c++ - pthread_join() 在 ios 上失败

Question

我正在做一个关于 IOS 的多线程项目。在我的项目中，pthread 连接有时会失败。

pthread_join(thread_id, NULL) == 0

注意：这仅在 IOS 上发生，并且是随机的。连接操作失败的原因可能是什么。

Answer 1

手册页说：

错误 pthread_join() 在以下情况下将失败：

 [EDEADLK]          A deadlock was detected or the value of thread speci-
                    fies the calling thread.

 [EINVAL]           The implementation has detected that the value speci-
                    fied by thread does not refer to a joinable thread.

 [ESRCH]            No thread could be found corresponding to that speci-
                    fied by the given thread ID, thread.

Answer 2

我遇到了同样的问题，并找到了一个简单的解决方案：不要调用 pthread_detach()。根据文档，pthread_detach 将胎面移动到无法再连接的状态，因此 pthread_join 失败并显示 EINVAL。

源代码可能如下所示：

pthread_t       thread;
pthread_attr_t  threadAttr;

bool run = true;
void *runFunc(void *p) {
    while (run) { ... }
}

- (void)testThread {
    int status = pthread_attr_init(&threadAttr);
    NSLog(@"pthread_attr_init status: %d", status);
    status = pthread_attr_setdetachstate(&threadAttr, PTHREAD_CREATE_JOINABLE);
    NSLog(@"pthread_attr_setdetachstate status: %d", status);
    status = pthread_create(&thread, &threadAttr, &runFunc, (__bridge void *)self);
    NSLog(@"pthread_create status: %d", status);
    /* let the thread run ... */
    run = false;
    status = pthread_join(thread, NULL);
    NSLog(@"pthread_join status: %d == %d, ?", status, EINVAL);
}