The jnr-constants fix and subsequent commits addressed TORQUE-982 but were never incorporated into a JRuby release. The workaround in Torquebox masked this fact, but other users have reported the same issue (@MarkMenard today).
We need to roll jnr-constants 0.8.5 release out and include it in JRuby 1.7.5.
Note that users can work around this issue the same way as Torquebox by running the following code at least once in the classloader that loads their app instances: torquebox/torquebox@dee925f
For the record, this manifests as a NullPointerException when loading some core libraries that hit jnr-constants ConstantSets in parallel. @MarkMenard's case was that the fcntl library failed to load with error message "library `fcntl' could not be loaded".
Here's the workaround I'm using care of bbrowning. https://gist.github.com/MarkMenard/5710668
Cool, thanks @MarkMenard and @bbrowning!
@MarkMenard would be great to mention it in JRuby-Rack's wiki ... https://github.com/jruby/jruby-rack/wiki thanks
jnr-constants was updated.