Question

Here’s what I have. When my application starts up, it creates a thread and runs my startListening() function. But what it seems to do, is run any other functions called within startListening under the same thread. Is there a way I can make it so that ONLY the things immediately inside of startListening are ran with that thread, and not the functions called from within that?

It would just make it a lot easier for me when referencing controls and things that aren’t within that thread so I don’t have to Invoke each time.

EDIT: Maybe this isn’t the right thing to be asking. I know I had to Invoke with setting textboxes, but now I need to make a timer enabled. Its not throwing any exceptions when I try to enable it, but rather just not “ticking”. Here’s my code:

    private void beginListenerThread()
    {
        Thread thread1 = new Thread(startListening);
        thread1.Start();
    }

    private void startListening()
    {
        timer1.enabled = true;
    }

But it doesn’t tick.

Thanks!

Answer 1

Yes, this is the kind of trouble you’ll run into when you use a class that is not thread-safe on a thread. The Winforms Timer class generates Tick events from a little hidden helper window, a window that receives WM_TIMER messages generated by the Windows SetTimer() api function and turns them into Tick event calls. That window is created when you enable the timer.

What goes wrong here is that this window gets created on the wrong thread. It needs a message pump to dispatch the WM_TIMER notifications, that thread doesn’t have one. It could have one by calling Application.Run() but you don’t want to go there.

Follow the advice given in the MSDN Library article’s Remarks section:

The Windows Forms Timer component is single-threaded, and is limited to an accuracy of 55 milliseconds. If you require a multithreaded timer with greater accuracy, use the Timer class in the System.Timers namespace.

Or the System.Threading.Timer class, a timer class that’s a bit less cranky.