Cancel the task

Question

With the API： CancellationTokenSource .Cancel()  cannot cancel the task as I want.

Follow is my codes:

        private async void StartWork()
        {
            _token = new CancellationTokenSource(3000);
            await System.Threading.Tasks.Task.Run(new Action(DoWork), _token.Token);
        }

        private async void DoWork()
        {
            //_token.Cancel();
            while (true)
            {
                await System.Threading.Tasks.Task.Delay(1000);
                System.Diagnostics.Debug.WriteLine(">>");
            }
        }

The task will not stop in 3 seconds. Why?

---

Ray_ni

Answer 1

Try passing the token to the delay task..

await System.Threading.Tasks.Task.Delay(1000, _token.Token);

an OperationCancelledException will be thrown after 3 secs.

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http://babaandthepigman.spaces.live.com/blog/

Answer 2

Well,  this is a good way to console my problem.

But if there is no Task.Delay in my task code, How could I do?

---

Ray_ni

Answer 3

The cancellation token is a request for the task to cancel. In your task you'll need to look at the token to see if it IsCancellationRequested has been set. If it has been set, then cancel out of the task.

See Cancellation in Managed Threads

--Rob

Answer 4

Well, you means, I need to cancel the task by myself ?

---

Ray_ni

Answer 5

Yes. Only you know when and how your task can be cancelled, so you will have to write the code to check that and cancel out.

--Rob