Jython or JRuby?
The compatibility in either case is at the source-code level; with necessary changes where the Python or Ruby code invokes packages that involve native code (especially, standard Python packages like ctypes are not present in Jython).
It's a high level conceptual question. I have two separate code bases that serve the same purpose, one built in Python and the other in Ruby. I need to develop something that will run on JVM. So I have two choices: convert the Python code to Jython or convert the Ruby to JRuby. Since I don't know any of them, I was wondering if anyone can give me some guidance. Like which one runs faster, or more importantly which one has tools available for easy code migration(.pyc to .jar files)?