pthread_join和pthread_detach

pthread_join(pthread_t thread, void **retval)

The pthread_join() function waits for the thread specified by thread to terminate.  If that thread has already terminated, then pthread_join() returns immediately.  The thread specified by thread must be joinable.

   pthread_join成功调用时，调用线程被阻塞，直到由thread指定的线程终止（如果线程已经终止，pthread_join会立即返回）

pthread_detach

The pthread_detach() function marks the thread identified by thread as detached.  When a detached thread terminates, its resources are automatically released back to the system without the need for another thread to join with the terminated thread.