套接字和multithreading

我有一个有趣的（对我来说）的问题…有两个线程，一个用于从stdinput捕获数据并通过套接字发送到服务器，另一个从阻塞套接字接收数据。 所以，当没有从服务器的答复，recv（）调用等待无限的权利？ 但不是只阻塞其调用线程，而是阻止整个过程！ 为什么这件事发生？

boost::mutex nvtMutex; boost::mutex strMutex; boost::mutex quitMutex; bool quit = false; void *processServerOutput(void *arg) { NVT *nvt = (NVT*)arg; while(1) { // Lock the quitMutex before trying to access to quit variable quitMutex.lock(); if(quit) { quitMutex.unlock(); pthread_exit(NULL); } else quitMutex.unlock(); // Receive output from server nvtMutex.lock(); nvt->receive(); cout << Util::Instance()->iconv("koi8-r", "utf-8", nvt->getOutBuffer()); nvtMutex.unlock(); // Delay sleep(1); } } void *processUserInput(void *arg) { NVT *nvt = (NVT*)arg; while(1) { // Get user's input //cin.getline(str, 1023); sleep(3); strcpy(str, "hello"); // If we type 'quit', exit from thread if(strcmp(str, "quit") == 0) { // Lock quit variable before trying to modify it quitMutex.lock(); quit = true; quitMutex.unlock(); // Exit from thread pthread_exit(NULL); } // Send the input to server nvtMutex.lock(); nvt->writeUserCommand(Util::Instance()->iconv("utf-8", "koi8-r", str)); nvt->send(); nvtMutex.unlock(); } }