diff options
Diffstat (limited to 'Misc/NEWS.d/next/Library/2024-04-04-15-28-12.gh-issue-116720.aGhXns.rst')
| -rw-r--r-- | Misc/NEWS.d/next/Library/2024-04-04-15-28-12.gh-issue-116720.aGhXns.rst | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/Misc/NEWS.d/next/Library/2024-04-04-15-28-12.gh-issue-116720.aGhXns.rst b/Misc/NEWS.d/next/Library/2024-04-04-15-28-12.gh-issue-116720.aGhXns.rst new file mode 100644 index 0000000..39c7d6b --- /dev/null +++ b/Misc/NEWS.d/next/Library/2024-04-04-15-28-12.gh-issue-116720.aGhXns.rst @@ -0,0 +1,18 @@ +Improved behavior of :class:`asyncio.TaskGroup` when an external cancellation +collides with an internal cancellation. For example, when two task groups +are nested and both experience an exception in a child task simultaneously, +it was possible that the outer task group would misbehave, because +its internal cancellation was swallowed by the inner task group. + +In the case where a task group is cancelled externally and also must +raise an :exc:`ExceptionGroup`, it will now call the parent task's +:meth:`~asyncio.Task.cancel` method. This ensures that a +:exc:`asyncio.CancelledError` will be raised at the next +:keyword:`await`, so the cancellation is not lost. + +An added benefit of these changes is that task groups now preserve the +cancellation count (:meth:`asyncio.Task.cancelling`). + +In order to handle some corner cases, :meth:`asyncio.Task.uncancel` may now +reset the undocumented ``_must_cancel`` flag when the cancellation count +reaches zero. |