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Created on 2022-03-20 14:58 by esoma, last changed 2022-04-11 14:59 by admin.
| Files | ||||
|---|---|---|---|---|
| File name | Uploaded | Description | Edit | |
| udpbug2.py | esoma, 2022-03-20 14:58 | |||
| windows_events.py | esoma, 2022-03-20 15:00 | |||
| Pull Requests | |||
|---|---|---|---|
| URL | Status | Linked | Edit |
| PR 32011 | open | esoma, 2022-03-20 15:48 | |
| Messages (4) | |||
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| msg415611 - (view) | Author: Erik Soma (esoma) * | Date: 2022-03-20 14:58 | |
Reproducer attached. Change `USE_PROACTOR` to `False` to use the `SelectorEventLoop` instead, which doesn't exhibit this behavior. The output on my machine when using the proactor loop is: ``` datagram received b'ping 1' datagram received b'ping 2' ``` And the selector loop (which is the behavior I would expect): ``` datagram received b'ping 1' datagram received b'ping 2' datagram received b'ping 3' ``` At a high level, after sending data to an address that isn't listening the asyncio protocol will no longer receive messages. Digging deeper, `_ProactorDatagramTransport._loop_reading` encounters the windows error 1234 (ERROR_PORT_UNREACHABLE) after the "bad send". It appears this a (undocumented/buggy?) behavior of `WSARecvFrom` where the next call to it after an unreachable `WSASendTo` in UDP mode will return the ICMP unreachable message. The actual error is returned from `GetOverlappedResult`. I've hacked together a fix that retries `IocpProactor.recvfrom` if the result is ERROR_PORT_UNREACHABLE. It fixes the issue for the reproducer and my actual use case, but it's probably not ideal. My solution for the moment is just to use the SelectorEventLoop instead. |
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| msg415612 - (view) | Author: Erik Soma (esoma) * | Date: 2022-03-20 15:00 | |
Uploading my hack to `asyncio.windows_events.py` -- this is based off 3.10.2's distribution. |
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| msg415614 - (view) | Author: Andrew Svetlov (asvetlov) *  |
Date: 2022-03-20 15:38 | |
Thanks for the report. Could you make a pull request? The whole attached windows_events.py is hard to analyze. |
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| msg415617 - (view) | Author: Erik Soma (esoma) * | Date: 2022-03-20 15:48 | |
Certainly: https://github.com/python/cpython/pull/32011 |
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| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2022-04-11 14:59:57 | admin | set | github: 91227 |
| 2022-03-20 15:48:54 | esoma | set | messages: + msg415617 |
| 2022-03-20 15:48:18 | esoma | set | keywords:
+ patch stage: patch review pull_requests: + pull_request30099 |
| 2022-03-20 15:38:09 | asvetlov | set | messages: + msg415614 |
| 2022-03-20 15:00:21 | esoma | set | files:
+ windows_events.py messages: + msg415612 |
| 2022-03-20 14:58:17 | esoma | create | |
