It seems that exceptions thrown by Ruby code are not propagated to the calling Ruby method when some Java code is involved in between.

Proof of concept: https://github.com/gmalkas/jruby-uncaught-exception-issue/blob/master/not_working.rb

Run the test:

  $ git clone git@github.com:gmalkas/jruby-uncaught-exception-issue.git && cd jruby-uncaught-exception-issue
  $ bundle && ./not_working.rb

The previous code should print Rescued StandardError twice but does not.

On the other hand, if the rescuing Ruby code is calling the failing code directly (without involving Java code), it works as expected: https://github.com/gmalkas/jruby-uncaught-exception-issue/blob/master/working.rb

Version information: jruby 1.7.16 (1.9.3p392) 2014-09-25 575b395 on Java HotSpot(TM) 64-Bit Server VM 1.8.0_25-b17 +jit [linux-amd64]

Let me know if you need any additional information.

Thank you!