C# hang and stuck after Application.Run() at for loop

Question

Im building a program that surf to several websites and do something.

After surfing to like 5 urls successfully, the program hangs after the Application.Run() line. The program doesn't even enter the Handler function and just stuck. the CPU usage is 0 at this point.

I tried closing the threads in any possible way. What i'm doing wrong?

I'm doing it like that:

[STAThread]
private static void Main(string[] args) 
{
    for (int i = 0; i < urls.Count; i++) 
    {
        var th = new Thread(() = > 
        {
            var weBrowser = new WebBrowser();
            weBrowser.AllowNavigation = true;
            weBrowser.DocumentCompleted += Handler;
            weBrowser.Navigate(urls[i]);
            Application.Run();
        });
        th.SetApartmentState(ApartmentState.STA);
        th.Start();
        th.Join();
    }
}

And my Handle function is:

private static void Handler(object sender, WebBrowserDocumentCompletedEventArgs e) 
{
    WebBrowser weBrowser = sender as WebBrowser;
    var htmlDocument = weBrowser.Document;

    /*do something*/

    Application.Exit();
    Application.ExitThread();

    weBrowser.Dispose();
    weBrowser.Stop();

    Thread.CurrentThread.Abort();
}

My problem is very similar to this one: Application.Run() leads to application hanging

There is no answer in this question either.

Thanks!

Answer 1

I think you are doing several mistakes:

• you are joining inside the for look
• you are calling Application.Exit() in each handler call

You should move the joining outside the for loop and do not call Application.Exit.

The following sample seems to work well:

static class Program
{
  [STAThread]
  static void Main()
  {
     var urls = new List<string>() { 
        "http://stackoverflow.com",
        "http://stackoverflow.com",
        "http://stackoverflow.com",
        "http://stackoverflow.com",
        "http://stackoverflow.com",
        "http://stackoverflow.com",
        "http://stackoverflow.com",
        "http://stackoverflow.com"};

     var threads = new Thread[urls.Count];

     for (int i = 0; i < urls.Count; i++)
     {
        threads[i] = new Thread((url) =>
        {
           var weBrowser = new WebBrowser();
           weBrowser.AllowNavigation = true;
           weBrowser.DocumentCompleted += Handler;
           weBrowser.Navigate(url as string);
           Application.Run();
        });
        threads[i].SetApartmentState(ApartmentState.STA);
        threads[i].Start(urls[i]);
     }

     foreach (var t in threads)
        t.Join();

     Application.EnableVisualStyles();
     Application.SetCompatibleTextRenderingDefault(false);
     Application.Run(new Form1());
  }

  private static void Handler(object sender, WebBrowserDocumentCompletedEventArgs e)
  {
     WebBrowser weBrowser = sender as WebBrowser;

     var htmlDocument = weBrowser.Document;

     /*do something*/

     Application.ExitThread();

     weBrowser.Dispose();
     weBrowser.Stop();
  }
}