ruby on JVM experience possible. We are confident this is the most compatible and stable major release we’ve ever had.

Security

jruby-openssl has been updated to 0.15.4, which re-enables hostname verification by default. This addresses CVE-2025-46551 and GHSA-72qj-48g4-5xgx.