我们有一个WPF忙窗口指示器。它使用window.ShowDialog()显示在主线程上。响应Loaded事件后，将执行操作并关闭窗口，以便应用程序继续其工作。window.ShowDialog()似乎不时挂起(很少)，而没有显示对话框，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，我可以在
window.ShowDialog()方法上看到指令指针，但是该窗口在应用程序上不可见并且backgroundWorker尚未启动，因此我的猜测是尚未引发OnLoaded事件。该应用程序并未真正挂起，因为它可以正确重绘，但是您无法在屏幕上的任何位置单击。作为应用程序挂起时的一个怪异效果，它会在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#
正如其他人所说的那样，它看起来像是死锁，所以我在Visual Studio中进行了转储，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)
只有一个线程带有应用程序代码(0，使用ShowDialog调用管理1)。其他线程没有应用程序代码，线程15(托管10)是唯一带有某些.Net代码的线程。
看一下线程15(托管10)，因为它是一个有锁的线程，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]]
这个调用栈看起来像一个计时器，等待着被解雇给我，但是也许我对这种解释是错误的，所以我不知道该如何继续。
我可以根据要求提供您需要的任何信息。我不是WinDbg的专家，但我已经开始能够处理它，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，我们具有以下额外信息:
问题在于调用了
dispatcher.Invoke(new Action(window.Close));方法，并且该方法执行时未引发异常，但是window.ShowDialog();方法未返回。我们已经尝试使用Spy++和类似工具来查找窗口，据我所知，该窗口不存在，但
window.ShowDialog();仍在执行。我希望这可以使您对正在发生的事情有所了解。
最佳答案
一年后，我找到了问题的根源，以下代码显示了正在发生的事情的概念证明:
总结(由于真实代码中的竞争条件)，存在3个带有父子关系(A-> B-> C)的窗口，并且代码正在关闭B。这在WPF应用程序上有效(并且C得到也关闭了)，但在VSTO加载项中不起作用并挂起，B从不离开ShowDialog方法:
为Office Word 2010创建一个新的VSTO项目，并粘贴以下代码(不确定如果定位到其他Office版本会发生什么情况):
using System.Diagnostics;
using System.Windows;
using System.Windows.Interop;
using Action = System.Action;
namespace WordAddIn1HangTest
{
public partial class ThisAddIn
{
private void ThisAddIn_Startup(object sender, System.EventArgs e)
{
Window window1 = new Window();
window1.Content = "1";
Window window2 = new Window();
window2.Content = "2";
WindowInteropHelper windowInteropHelper1 = new WindowInteropHelper(window1);
WindowInteropHelper windowInteropHelper2 = new WindowInteropHelper(window2);
System.Windows.Threading.Dispatcher.CurrentDispatcher.BeginInvoke(new Action(() =>
{
windowInteropHelper1.Owner = Process.GetCurrentProcess().MainWindowHandle;
window1.ShowDialog();
MessageBox.Show("Hello");
}));
System.Windows.Threading.Dispatcher.CurrentDispatcher.BeginInvoke(new Action(() =>
{
windowInteropHelper2.Owner = windowInteropHelper1.Handle;
window2.ShowDialog();
}));
System.Windows.Threading.Dispatcher.CurrentDispatcher.BeginInvoke(new Action(() =>
{
window1.Close();
}));
}
private void ThisAddIn_Shutdown(object sender, System.EventArgs e)
{
}
#region VSTO generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InternalStartup()
{
this.Startup += new System.EventHandler(ThisAddIn_Startup);
this.Shutdown += new System.EventHandler(ThisAddIn_Shutdown);
}
#endregion
}
}
当window1关闭时，您应该会看到消息“Hello”。取而代之的是，您看不到任何窗口打开，并且ShowDialog调用被挂起。
关于.net - ShowDialog方法挂起而没有显示窗口??死锁？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/40304161/