Is anyone running JRuby in production for anything?
Every time I tried it out so far it turned out slower than MRI for me. Perhaps I was always hitting on pathological cases, though (tight data processing loops).
Don't have a citation for this, but I recall hearing that Square runs JRuby in production.
Separately, the start time makes JRuby awful for TDD/Dev, but once it has time to warm up in production it is vastly faster. Scan back through some Ruby Rogues episodes, they discuss it a few times in more detail.
