bpo-34872: Fix self-cancellation in C implementation of asyncio.Task #9679
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The C implementation of asyncio.Task currently fails to perform the cancellation cleanup correctly in the following scenario. async def task1(): async def task2(): await task3 # task3 is never cancelled asyncio.current_task().cancel() await asyncio.create_task(task2()) The actuall error is a hardcoded call to `future_cancel()` instead of calling the `cancel()` method of a future-like object. Thanks to Vladimir Matveev for noticing the code discrepancy and to Yury Selivanov for coming up with a pathological scenario.
1st1 approved these changes Oct 2, 2018
asvetlov reviewed Oct 3, 2018
| PyObject *r; | ||
| r = future_cancel(fut); | ||
| int is_true; | ||
| r = _PyObject_CallMethodId(fut, &PyId_cancel, NULL); |
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The fix is correct.
But I'd like to go one step forward: use Future_CheckExact and Task_CheckExact to call future_cancel() and _asyncio_Task_cancel_impl() as fast paths.
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Id keep it as simple as possible as it needs to be backported to 3.6 & 3.7. A proper refactoring for C code is needed anyways, and I'll add this optimization.
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| Sorry, @elprans and @1st1, I could not cleanly backport this to |
Contributor
| Sorry, @elprans and @1st1, I could not cleanly backport this to |
Member
| @elprans please submit two PRs to backport the change to 3.7 and 3.6. The automatic cherry-picking has failed :( |
| GH-9690 is a backport of this pull request to the 3.6 branch. |
elprans added a commit to elprans/cpython that referenced this pull request Oct 3, 2018
….Task (pythonGH-9679) The C implementation of asyncio.Task currently fails to perform the cancellation cleanup correctly in the following scenario. async def task1(): async def task2(): await task3 # task3 is never cancelled asyncio.current_task().cancel() await asyncio.create_task(task2()) The actuall error is a hardcoded call to `future_cancel()` instead of calling the `cancel()` method of a future-like object. Thanks to Vladimir Matveev for noticing the code discrepancy and to Yury Selivanov for coming up with a pathological scenario. (cherry picked from commit 548ce9d)
| GH-9691 is a backport of this pull request to the 3.7 branch. |
elprans added a commit to elprans/cpython that referenced this pull request Oct 3, 2018
….Task (pythonGH-9679) The C implementation of asyncio.Task currently fails to perform the cancellation cleanup correctly in the following scenario. async def task1(): async def task2(): await task3 # task3 is never cancelled asyncio.current_task().cancel() await asyncio.create_task(task2()) The actuall error is a hardcoded call to `future_cancel()` instead of calling the `cancel()` method of a future-like object. Thanks to Vladimir Matveev for noticing the code discrepancy and to Yury Selivanov for coming up with a pathological scenario.. (cherry picked from commit 548ce9d) Co-authored-by: Elvis Pranskevichus <elvis@magic.io>
miss-islington pushed a commit that referenced this pull request Oct 3, 2018
….Task (GH-9679) (GH-9690) The C implementation of asyncio.Task currently fails to perform the cancellation cleanup correctly in the following scenario. async def task1(): async def task2(): await task3 # task3 is never cancelled asyncio.current_task().cancel() await asyncio.create_task(task2()) The actuall error is a hardcoded call to `future_cancel()` instead of calling the `cancel()` method of a future-like object. Thanks to Vladimir Matveev for noticing the code discrepancy and to Yury Selivanov for coming up with a pathological scenario. (cherry picked from commit 548ce9d) https://bugs.python.org/issue34872
miss-islington pushed a commit that referenced this pull request Oct 3, 2018
….Task (GH-9679) (GH-9691) The C implementation of asyncio.Task currently fails to perform the cancellation cleanup correctly in the following scenario. async def task1(): async def task2(): await task3 # task3 is never cancelled asyncio.current_task().cancel() await asyncio.create_task(task2()) The actuall error is a hardcoded call to `future_cancel()` instead of calling the `cancel()` method of a future-like object. Thanks to Vladimir Matveev for noticing the code discrepancy and to Yury Selivanov for coming up with a pathological scenario.. (cherry picked from commit 548ce9d) Co-authored-by: Elvis Pranskevichus <elvis@magic.io> https://bugs.python.org/issue34872
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The C implementation of asyncio.Task currently fails to perform the
cancellation cleanup correctly in the following scenario.
The actuall error is a hardcoded call to
future_cancel()instead ofcalling the
cancel()method of a future-like object.Thanks to Vladimir Matveev for noticing the code discrepancy and to
Yury Selivanov for coming up with a pathological scenario.
https://bugs.python.org/issue34872