Hi Harry, On Sun, 20 Feb 2011, Harry Van Haaren wrote: In addition to the excellent suggestions from other folks... here's another approach. In Hydrogen/Composite, there is a central, critical audio lock.[3] For this lock, we set up a system for the central audio lock that would "log" the line of code that last locked the mutex. See [1] and [2]. Whenever you deadlock, you can look at this->d->__locker to see the file and line number where the mutex was last locked. This solution was suggested to us by Krzysztof Foltman, and once saved me a ton of time. Thanks, Krzysztof! The important parts are: /** * Convenience macro for locking the Engine. */ #ifndef RIGHT_HERE #define RIGHT_HERE __FILE__, __LINE__, __PRETTY_FUNCTION__ #endif And: class Engine : public EngineInterface { public: //... /////////////////////////////////////// // THE BIG LOCK /////////////////////////////////////// /* Mutex locking and unlocking * * Easy usage: Use the RIGHT_HERE macro like this... * engine->lock( RIGHT_HERE ); * * More complex usage: The parameters file and function * need to be pointers to null-terminated strings that are * persistent for the entire session. This does *not* * include the return value of std::string::c_str(), or * QString::toLocal8Bit().data(). * * Notes: The order of the parameters match GCC's * implementation of the assert() macros. */ void lock( const char* file, unsigned int line, const char* function ); bool try_lock( const char* file, unsigned int line, const char* function ); void unlock(); //... } And: void Engine::lock( const char* file, unsigned int line, const char* function ) { d->__engine_mutex.lock(); d->__locker.file = file; d->__locker.line = line; d->__locker.function = function; } bool Engine::try_lock( const char* file, unsigned int line, const char* function ) { bool locked = d->__engine_mutex.tryLock(); if ( ! locked ) { // Lock not obtained return false; } d->__locker.file = file; d->__locker.line = line; d->__locker.function = function; return true; } void Engine::unlock() { // Leave "d->__locker" dirty. d->__engine_mutex.unlock(); } -gabriel [1] http://gitorious.com/composite/composite/blobs/master/src/Tritium/Tritium/E… [2] http://gitorious.com/composite/composite/blobs/master/src/Tritium/src/Engin…