Re: [Boost-users] Regex lib and thread safety

... since I've built-in the mutexes I don't have this problem at all anymore; however, if I see this problem again and it's reproducable, I'll cut it down to a test case and put up the source code.

Sounds like it may be race condition related again: if one thread tries to use a regex that is actually in the process of being constructed by another thread, then it's sub-expression count may suddenly change, leading to your assertion. Just guessing at this point, though... John.