To bring in yet someone else to this discussion, Mark Hammond and I were chatting with Brendan Eich (of JavaScript and Mozilla fame) last week about interpreter locks and the like, and Brendan mentioned that he had done a lot of possibly reusable work in optimizing the various kinds of thread lock strategies in JavaScript, as JS is used a lot server-side. Specifically he was talking about some 'multi-level' locking stuff which sounded impressive to me at least. I doubt if Brendan has time to dig into either of Perl or Python's internals, but I'm sure he'll provide general pointers if folks ask nicely. =) Brendan, do you care to give an executive overview of the locking strategies used in JS? --david ascher PS: Brendan: If you want to know the context of this discussion, see: http://aspn.activestate.com/ASPN/Mail/Browse/Threaded/python-dev