c - 如何在子线程之前执行父线程 - C中的pthreads

Question

我想让父进程在子线程之前执行。我不确定获取程序输出的顺序时哪里出错了。

int status = 0;

void *print_child(void *arg)
{

    while (status == 0)
    {
        printf("Signal hasn't changed..\n");
        sleep(1);

    }
    printf("The child has started...\n");
    printf("The child is done! \n ");
}

int main()
{
    pthread_t child;
    pthread_create(&child, NULL, &print_child, NULL);

    sleep(2);
    printf("The parent has started...\n");
    printf("The parent is done! \n");

    status++;

    if (pthread_join(child, NULL))
    {
        printf("ERROR");
        exit(1);
    }
}

输出:

signal has changed
signal has changed
parent has started
parent is done
child has started
child is done

Answer 1

排除并发执行的最简单方法是锁。让“父线程”(原始线程)在调用 pthread_create 之前获取锁定，并且仅在准备好“子线程”(新线程)运行时才解锁。 “ child ”在做任何事情之前都应该先拿到锁；如果需要，它可以立即解锁它，或者保留它以控制对共享状态的访问。