How to prevent an exception in a background thread from terminating an application?

Question

I can hookup to AppDomain.CurrentDomain.UnhandledException to log exceptions from background threads, but how do I prevent them terminating the runtime?

Answer 1

Keeping the answer short, yes, you do can prevent the runtime from terminating.

Here is a demo of the workaround:

class Program
{
    void Run()
    {
        AppDomain.CurrentDomain.UnhandledException += new UnhandledExceptionEventHandler(CurrentDomain_UnhandledException);

        Console.WriteLine("Press enter to exit.");

        do
        {
            (new Thread(delegate()
            {
                throw new ArgumentException("ha-ha");
            })).Start();

        } while (Console.ReadLine().Trim().ToLowerInvariant() == "x");


        Console.WriteLine("last good-bye");
    }

    int r = 0;

    void CurrentDomain_UnhandledException(object sender, UnhandledExceptionEventArgs e)
    {
        Interlocked.Increment(ref r);
        Console.WriteLine("handled. {0}", r);
        Console.WriteLine("Terminating " + e.IsTerminating.ToString());

        Thread.CurrentThread.IsBackground = true;
        Thread.CurrentThread.Name = "Dead thread";            

        while (true)
            Thread.Sleep(TimeSpan.FromHours(1));
        //Process.GetCurrentProcess().Kill();
    }

    static void Main(string[] args)
    {
        Console.WriteLine("...");
        (new Program()).Run();
    }
}

Essentially, you just did not let the runtime to show the "... program has stopped working" dialog.

In case you need to log the exception and silently exit, you can call Process.GetCurrentProcess().Kill();