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Created on 2021-12-30 17:12 by colesbury, last changed 2022-01-11 03:32 by corona10. This issue is now closed.
| Pull Requests | |||
|---|---|---|---|
| URL | Status | Linked | Edit |
| PR 30470 | merged | colesbury, 2022-01-07 22:09 | |
| PR 30523 | merged | miss-islington, 2022-01-11 03:03 | |
| PR 30524 | merged | miss-islington, 2022-01-11 03:03 | |
| Messages (5) | |||
|---|---|---|---|
| msg409374 - (view) | Author: Sam Gross (colesbury) *  |
Date: 2021-12-30 17:12 | |
The runtest_mp.py has a race condition between checking for worker.is_alive() and processing the queue that can lead to indefinite hangs. The hang happens when the all the results from the self.output queue are processed but at least one of the workers hasn't finished exiting. https://github.com/python/cpython/blob/8d7644fa64213207b8dc6f555cb8a02bfabeced2/Lib/test/libregrtest/runtest_mp.py#L394-L418 The main thread tries to get a result from the output queue, but the queue is empty and remains empty. Although the queue.get() operation eventually times out (after 30 seconds), the main thread does not re-check if all the workers have exited (!), but instead retries the queue.get() in the "while True" loop. https://github.com/python/cpython/blob/8d7644fa64213207b8dc6f555cb8a02bfabeced2/Lib/test/libregrtest/runtest_mp.py#L415-L418 To reproduce, apply the below patch which introduces a small delay to more reliably trigger the hang. curl "https://gist.githubusercontent.com/colesbury/fe3769f43dfb724c86ecbb182b1f6749/raw/e29a4eaeebb8d5252cdd66f3f8a70f7bc5fa14e7/runtest_mp.diff" | patch -p1 ./python -m test test_regrtest -m test_module_from_test_autotest -v |
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| msg409740 - (view) | Author: STINNER Victor (vstinner) *  |
Date: 2022-01-05 09:19 | |
Do you want to work on a fix? |
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| msg410271 - (view) | Author: Dong-hee Na (corona10) * |
Date: 2022-01-11 03:03 | |
New changeset e13cdca0f5224ec4e23bdd04bb3120506964bc8b by Sam Gross in branch 'main': bpo-46205: exit if no workers are alive in runtest_mp (GH-30470) https://github.com/python/cpython/commit/e13cdca0f5224ec4e23bdd04bb3120506964bc8b |
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| msg410272 - (view) | Author: miss-islington (miss-islington) | Date: 2022-01-11 03:29 | |
New changeset e0ec08dc49f8e6f94a735bc9946ef7a3fd898a44 by Miss Islington (bot) in branch '3.10': bpo-46205: exit if no workers are alive in runtest_mp (GH-30470) https://github.com/python/cpython/commit/e0ec08dc49f8e6f94a735bc9946ef7a3fd898a44 |
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| msg410273 - (view) | Author: miss-islington (miss-islington) | Date: 2022-01-11 03:32 | |
New changeset 690ed889c537c008a2c5f3e6c4f06c5b0c0afbc6 by Miss Islington (bot) in branch '3.9': bpo-46205: exit if no workers are alive in runtest_mp (GH-30470) https://github.com/python/cpython/commit/690ed889c537c008a2c5f3e6c4f06c5b0c0afbc6 |
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| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2022-01-11 03:32:45 | corona10 | set | status: open -> closed stage: patch review -> resolved |
| 2022-01-11 03:32:39 | corona10 | set | versions: - Python 3.8 |
| 2022-01-11 03:32:24 | miss-islington | set | messages: + msg410273 |
| 2022-01-11 03:29:39 | miss-islington | set | messages: + msg410272 |
| 2022-01-11 03:03:46 | corona10 | set | messages: + msg410271 |
| 2022-01-11 03:03:36 | miss-islington | set | pull_requests: + pull_request28725 |
| 2022-01-11 03:03:32 | miss-islington | set | nosy:
+ miss-islington pull_requests: + pull_request28724 |
| 2022-01-09 05:26:08 | corona10 | set | nosy:
+ corona10 |
| 2022-01-07 22:09:49 | colesbury | set | keywords:
+ patch stage: patch review pull_requests: + pull_request28673 |
| 2022-01-05 09:19:50 | vstinner | set | components:
+ Tests title: Race condition in runtest_mp leads to hangs (never exits) -> test.libregrtest: Race condition in runtest_mp leads to hangs (never exits) |
| 2022-01-05 09:19:38 | vstinner | set | messages: + msg409740 |
| 2021-12-30 17:17:54 | colesbury | set | nosy:
+ vstinner |
| 2021-12-30 17:13:13 | colesbury | set | type: behavior |
| 2021-12-30 17:12:53 | colesbury | create | |