| msg362078 - (view) |
Author: Ben Darnell (Ben.Darnell) * |
Date: 2020-02-16 16:41 |
| Proactor and selector event loops behave differently when call_soon_threadsafe races with a concurrent call to loop.close(). In a selector event loop, call_soon_threadsafe will either succeed or raise a RuntimeError("Event loop is closed"). In a proactor event loop, it could raise this RuntimeError, but it can also raise an AttributeError due to an unguarded access to self._csock. https://github.com/python/cpython/blob/1ed61617a4a6632905ad6a0b440cd2cafb8b6414/Lib/asyncio/proactor_events.py#L785-L787 Comments in BaseSelectorEventLoop._write_to_self indicate that this is deliberate, so the `csock is not None` check here should probably be copied to the proactor event loop version. https://github.com/python/cpython/blob/1ed61617a4a6632905ad6a0b440cd2cafb8b6414/Lib/asyncio/selector_events.py#L129-L136 I'd also accept an answer that the exact behavior of this race is undefined and it's up to the application to either arrange for all calls to call_soon_threadsafe to stop before closing the loop. However, I've had users of Tornado argue that they use the equivalent of call_soon_threadsafe in contexts where this coordination would be difficult, and I've decided that tornado's version of this method would never raise, even if there is a concurrent close. So if asyncio declines to specify which exceptions are allowed in this case, tornado will need to add a blanket `except Exception:` around calls to call_soon_threadsafe. |
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| msg366793 - (view) |
Author: Łukasz Langa (lukasz.langa) *  |
Date: 2020-04-19 17:14 |
| Good catch. We should fix this for Python 3.8.3. |
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| msg366839 - (view) |
Author: Chris Meyer (cmeyer) * |
Date: 2020-04-20 15:06 |
| Is this related to bpo-39010 too? |
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| msg366840 - (view) |
Author: Ben Darnell (Ben.Darnell) * |
Date: 2020-04-20 15:10 |
| No, this is unrelated to bpo-39010. |
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| msg368791 - (view) |
Author: Łukasz Langa (lukasz.langa) * |
Date: 2020-05-13 17:25 |
| This sadly missed 3.8.3 but I want this addressed for 3.8.4. |
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| msg373594 - (view) |
Author: Łukasz Langa (lukasz.langa) * |
Date: 2020-07-13 11:36 |
| We have trouble finding a Windows expert with available time to address this :/ This is missing 3.8.4 as well. |
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| msg376784 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2020-09-12 06:50 |
| New changeset 1b0f0e3d7d03155da1cf9769a847874d559e57e3 by Victor Stinner in branch 'master': bpo-39651: Fix asyncio proactor _write_to_self() (GH-22197) https://github.com/python/cpython/commit/1b0f0e3d7d03155da1cf9769a847874d559e57e3 |
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| msg376785 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2020-09-12 06:53 |
| Thanks for the bug report Ben Darnell, it's now fixed. |
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| msg376790 - (view) |
Author: miss-islington (miss-islington) |
Date: 2020-09-12 07:10 |
| New changeset 530d1105ed7b0aa5ef76e3116918fe39bc6a4823 by Miss Islington (bot) in branch '3.8': bpo-39651: Fix asyncio proactor _write_to_self() (GH-22197) https://github.com/python/cpython/commit/530d1105ed7b0aa5ef76e3116918fe39bc6a4823 |
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| msg376791 - (view) |
Author: miss-islington (miss-islington) |
Date: 2020-09-12 07:11 |
| New changeset 7dfcc8e0795cce6a8cb42ae2a7f159a38da6b38a by Miss Islington (bot) in branch '3.9': bpo-39651: Fix asyncio proactor _write_to_self() (GH-22197) https://github.com/python/cpython/commit/7dfcc8e0795cce6a8cb42ae2a7f159a38da6b38a |
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