The function int pthread_detach(pthread_t thread); detaches a thread. It shall indicate to the implementation that storage for 'thread' can be reclaimed when that thread terminates. If 'thread' has not terminated, pthread_detach() won't cause it to terminate. The effect of multiple pthread_detach() calls on the same target thread is unspecified. If success, it returns 0; Upon failure, it returns an error number: -[EINVAL] 'thread' does not refer to a joinable thread. -[ESRCH] No thread could be found corresponding to that thread ID It shall not return [EINTR]