Cancelling a Blocked Pthread

How do I cause a thread to respond to pthread_cancel开发者_如何学JAVA() if it is blocked on a sem_wait()?

You can set a signal handler, let's says for SIGUSR1, for the thread that will be blocking then, from another thread, you call pthread_cancel(tid) and pthread_kill(tid, SIGUSR1). The thread will be canceled once sem_wait() is interrupted by the signal.