Process lingering around after application quit

Adwait

19y3.6kC#

When I run my windows application, a main form is loaded. I then fire another thread which keeps scanning for some RFIDs. When the RFID scanning is done I stop the process by simply setting a boolean variable to true. So that later I can resume it when needed.
Soemthing like
while(!StopThread)
{
.... my thread code
}

When someone clicks Alt + F4 on the main window, the form closes down. But I still have a process running in my task manager. This has to do with the thread that I fired because if I disable it, the application shuts down clean.

Here is what I tried and did not work.

1. I set the boolean variable to true so that the thread function stopes. I then tried calling m_workerThread.Abort() and handled a excetion for ThreadAbortException. Then in the finally block I put m_workerThread.Join(). I also tried removing the join.
2. In the dispose of the main form, I tried to do a getprocessbyname and kill that process if its running. That did not work either.

Can someone please tell me why would this be happening and whats the clean way to solve this problem ?
Adwait

5 Replies

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Alan19y ago
The usual objection to using Environment.Exit in a Windows Forms application is that it's more abrupt than Application.Exit and the latter should therefore be preferred for a more orderly shutdown.

However, as you've already cleaned up, I don't think that Enviroment.Exit will do any harm here and it may be the only way you can force the entire process to terminate as Application.Exit doesn't appear to stop non-UI threads.
Adwait19y ago
That actually worked. But the question is whats the harm in doing that ?I am doing that in dispose at the end of everything so it should be save to exit out of the app at this point of time.
Adwait
Alan19y ago
I know this is an odd suggestion to make in a Winforms application, but I'd try placing a call to Environment.Exit(1) in either the form's FormClosing or FormClosed eventhandlers in an attempt to force the whole process to close.
Adwait19y ago
there is no other event that will stop the RFID scan. I need to make sure that the RFID stops beforre the form is closed and I need to abort that thread manually since it wont abort automatically.
Alan19y ago
It might be better to prevent the user from closing the main form until RFID scanning is completed. You could do this by handling the main form's FormClosing event. For example:

private void frmMain_FormClosing(Object sender, FormClosingEventArgs e)
{
    if (ScanningThread.IsAlive)
    {
       e.Cancel = true; // cancel form closure
       MessageBox.Show("Unable to close form until RFID scanning completed");
    }
}