Hello, the email with the 'ThreadPool' subject requested an implemention of the synchronization channel between producer and consumer threads. I've a suggestion (adopted from several books) - the only problem is how to tell the consumer threads, that all producer have finished their jobs. You can signal it from outside (deactive member function) or each producer thread has to register on the message_queue (and unregister if it has finished its job). With best regards, Oliver <<test.cpp>> <<message_queue.h>>