循环工作线程而不阻塞它们

Question

你好，有没有办法运行一组线程（不阻塞它们）并在主线程发出信号时停止？

例如在这个线程回调中：

void *threadCallback ( void * threadID) {
    syncPrint("Thread %lu started . Waiting for stop signal\n", threadID);
    pthread_mutex_lock(&stopSignalGuard);
    int i = 0;
    while(!stopSignal) {
        i++;
        syncPrint("increment : %d \n",i);
        pthread_cond_wait(&stopCondition,&stopSignalGuard);
    }
    syncPrint("Stop signal received. Thread %lu will terminate...\n",(long)threadID);
    pthread_mutex_unlock(&stopSignalGuard);
    pthread_exit(NULL);
}

据我所知，while 循环没有有效运行。 pthread_cond_wait(...) 阻止了执行。有可能运行这个循环，直到主线程发出停止的信号？或者是另一种方法来做到这一点？

谢谢！

Answer 1

如果在某些条件发生变化之前线程无法继续前进，您只需要使用 pthread_cond_wait()。

在你的例子中，线程显然还有其他它可以做的事情，所以你只需检查互斥锁保护部分中的标志，然后继续：

int getStopSignal(void)
{
    int stop;

    pthread_mutex_lock(&stopSignalGuard);
    stop = stopSignal;
    pthread_mutex_unlock(&stopSignalGuard);

    return stop;
}       

void *threadCallback (void * threadID)
{
    int i = 0;

    syncPrint("Thread %lu started . Waiting for stop signal\n", threadID);

    while(!getStopSignal()) {
        i++;
        syncPrint("increment : %d \n",i);
    }

    syncPrint("Stop signal received. Thread %lu will terminate...\n",(long)threadID);
    pthread_exit(NULL);
}

循环工作线程而不阻塞它们

Looping an workers threads without blocking them

multithreading

pthreads

threadpool