[fizx]

Our production thrift code generator (now at https://github.com/twitter/scrooge) was JRuby for about a year, before Robey decided it was an abomination and rewrote it in scala.

JRuby was easy because you can Maven require it from a Java project. Ruby already has a Thrift IDL parser, so I just stole the AST from that, and used an ERb template to write out corresponding scala. The whole thing was maybe 200LOC.

But yeah, that's the only JRuby that ever did anything production related at Twitter.