Add an asyncio.TaskGroup.cancel method · Issue #108951 · python/cpython (original) (raw)

Feature or enhancement

Proposal:

Trio/anyio have a way to cancel all tasks within a taskgroup, via taskgroup.cancel_scope.cancel().

Asyncio doesn't have cancel scopes. The way to currently do this is to cancel the task which the taskgroup is a child of, but there are problems with this approach:

• the task is a private member of the taskgroup, so the task is inaccessible through it
• what about nested taskgroups?
• also passing the task around is additional overhead and risks cancelling it when the taskgroup is no longer active

To fix this, I propose to add a taskgroup.cancelmethod which behaves like task.cancel if the taskgroup is still active (i.e. not aborting).

If this change is likely to be accepted I'm OK with writing a PR.

Has this already been discussed elsewhere?

I have already discussed this feature proposal on Discourse

Links to previous discussion of this feature:

https://discuss.python.org/t/how-to-cancel-all-tasks-created-within-same-taskgroup/30215

Linked PRs

• gh-108951: document how to terminate an asyncio.TaskGroup #123837
• [3.13] gh-108951: Document how to terminate an asyncio.TaskGroup (GH-123837) #123956
• [3.12] gh-108951: Document how to terminate an asyncio.TaskGroup (GH-123837) #123957
• gh-108951: add TaskGroup.cancel() #127214