我们有一个 WPF 繁忙窗口指示器。它显示在主线程上,使用window.ShowDialog()
. 在响应 Loaded 事件时,将执行一个操作并关闭窗口,以便应用程序继续其工作。
window.ShowDialog()
似乎不时(非常罕见)挂起而不显示对话框,并且未触发 Loaded 事件,因此应用程序挂起。相关代码如下:
private void BusyIndicatorAsyncCall(string text, Action<DoWorkEventArgs> doWorkDinamicView = null, Action doWork = null, Action workCompleted = null, Action<Exception> exceptionReturn = null)
{
Window window = this.CreateWindowOfBusyIndicator(text);
Dispatcher dispatcher = window.Dispatcher;
BackgroundWorker backgoundworker = new BackgroundWorker();
IViewModel viewModel = (window.Content as UserControl).DataContext as IViewModel;
this.Modals.Add(viewModel, window);
if (doWorkDinamicView != null)
{
DoWorkEventArgs eventArgs = new DoWorkEventArgs(window.Content);
backgoundworker.DoWork += (s, e) => doWorkDinamicView.Invoke(eventArgs);
}
else if (doWork != null)
{
backgoundworker.DoWork += (s, e) => { doWork.Invoke(); };
}
backgoundworker.RunWorkerCompleted += (s, e) =>
{
Exception exception = e.Error;
if (exception == null)
{
if (workCompleted != null)
{
try
{
this.StyleName = null;
workCompleted.Invoke();
}
catch (Exception ex)
{
exception = ex;
}
}
}
this.Modals.Remove(viewModel);
dispatcher.Invoke(new Action(window.Close));
if (exception != null)
{
if (exceptionReturn == null)
throw new Exception("Error en RunWorkerCompleted.", exception);
else
exceptionReturn(exception);
}
};
RoutedEventHandler onLoaded = new RoutedEventHandler((sender, e) =>
{
try
{
backgoundworker.RunWorkerAsync();
}
catch
{
}
});
this.BusyIndicatorImpl(window, onLoaded);
}
private void BusyIndicatorImpl(Window window, RoutedEventHandler onLoaded)
{
window.Loaded += onLoaded;
window.ShowDialog();
window.Loaded -= onLoaded;
}
当应用程序挂起时,我可以看到window.ShowDialog()
方法上的指令指针,但窗口在应用程序上不可见,并且 backgroundWorker 尚未启动,所以我的猜测是 OnLoaded 事件尚未引发。
该应用程序并没有真正挂起,因为它正确重绘,但您无法单击屏幕上的任何位置。作为一个奇怪的副作用,当应用程序挂起时,它会从 Windows 7 的任务栏中消失。
我在中断执行时看到的调用堆栈如下:
user32.dll!_NtUserGetMessage@16() + 0x15 bytes
user32.dll!_NtUserGetMessage@16() + 0x15 bytes
[Managed to Native Transition]
WindowsBase.dll!MS.Win32.UnsafeNativeMethods.GetMessageW(ref System.Windows.Interop.MSG msg, System.Runtime.InteropServices.HandleRef hWnd, int uMsgFilterMin, int uMsgFilterMax) + 0x14 bytes
WindowsBase.dll!System.Windows.Threading.Dispatcher.GetMessage(ref System.Windows.Interop.MSG msg, System.IntPtr hwnd, int minMessage, int maxMessage) + 0x80 bytes
WindowsBase.dll!System.Windows.Threading.Dispatcher.PushFrameImpl(System.Windows.Threading.DispatcherFrame frame) + 0x75 bytes WindowsBase.dll!System.Windows.Threading.Dispatcher.PushFrame(System.Windows.Threading.DispatcherFrame frame) + 0x49 bytes
PresentationFramework.dll!System.Windows.Window.ShowHelper(object booleanBox) + 0x17d bytes
PresentationFramework.dll!System.Windows.Window.Show() + 0x5c bytes
PresentationFramework.dll!System.Windows.Window.ShowDialog() + 0x27d bytes
> xxx.dll!xxx.BusyIndicatorImpl(System.Windows.Window window, System.Windows.RoutedEventHandler onLoaded) Line 743 + 0xd bytes C#
正如其他人之前所说的那样,它看起来像一个死锁,所以我使用 Visual Studio 进行了转储,并在其上运行了一些工具来寻找死锁。这是应用程序正在运行的线程的信息:
Debugger Thread ID Managed Thread ID OS Thread ID Thread Object GC Mode Domain Lock Count Apt Exception
0 1 5684 2b2390 Preemptive 9176600 0 STA
6 2 5572 2c7a80 Preemptive 2a82f8 0 MTA (Finalizer)
7 3 3676 2cb828 Preemptive 2a82f8 0 Unknown
11 4 864 7f7d5c0 Preemptive 2a82f8 0 MTA (Threadpool Worker)
15 10 4340 921cdc8 Preemptive 9176600 1 MTA
16 12 1648 9438560 Preemptive 2a82f8 0 MTA (Threadpool Completion Port)
17 14 3380 9001038 Preemptive 2a82f8 0 Unknown (Threadpool Worker)
21 7 5336 9002fe8 Preemptive 2a82f8 0 MTA (Threadpool Worker)
20 5 4120 9003fc0 Preemptive 2a82f8 0 MTA (Threadpool Worker)
25 18 5172 9004508 Preemptive 2a82f8 0 MTA (Threadpool Worker)
27 11 5772 9003a78 Preemptive 2a82f8 0 MTA (Threadpool Worker)
应用程序代码只有一个线程(0,使用 ShowDialog 调用托管 1)。其他线程没有应用程序代码,线程 15(托管 10)是唯一有一些 .Net 代码的线程。
查看线程 15(托管 10),因为它是带锁的线程,我看到以下调用堆栈:
[[HelperMethodFrame_1OBJ] (System.Threading.WaitHandle.WaitMultiple)] System.Threading.WaitHandle.WaitMultiple(System.Threading.WaitHandle[], Int32, Boolean, Boolean)
mscorlib_ni!System.Threading.WaitHandle.WaitAny(System.Threading.WaitHandle[], Int32, Boolean)+92
System_ni!System.Net.TimerThread.ThreadProc()+28f
mscorlib_ni!System.Threading.ThreadHelper.ThreadStart_Context(System.Object)+6f
mscorlib_ni!System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)+a7
mscorlib_ni!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object, Boolean)+16
mscorlib_ni!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext, System.Threading.ContextCallback, System.Object)+41
mscorlib_ni!System.Threading.ThreadHelper.ThreadStart()+44
[[GCFrame]]
[[DebuggerU2MCatchHandlerFrame]]
[[ContextTransitionFrame]]
[[DebuggerU2MCatchHandlerFrame]]
这个调用堆栈看起来像一个等待被解雇的计时器,但也许我对这种解释错了,所以我不知道如何继续。
我可以根据要求提供您需要的任何信息。我不是 WinDbg 方面的专家,但我开始能够处理它,因此您也可以要求我获取有关它的信息。
更新 :
将一些日志添加到应用程序后,我们有以下额外信息:
问题是该方法dispatcher.Invoke(new Action(window.Close));
被调用并且它在没有抛出异常的情况下执行但该方法window.ShowDialog();
没有返回。
我们试图用 Spy++ 和类似工具找到窗口,据我所知,窗口不存在,但window.ShowDialog();
一直在执行。
我希望这能让您对正在发生的事情有所了解。