我们有一个WPF忙窗口指示器。它在主线程上使用window.ShowDialog()显示。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()似乎不时挂起（非常罕见）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，我可以看到window.ShowDialog()方法上的指令指针，但是窗口在应用程序上不可见，而且后台工作尚未启动，所以我的猜测是OnLoaded事件尚未被提升
应用程序并未真正挂起，因为它正确地重绘，但您无法单击屏幕上的任何位置。当应用程序挂起时它作为一个奇怪的效果从Windows 7上的任务栏消失。
我打破执行时看到的callstack是以下一个：
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#
正如其他人所说的看起来像死锁一样，所以我用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)
只有一个带有应用程序代码的线程（0，带有ShowDialog调用的托管1）。其他线程没有应用程序代码，线程15（托管10）是唯一一个带有.Net代码的线程。
查看线程15（托管10），因为它是带锁的那个我看到以下callstack：
[[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callstack看起来像一个等待被解雇的计时器，但也许我对这种解释是错的，所以我不知道如何继续这个。
我可以根据要求提供您需要的任何信息。我不是WinDbg的专家，但我开始能够处理它，所以你也可以让我用它来获取信息。
更新：
在向应用程序添加一些日志后，我们有以下额外信息：
问题是调用方法dispatcher.Invoke(new Action(window.Close));并且它在不抛出异常的情况下执行，但方法window.ShowDialog();不会返回。
我们试图找到使用Spy ++和类似工具的窗口，据我所知，窗口不存在，但window.ShowDialog();仍在执行。
我希望这可以让您了解正在发生的事情。
答案 0 :(得分：1)
可能会陷入僵局，但我们没有足够的信息可以开始（例如，Loaded事件处理程序中发生了什么，或者在什么情况下调用了事件。）
您的代码有些内容可能值得仔细研究：
您似乎没有设置模态对话框的所有者。在最坏的情况下，这可能会导致您的模态对话框显示在背景中，可能很难或无法解除。
目前还不清楚您在哪里创建窗口。 Loaded事件仅在您首次显示窗口时触发（与例如Activated事件相反）。如果您回收窗口，则不会触发加载的事件，也不会启动后台工作程序。
这是一个非常基本的工作WPF示例，包含一个带有boackground worker的主窗口和一个模态进度对话框。我试着从这里开始试图找出问题。
<强> MainWindow.xaml
<Window x:Class="ProgressBarSample.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
Title="MainWindow"
Width="200"
Height="100"
mc:Ignorable="d">
<Grid>
<Button Click="OnButtonClick">Start</Button>
</Grid>
</Window>
<强> MainWindow.xaml.cs
using System.ComponentModel;
using System.Threading;
using System.Windows;
namespace ProgressBarSample
{
public partial class MainWindow
{
private BackgroundWorker _backgroundWorker;
private ProgressWindow _progressWindow;
public MainWindow()
{
InitializeComponent();
}
private void OnButtonClick(object sender, RoutedEventArgs e)
{
_progressWindow = new ProgressWindow { Owner = this };
_backgroundWorker = new BackgroundWorker { WorkerReportsProgress = true };
_backgroundWorker.DoWork += OnWorkerDoWork;
_backgroundWorker.RunWorkerCompleted += OnWorkerRunWorkerCompleted;
_backgroundWorker.ProgressChanged += OnWorkerProgressChanged;
_backgroundWorker.RunWorkerAsync();
_progressWindow.ShowDialog();
}
private void OnWorkerProgressChanged(object sender, ProgressChangedEventArgs e)
{
_progressWindow.ProgressValue = e.ProgressPercentage;
}
private void OnWorkerRunWorkerCompleted(
object sender,
RunWorkerCompletedEventArgs e)
{
_progressWindow.Close();
MessageBox.Show("Done");
}
private void OnWorkerDoWork(object sender, DoWorkEventArgs e)
{
int initialValue = 100;
for (int i = 0; i < initialValue; i++)
{
Thread.Sleep(50);
_backgroundWorker.ReportProgress(i);
}
}
}
}
<强> ProgressWindow.xaml
<Window x:Class="ProgressBarSample.ProgressWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
Title="Progress"
Width="300"
Height="100"
mc:Ignorable="d">
<Grid>
<ProgressBar Maximum="100" Minimum="0"
Value="{Binding ProgressValue}" />
</Grid>
</Window>
<强> ProgressWindow.xaml.cs
using System.ComponentModel;
using System.Runtime.CompilerServices;
namespace ProgressBarSample
{
public partial class ProgressWindow : INotifyPropertyChanged
{
private double _progressValue;
public ProgressWindow()
{
InitializeComponent();
DataContext = this;
}
public double ProgressValue
{
get { return _progressValue; }
set
{
_progressValue = value;
OnPropertyChanged();
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(
[CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
}
答案 1 :(得分：1)
我发现问题的原因一年后，下面的代码显示了正在发生的事情的概念证明：
总结（由于实际代码中的竞争条件），有3个窗口具有父子关系（A - > B - > C），代码正在关闭B.这适用于WPF应用程序（和C也被关闭），但在VSTO加载项不起作用并挂起，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（不确定如果定位其他Office版本会发生什么）：
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＆＃34; Hello＆＃34;。而不是你没有看到任何窗口打开，ShowDialog调用挂起。
答案 2 :(得分：0)
callstack显示您的对话框在模态消息循环中等待消息。它没有被锁定或阻止。
正如Dirk指出的那样，Loaded事件并不总是被提升。这可能是他建议的两件事之一。
解决方法可以是在BusyIndicatorImpl中显式调用onLoaded。
private void BusyIndicatorImpl(Window window, RoutedEventHandler onLoaded)
{
onLoaded();
window.ShowDialog();
}
另外，您可以将其发布到模态对话框中。
private void BusyIndicatorImpl(Window window, RoutedEventHandler onLoaded)
{
window.Dispatcher.InvokeAsync(() => onLoaded(window, null));
window.ShowDialog();
}