Hi, I know that version 1 of John's logging library was never accepted and is probably not wildly used anymore nevertheless I found a nasty bug in it. It's strange but even after applying valgrind I found initially not the reason (probably I just assumed John's code is OK and it's something else) and it took some time until I resolved it. OK, for all users of this lib here is the patch: boost/log/detail/ts_posix.hpp: @@ -51,7 +51,7 @@ mutex & operator = ( const mutex & Not_Implemented); mutex( const mutex & From); public: - mutex() : m_mutex() { + mutex() : m_mutex(), m_count(0) { pthread_mutexattr_t attr; int res = pthread_mutexattr_init(&attr); assert(res == 0); I haven't checked whether this occurs in version 2 as well. Jens