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gh-108951: document addition of TaskGroup.cancel()#149031

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belm0:taskgroup_cancel_docs
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gh-108951: document addition of TaskGroup.cancel()#149031
belm0 wants to merge 5 commits intopython:mainfrom
belm0:taskgroup_cancel_docs

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@belm0 belm0 commented Apr 26, 2026

@@ -1 +1 @@
Add :meth:`~asyncio.TaskGroup.cancel` which cancels unfinished tasks and exits the group without error.
Add :meth:`~asyncio.TaskGroup.cancel` which cancels unfinished tasks and exits the group without raising :exc:`asyncio.CancelledError`.
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I'm still not sure if the explicit "and exits the group without raising :exc:asyncio.CancelledError" makes sense. All this does is 1) cancel all current tasks in the group and 2) set the task group into aborted mode which causes creation of further tasks to fail. With that in mind, I'm not sure why you chose to explicitly mention exiting the task group.

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@agronholm agronholm Apr 26, 2026

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Further, this still begs to question why you said "without raising :exc:asyncio.CancelledError". This implies that otherwise it would raise a CancelledError, yes?

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@belm0 belm0 Apr 27, 2026

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well, if you check the long discussions in the impl PR, there was quite a bit made about possible confusion from expecting TaskGroup.cancel() to behave like Task.cancel(). So this is being explicit that unlike the latter, TaskGroup.cancel() does not cause anything to raise CancelledError.

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I think this could be reworded:

Add :meth:~asyncio.TaskGroup.cancel which cancels unfinished tasks in the group and prevents new ones from being created. If this requires cancellation of the host task, the task group will swallow the :exc:asyncio.CancelledError, unless the task was also cancelled from elsewhere.

Thoughts?

Comment thread Doc/whatsnew/3.15.rst Outdated
Co-authored-by: Alex Grönholm <alex.gronholm@nextday.fi>
Comment thread Doc/whatsnew/3.15.rst
@picnixz picnixz changed the title gh-108951: Whatsnew and doc tweaks for TaskGroup.cancel() gh-108951: document addition of TaskGroup.cancel() Apr 27, 2026
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LG, just one suggestion.

Comment thread Doc/whatsnew/3.15.rst Outdated
Comment thread Misc/NEWS.d/next/Library/2024-11-24-07-18-40.gh-issue-108951.jyKygP.rst Outdated
Comment thread Doc/whatsnew/3.15.rst Outdated
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picnixz commented Apr 28, 2026

I've updated the rST markup because otherwise it will only show "cancel()" as a link and the user won't know whether it's asyncio.cancel or asyncio.something.cancel(). Apart from the rewording of the NEWS entry that I have no strong opinion about, I think we can merge this.

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