Thanks for the reply and submitted a bug report: FB16844222

Thanks for sharing this!

Actually think I figured it out - I was using some read and write queue accessor to arrays to prevent concurrency conflicts, and those seemingly caused thread locking when called too many times in a short period of time - please let me know if you see other insights though, and thanks for giving the hint of using the thread backtrace command!

@cyclic did you find a solution to catalyst?