JRuby 1.4 released
The developers of the Java implementation of the Ruby scripting language have now released version 1.4 of JRuby. The new version now supports Ruby 1.8.7 (patchlevel 174); the update was driven in part by the Ruby on Rails developers who are planning to make Ruby 1.8.7 the required minimum version of Ruby. The JRuby developers are also looking to the community for help testing JRuby's Ruby 1.9 support but do say "the bigger applications mostly just work at this point".
Other improvements in the new JRuby release are a new YAML (YAML Ain't Markup Language) parser, named Yecht, which should be "bug for bug" compatible with the Syck C based YAML parser, and a new embedding framework which should allow Java 6 developers to call the scripting language from their code "out of the box". JRuby 1.4.0 also comes with a Windows Installer and Windows Native Launcher, the latter replacing the previous, problematic batch scripts. A full list of new features and bug fixes is available in the release notes.
JRuby is a largely Ruby 1.8 compatible runtime environment for the Java Virtual Machine (JVM). From a deployment perspective, this is interesting, because it means Ruby programs can be run by JRuby anywhere a JVM is available. JRuby also benefits from the JVM's garbage collection and hotspot compiler; similar technologies exist for native Ruby, but the JVM implementations are quite mature and advanced. JRuby is also truly multi-threaded, thanks to the threading of the JVM. Several performance benchmarks have shown JRuby is currently the fastest Ruby 1.8 runtime.