MFC主线程使用WaitForSingleObject阻塞的问题

来源：互联网发布：java 读取cad文件 dwg 编辑：程序博客网时间：2024/06/05 04:38

在MFC程序的主线程中如果使用WaitForSingleObject等线子线程，而子线程里使用了有关于消息的函数，比如SetWindowText,InsertItem,SetItemText这些函数，就有会导致主主线程阻塞问题，看看这段代码。

DWORD WINAPI ThreadProc(LPVOID lpParameter   // thread data){CMFCWaitThreadDlg *pDlg = (CMFCWaitThreadDlg*)lpParameter;for (int i=0;i<=10;i++){OutputDebugStringA("test");Sleep(2000);pDlg->SetWindowText(_T("HEHE"));}return true;}void CMFCWaitThreadDlg::OnBnClickedOk(){// TODO: 在此添加控件通知处理程序代码DWORD dwID;HANDLE hThread;hThread = CreateThread(0,0,ThreadProc,this,0,&dwID);DWORD dwRet = WaitForSingleObject(hThread,INFINITE);if (dwRet == WAIT_OBJECT_0){MessageBoxA(0,"Thread exit",0,0);}}

主线程出现阻塞问题的原因是，因为SetWindowText调用了SendMessage,借助了消息循环，然后主线程又Waitxxxxx，必然会阻塞，最终导致工作线程Crash掉了。还好微软提供了另一个函数MsgWaitForMultipleObjects，用这个就能搞定了，看看下面这段代码，把WaitForSingleObject那一段给替换了，跑一跑试试，就没问题了。

DWORD WINAPI ThreadProc(LPVOID lpParameter   // thread data){CMFCWaitThreadDlg *pDlg = (CMFCWaitThreadDlg*)lpParameter;for (int i=0;i<=10;i++){OutputDebugStringA("test");Sleep(2000);pDlg->SetWindowText(_T("HEHE"));}return true;}void CMFCWaitThreadDlg::OnBnClickedOk(){// TODO: 在此添加控件通知处理程序代码DWORD dwID;HANDLE hThread;hThread = CreateThread(0,0,ThreadProc,this,0,&dwID);while(TRUE){DWORD result ; MSG msg ; result = MsgWaitForMultipleObjects(1, &hThread, FALSE, INFINITE, QS_ALLINPUT); if (result == (WAIT_OBJECT_0)){break;} else { PeekMessage(&msg, NULL, 0, 0, PM_REMOVE);DispatchMessage(&msg); } }MessageBoxA(0,"Thread exit",0,0);}

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