I have an application that start System.Threading.Timer, then this timer every 5 seconds read some information from a linked database and update GUI on main form of application;
Since the System.Threading.Timer create another thread for the Tick event, i need to use Object.Invoke for updating User Interface on the main Form of application with code like this :
this.Invoke((MethodInvoker)delegate()
{
label1.Text = "Example";
});
The app work very well, but sometimes when the user close the main form and then close the application, if the second thread on timer_tick event is updating the user interface on main thread the user get an ObjectDisposedException.
How can i do for stop and close the threading timer before closing the main form and avoiding then Object disposed exception ?
System.Timers.Timer is a horrible class. There is no good way to stop it reliably, there is always a race and you can’t avoid it. The problem is that its Elapsed event gets raised from a threadpool thread. You cannot predict when that thread actually starts running. When you call the Stop() method, that thread may well have already been added to the thread pool but didn’t get around to running yet. It is subject to both the Windows thread scheduler and the threadpool scheduler.
You can’t even reliably solve it by arbitrarily delaying the closing of the window. The threadpool scheduler can delay the running of a thread by up to 125 seconds in the most extreme cases. You’ll reduce the likelihood of an exception by delaying the close by a couple of seconds, it won’t be zero. Delaying the close for 2 minutes isn’t realistic.
Just don’t use it. Either use System.Threading.Timer and make it a one-shot timer that you restart in the event handler. Or use a System.Windows.Forms.Timer, it is synchronous.
A WF Timer should be your choice here because you use Control.Invoke(). The delegate target won’t start running until your UI thread goes idle. The exact same behavior you’ll get from a WF timer.