Using threads in C# winform solution but its not aborting

Question

I am using thread to multi tasks in winform solution, trying to abort the thread while its working but its not aborting, here is , is there any solution for this situation? need to make the thread abort/quit smoothly without any issues !

also is there any idea of how I can make the thread pause/resume?

Thanks in advance!

Thread CommentingThread;
     CommentingThread = new Thread(async () =>
    {

        AddLog("Commenting process has been started!");

        if (CommentBTN.InvokeRequired)
        {
            CommentBTN.Invoke((MethodInvoker)delegate () {




                CommentBTN.Text = "Stop"; });
        }
        else
        {
            CommentBTN.Text = "Stop";
        }

        if (UrlListview.InvokeRequired)

        {

            if (UrlListview.InvokeRequired)
            {
                UrlListview.Invoke((MethodInvoker)async delegate ()
                {



                    foreach (ListViewItem item in UrlListview.Items)
                    {
                        XtraMessageBox.Show(item.Text);
                        int timetodelay = RandomNumber.Next(int.Parse(CommentsMinDelayNumric.Value.ToString()), int.Parse(CommentsMaxDelayNumric.Value.ToString()));
                        await Task.Run(async () =>
                        {

                            await Task.Delay(timetodelay * 1000);

                        });

                    }
                    CommentBTN.Text = "Start";
                    AddLog("Commenting process has been finished sucessfully!");

                });
            }



        }
        else
        {
            foreach (ListViewItem item in UrlListview.Items)
            {
                XtraMessageBox.Show(item.Text);
                int timetodelay = RandomNumber.Next(int.Parse(CommentsMinDelayNumric.Value.ToString()), int.Parse(CommentsMaxDelayNumric.Value.ToString()));
                await Task.Run(async () =>
                {

                    await Task.Delay(timetodelay * 1000 );

                });

            }

                CommentBTN.Text = "Start";
            AddLog("Commenting process has been finished sucessfully!");



        }






        #endregion
    });
    CommentingThread.Start();

    if (CommentBTN.Text == "Stop")
    {
        CommentBTN.Text = "Start";
        CommentingThread.Abort();

        AddLog("Commenting process has been stopped!");


    }

Answer 1

First of all, looking at your code, it seems that the Thread may stop immediately if UrlListview.Items does not contain any elements. You might be missing a while loop in this case.

Regarding the issue of stopping the thread: Calling CommentingThread.Abort() will raise a ThreadAbortException which effectively crashes the thread (see the Microsoft Docs for more info for more info. To shut a thread down gracefully you should either declare CancellationTokenSource or a boolean which can be set to true (or false, depending on your implementation), to notify the thread that it needs to be stopped. Here is an example:

var myThread_ctoks = new CancellationTokenSource();
Thread myThread = new Thread( async () =>
{
    while (!myThread_ctoks.IsCancellationRequested) // simulate many long actions
    {
        await Task.Delay(TimeSpan.FromSeconds(2));
        Console.WriteLine("Iteration finished!");
    }
});
myThread.Start();  // start the thread

await Task.Delay(TimeSpan.FromMinutes(1));  // lets do some other work
myThread_ctoks.Cancel(); // and now shut down the thread

This thread checks every 2 seconds if a shutdown is required (because the simulated action takes that long). As soon as cancellation is requested (myThread_ctoks.IsCancellationRequested is set to true), the while condition will be false and thus the thread will end. The benefit of doing it this way is that the thread will be shut down in a safe, defined way as it actually shuts down gracefully and doesn't crash.

Regarding how you could pause and resume a thread. You could also use a variable to control that, just by checking if the thread is allowed to do work or not. If it should pause then you would just wait for a second in a while loop.

There is also the possibility to use Thread.Suspend() and Thread.Resume(). There is however the possibility, according to Microsoft that you could lock up other threads under certain circumstances. Additionally, you do not know exactly what code is being executed when you interrupt it. Which may lead to further unexpected behaviour. Thats why I am thinking its best to use a variable to control the thread behaviour.