c++ - 如何克服 WaitForMultipleObjects 的 MAXIMUM_WAIT_OBJECTS 限制？

Question

由于 WaitForMultipleObjects 函数的 MAXIMUM_WAIT_OBJECTS 限制，我尝试编写自己的“等待线程”函数，但没有成功。你能给我一个提示，怎么做吗？

这是我的“等待线程”函数:

void WaitForThreads(std::set<HANDLE>& handles)
{
    for (int i = 0; i < SECONDSTOWAIT; i++)
    {
        // erase idiom
        for (std::set<HANDLE>::iterator it = handles.begin();
             it != handles.end();)
        {
            if (WaitForSingleObject(*it, 0) == WAIT_OBJECT_0)
                handles.erase(it++);
            else
                ++it;
        }
        if (!handles.size())
            // all threads terminated
            return;
        Sleep(1000);
    }
    // handles.size() threads still running
    handles.clear();
}

只要线程运行 WaitForSingleObject 就会返回 WAIT_TIMEOUT 但是当线程终止时返回值是 WAIT_FAILED 而不是 WAIT_OBJECT_0。我猜线程句柄不再有效，因为 GetLastError 返回 ERROR_INVALID_HANDLE。

MSDN 建议采用以下解决方案:

• Create a thread to wait on MAXIMUM_WAIT_OBJECTS handles, then wait on that thread plus the other handles. Use this technique to break the handles into groups of MAXIMUM_WAIT_OBJECTS.
• Call RegisterWaitForSingleObject to wait on each handle. A wait thread from the thread pool waits on MAXIMUM_WAIT_OBJECTS registered objects and assigns a worker thread after the object is signaled or the time-out interval expires.

但在我看来，两者都太过努力了。

编辑:线程是使用 MFC 函数 AfxBeginThread 创建的。返回的 CWinThread 指针仅用于获取关联的句柄。

CWinThread* thread = AfxBeginThread(LANAbfrage, par);
if ((*thread).m_hThread)
{
    threads.insert((*thread).m_hThread);
    helper::setStatus("%u LAN Threads active", threads.size());
}
else
    theVar->TraceN("Error: Can not create thread");

Answer 1

But it seems to me that both are too much effort.

如果您希望它与等待句柄一起工作，这就是您必须要做的。但是如果你需要的只是在所有线程完成之前阻塞的东西，你可以使用 Semaphore或者可能是 Synchronization Barrier .