MFC UI 线程中的进度条被阻止

Question

对于工作中的 MFC 项目，我必须在单独的 UI 线程 (CWinThread) 中创建进度条对话框 (CProgressCtrl)。我从网站http://adilevin.wordpress.com/2009/06/29/user-interface-threads-in-mfc/ 中举了一个例子。它自己工作。 （基本上，它有两个进度条，一个来自主 gui 线程，一个在单独的 ui 线程中创建。示例演示了在主 gui 线程中执行的计算不会干扰在 ui 线程中创建的进度条）

但是当我将代码放入我的应用程序时，进度条卡在了对 CProgressCtrl 的 SetPos 调用中。当我冻结主线程时（在它运行计算时），我从 Visual Studio 得到消息

进程似乎已死锁（或未运行任何用户模式 代码）。所有线程都已停止。

所以看起来 UI 线程正在等待来自主线程的东西？但我不知道它在等什么。这是卡住的ui线程的调用堆栈。

user32.dll!GetPropW()  + 0x72 bytes 
[Frames below may be incorrect and/or missing, no symbols loaded for user32.dll]    
user32.dll!SendMessageW()  + 0x4c bytes 
uxtheme.dll!DrawThemeParentBackgroundEx()  + 0x114 bytes    
comctl32.dll!GetEffectiveClientRect()  + 0x28f0 bytes   
comctl32.dll!GetEffectiveClientRect()  + 0x2916 bytes   
comctl32.dll!GetEffectiveClientRect()  + 0x2af3 bytes   
comctl32.dll!GetEffectiveClientRect()  + 0x2a25 bytes   
comctl32.dll!GetEffectiveClientRect()  + 0x2992 bytes   
user32.dll!gapfnScSendMessage()  + 0x270 bytes  
user32.dll!gapfnScSendMessage()  + 0x922 bytes  
user32.dll!FillRect()  + 0x110 bytes    
user32.dll!CallWindowProcA()  + 0x1b bytes  
mfc100d.dll!CWnd::DefWindowProcA(unsigned int nMsg=15, unsigned int wParam=0, long lParam=0)  Line 1089 + 0x20 bytes    C++
mfc100d.dll!CWnd::WindowProc(unsigned int message=15, unsigned int wParam=0, long lParam=0)  Line 2088 + 0x1c bytes C++
mfc100d.dll!AfxCallWndProc(CWnd * pWnd=0x08156d68, HWND__ * hWnd=0x00012452, unsigned int nMsg=15, unsigned int wParam=0, long lParam=0)  Line 257 + 0x1c bytes C++
mfc100d.dll!AfxWndProc(HWND__ * hWnd=0x00012452, unsigned int nMsg=15, unsigned int wParam=0, long lParam=0)  Line 420  C++
cv32.dll!AfxWndProcDllStatic(HWND__ * hWnd=0x00012452, unsigned int nMsg=15, unsigned int wParam=0, long lParam=0)  Line 54 + 0x15 bytes    C++
user32.dll!gapfnScSendMessage()  + 0x270 bytes  
user32.dll!GetDC()  + 0x52 bytes    
user32.dll!GetWindowLongW()  + 0x18a bytes  
user32.dll!GetDC()  + 0xab bytes    
ntdll.dll!KiUserCallbackDispatcher()  + 0x2e bytes  
comctl32.dll!GetEffectiveClientRect()  + 0x2660 bytes   
comctl32.dll!RegisterClassNameW()  + 0x37e bytes    
user32.dll!gapfnScSendMessage()  + 0x270 bytes  
user32.dll!gapfnScSendMessage()  + 0x922 bytes  
user32.dll!FillRect()  + 0x110 bytes    
user32.dll!CallWindowProcA()  + 0x1b bytes  
mfc100d.dll!CWnd::DefWindowProcA(unsigned int nMsg=1026, unsigned int wParam=65, long lParam=0)  Line 1089 + 0x20 bytes C++
mfc100d.dll!CWnd::WindowProc(unsigned int message=1026, unsigned int wParam=65, long lParam=0)  Line 2088 + 0x1c bytes  C++
mfc100d.dll!AfxCallWndProc(CWnd * pWnd=0x08156d68, HWND__ * hWnd=0x00012452, unsigned int nMsg=1026, unsigned int wParam=65, long lParam=0)  Line 257 + 0x1c bytes  C++
mfc100d.dll!AfxWndProc(HWND__ * hWnd=0x00012452, unsigned int nMsg=1026, unsigned int wParam=65, long lParam=0)  Line 420   C++
cv32.dll!AfxWndProcDllStatic(HWND__ * hWnd=0x00012452, unsigned int nMsg=1026, unsigned int wParam=65, long lParam=0)  Line 54 + 0x15 bytes C++
user32.dll!gapfnScSendMessage()  + 0x270 bytes  
user32.dll!gapfnScSendMessage()  + 0x922 bytes  
user32.dll!GetWindow()  + 0x21a bytes   
user32.dll!SendMessageA()  + 0x4c bytes 
mfc100d.dll!CProgressCtrl::SetPos(int nPos=65)  Line 363 + 0x46 bytes   C++
cv32.dll!CProgressCtrlWithTimer::OnTimer(unsigned int nIDEvent=1)  Line 1577    C++

有人知道什么是错的吗？

当我自己运行示例应用程序时，它不会调用 uxtheme.dll，因为它没有在示例中使用。最后一个 SendMessageW 可能是问题吗？

Answer 1

SetPos 表示对 SendMessage 的调用，这是一个阻塞调用。您必须绝不跨线程边界调用SendMessage，因为这注定会导致死锁。

如果需要更新主线程上运行的GUI，必须使用PostMessage：

PostMessage(hWndMain, UWM_MYMESSAGE, progress, 0);

并在主线程中处理消息：

LRESULT OnMyMessage(WPARAM wParam, LPARAM lParam)
{
   m_progress.SetPos((int)wParam);
   return 1;
}