8000 gh-94972: document that shield users need to keep a reference to their task by graingert · Pull Request #94973 · python/cpython · GitHub
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gh-94972: document that shield users need to keep a reference to their task #94973

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gh-94972: document that shield users need to keep a reference to their task #94973

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c0f34a6
gh-94972: document that shield users need to keep a reference to thei…
graingert Jul 18, 2022
b16416f
fix garbage-collected typo - the correct spelling is garbage collected
graingert Jul 19, 2022
951b85a
Merge branch 'main' into shield
graingert Jul 19, 2022
8ffb38c
correct mid execution typo, the correct spelling is mid-execution
graingert Jul 19, 2022
0868b77
Merge branch 'main' into shield
graingert Aug 24, 2022
2c2e396
Apply suggestions from code review
graingert Aug 24, 2022
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2 changes: 1 addition & 1 deletion Doc/library/asyncio-future.rst
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Expand Up @@ -55,7 +55,7 @@ Future Functions
preferred way for creating new Tasks.

Save a reference to the result of this function, to avoid
a task disappearing mid execution.
a task disappearing mid-execution.

.. versionchanged:: 3.5.1
The function accepts any :term:`awaitable` object.
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17 changes: 13 additions & 4 deletions Doc/library/asyncio-task.rst
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Expand Up @@ -254,9 +254,9 @@ Creating Tasks
.. important::

Save a reference to the result of this function, to avoid
a task disappearing mid execution. The event loop only keeps
a task disappearing mid-execution. The event loop only keeps
weak references to tasks. A task that isn't referenced elsewhere
may get garbage-collected at any time, even before it's done.
may get garbage collected at any time, even before it's done.
For reliable "fire-and-forget" background tasks, gather them in
a collection::

Expand Down Expand Up @@ -520,7 +520,8 @@ Shielding From Cancellation

The statement::

res = await shield(something())
task = asyncio.create_task(something())
res = await shield(task)

is equivalent to::

Expand All @@ -539,11 +540,19 @@ Shielding From Cancellation
the ``shield()`` function should be combined with a try/except
clause, as follows::

task = asyncio.create_task(something())
try:
res = await shield(something())
res = await shield(task)
except CancelledError:
res = None

.. important::

Save a reference to tasks passed to this function, to avoid
a task disappearing mid-execution. The event loop only keeps
weak references to tasks. A task that isn't referenced elsewhere
may get garbage collected at any time, even before it's done.

.. versionchanged:: 3.10
Removed the *loop* parameter.

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