Hello *, I face some issue with sporadic crashes in xpressive which I think a result of a race condition. The use case is: a function which needs to parse smth create local regex objects: const sregex any_char = _; sregex const& rdelim = parser_->delimiter(); //some dynamic delimiter token const sregex re_prefix = bos >> (s1=-*by_ref(any_char)) >> *(s2=by_ref(rdelim)) >> eos ; calling this function from multiple threads results in a crash with (boost 1.42, gcc 4.3.5 on debian linux). I previously had more crashes, but moved all regex objects to global space as const objects and they seem to be fine now. This is the only place I left with a local regex. In the stack trace it seems like internals of the local object regex are freed via boost weak_ptr with possible double delete attempt. The stack-trace of the created core-dump during the crash can be accessed via: https://docs.google.com/open?id=0BzJl1eEH-CCGODU5N2JhOTAtNWMxMy00OGNhLThhNzc... (Did not want to send addional 200k to the mailing list.) Many thanks for help, Ovanes