.NET Console Application Exit Event

Question

In .NET, is there a method, such as an event, for detecting when a Console Application is exiting? I need to clean up some threads and COM objects.

I am running a message loop, without a form, from the console application. A DCOM component that I am using seems to require that the application pump messages.

I have tried adding a handler to Process.GetCurrentProcess.Exited and Process.GetCurrentProcess.Disposed.

I have also tried adding a handler to Application.ApplicationExit and Application.ThreadExit events, but they are not firing. Perhaps that is because I am not using a form.

Answer 1

You can use the ProcessExit event of the AppDomain:

class Program
{
    static void Main(string[] args)
    {
        AppDomain.CurrentDomain.ProcessExit += new EventHandler(CurrentDomain_ProcessExit);           
        // do some work

    }

    static void CurrentDomain_ProcessExit(object sender, EventArgs e)
    {
        Console.WriteLine("exit");
    }
}

Update

Here is a full example program with an empty "message pump" running on a separate thread, that allows the user to input a quit command in the console to close down the application gracefully. After the loop in MessagePump you will probably want to clean up resources used by the thread in a nice manner. It's better to do that there than in ProcessExit for several reasons:

• Avoid cross-threading problems; if external COM objects were created on the MessagePump thread, it's easier to deal with them there.
• There is a time limit on ProcessExit (3 seconds by default), so if cleaning up is time consuming, it may fail if pefromed within that event handler.

Here is the code:

class Program
{
    private static bool _quitRequested = false;
    private static object _syncLock = new object();
    private static AutoResetEvent _waitHandle = new AutoResetEvent(false);

    static void Main(string[] args)
    {
        AppDomain.CurrentDomain.ProcessExit += new EventHandler(CurrentDomain_ProcessExit);
        // start the message pumping thread
        Thread msgThread = new Thread(MessagePump);
        msgThread.Start();
        // read input to detect "quit" command
        string command = string.Empty;
        do
        {
            command = Console.ReadLine();
        } while (!command.Equals("quit", StringComparison.InvariantCultureIgnoreCase));
        // signal that we want to quit
        SetQuitRequested();
        // wait until the message pump says it's done
        _waitHandle.WaitOne();
        // perform any additional cleanup, logging or whatever
    }

    private static void SetQuitRequested()
    {
        lock (_syncLock)
        {
            _quitRequested = true;
        }
    }

    private static void MessagePump()
    {
        do
        {
            // act on messages
        } while (!_quitRequested);
        _waitHandle.Set();
    }

    static void CurrentDomain_ProcessExit(object sender, EventArgs e)
    {
        Console.WriteLine("exit");
    }
}