CODEWITHSUNDEEP
.netmultithreadingbackgroundworker
oli.G
oli.G

Reputation: 1350

.NET app not closing

I have a fairly WPF application with a strange behavior: after I close it when debugging, the window gets closed but the debug (so the app itself) is still running. I'm talking about clicking the close button on the window - forcing shutdown by clicking Stop Debugging works.

I guess some background thread is still running even when the UI thread finished. I don't have any multi-threaded code using the Thread class, however I'm using a library called Ookii.Dialogs which contains a ProgressWindow class that is used much like the good old BackgroundWorker. This class is my primary suspect, however I believe I'm using it correctly - just handling long-running operations in the DoWork handler, showing progress by calling ReportProgress, and starting them with the Show() method, which is something like RunWorkerAsync, but it also displays a progress window. When the operation finished, the window is automatically closed.

Let's say it's not the library's fault and replacing it with a BackgroundWorker (which would be the same, only without the progress window) would still show the same symptoms. Any idea how I could begin to diagnose this?

Upvotes: 2

Views: 282

Answers (3)

oli.G
oli.G

Reputation: 1350

Found it! The problem was I created a window instance that was never showed. This is what I had:

private CustomWindow myWindow;

public MainWindow() {
    this.myWindow = new CustomWindow();    
}

public void Button_Click(object sender, RoutedEventArgs e) {
    this.myWindow.Show();
}

Even if I never clicked the button (so the window was never showed), a Window instance was still created and left waiting in memory. This prevented the app from shutting down.

Changing the code like this fixed the problem:

private CustomWindow myWindow;

public MainWindow() {

}

public void Button_Click(object sender, RoutedEventArgs e) {
    this.myWindow = new CustomWindow();   
    this.myWindow.Show();
}

The window is now created only at the point when it needs to be displayed (which is a better way to go anyway), and when it is displayed, it can be actually properly closed - unlike in the first case, when not clicking the button left the window in a weird, "created but never actually displayed nor closed" state, which prevented the app from shutting down, since, as crashmstr pointed out, my App had a default ShutdownMode of OnLastWindowClose.

Upvotes: 1

crashmstr
crashmstr

Reputation: 28573

Not sure if you have the same problem, but the same kind of this happened to us. In your Application class, try setting ShutdownMode = ShutdownMode.OnMainWindowClose. the default is last window (even though there were no windows open, this was still a problem).

MSDN Documentation for Shutdownmode

public partial class App : Application
{
   protected override void OnStartup(StartupEventArgs args)
   {    
      ///Set this to OnMainWindowClose (defaults to OnLastWindowClose)
      ///This seems to prevent the app from running after the main window closes
      ///--alternate solution would be to call Application.Current.Shutdown() from  MainWindow.OnClosing
      ShutdownMode = ShutdownMode.OnMainWindowClose;
   }
}

Upvotes: 1

Emond
Emond

Reputation: 50682

Attach Visual Studio to the running process and pause it.

Have a look at the threads and what it is they are doing.

Upvotes: 1

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