What is a cancel exception?

What is a cancel exception?

Exception indicating that the result of a value-producing task, such as a FutureTask , cannot be retrieved because the task was cancelled. Since: 1.5 See Also: Serialized Form.

How do you cancel a task?

In this article

1. Create and start a cancelable task.
2. Pass a cancellation token to your user delegate and optionally to the task instance.
3. Notice and respond to the cancellation request in your user delegate.
4. Optionally notice on the calling thread that the task was canceled.

What happens if a task throws an exception?

When exception are thrown in a code that runs inside a task, all the exceptions are placed on the task object and returned to the calling thread. When exceptions happen, all the exceptions are re-thrown by the calling thread.

How does C# CancellationToken work?

A CancellationToken enables cooperative cancellation between threads, thread pool work items, or Task objects. You create a cancellation token by instantiating a CancellationTokenSource object, which manages cancellation tokens retrieved from its CancellationTokenSource. Token property.

What is cancellation token source?

A CancellationTokenSource object, which provides a cancellation token through its Token property and sends a cancellation message by calling its Cancel or CancelAfter method. A CancellationToken object, which indicates whether cancellation is requested.

How do you throw a task exception?

Throw Exception inside a Task – “await” vs Wait() static async void Main(string[] args) { Task t = new Task(() => { throw new Exception(); }); try { t. Start(); t. Wait(); } catch (AggregateException e) { // When waiting on the task, an AggregateException is thrown. }

How to avoid an exception when cancelling a task?

Also, Task.Wait (CancellationToken) will throw an exception if the token was cancelled. To use this method, you will need to wrap your Wait call in a Try…Catch block. I am trying to avoid any exceptions when cancelling.

Which is an example of a task cancellation?

The following example shows the basic pattern for task cancellation that throws the exception. Note that the token is passed to the user delegate and to the task instance itself.

What does it mean to cancel a task in MSDN?

Task Cancellation. If you are waiting on a Task that transitions to the Canceled state, a System.Threading.Tasks.TaskCanceledException exception (wrapped in an AggregateException exception) is thrown. Note that this exception indicates successful cancellation instead of a faulty situation.

When to throw an operationcanceledexception in task?

When user code in a task responds to a cancellation request, the correct procedure is to throw an OperationCanceledException passing in the cancellation token on which the request was communicated.