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Created on 2021-02-06 05:50 by sanchit, last changed 2022-04-11 14:59 by admin.
| Pull Requests | |||
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| URL | Status | Linked | Edit |
| PR 24461 | open | sanchit, 2021-02-06 05:54 | |
| Messages (4) | |||
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| msg386546 - (view) | Author: Sanchit (sanchit) * | Date: 2021-02-06 05:50 | |
While spawning, if a process having code built on top of Python's multiprocessing module calls multiprocessing.reduction.DupFd() (in /Lib/multiprocessing/reduction.py) multiple times on the same File descriptor by mistake, then it ends up invoking duplicate_for_child(fd)) of the class Popen, which, in turn, adds a duplicate FD to a list. This list is then used in spawnv_passfds() in /Lib/multiprocessing/util.py, which uses that list as an argument in a call of _posixsubprocess.fork_exec(). In Modules/_posixsubprocess.c, checks exist to ensure that all the FDs in the list are unique, positive, and in a sorted order. If duplicate entries are found, a ValueError: bad value(s) in fds_to_keep exception is raised, and the execution is terminated. Even if this exception were somehow handled, a developer can't change the aforementioned FD list in Python without breaking modularity. It's better to let developers get away with calling multiprocessing.reduction.DupFd() (in /Lib/multiprocessing/reduction.py) on by not accepting duplicate entries in the first place, so that spawning a process can be successful. |
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| msg386881 - (view) | Author: Terry J. Reedy (terry.reedy) *  |
Date: 2021-02-12 21:43 | |
3.7 and before only get security fixes. |
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| msg386897 - (view) | Author: Sanchit (sanchit) * | Date: 2021-02-13 01:52 | |
But can you please add this fix in versions 3.8 & beyond? Thanks! ________________________________ From: report=bugs.python.org@roundup.psfhosted.org <report=bugs.python.org@roundup.psfhosted.org> on behalf of Terry J. Reedy <report@bugs.python.org> Sent: Friday, February 12, 2021 3:43 PM To: SANCHIT JAIN <sanchit@cs.wisc.edu> Subject: [issue43142] Do not add duplicate FDs to list in duplicate_for_child() Terry J. Reedy <tjreedy@udel.edu> added the comment: 3.7 and before only get security fixes. ---------- nosy: +davin, pitrou, terry.reedy versions: -Python 3.6, Python 3.7 _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue43142> _______________________________________ |
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| msg386913 - (view) | Author: Terry J. Reedy (terry.reedy) * |
Date: 2021-02-13 05:57 | |
I can't (lacking multiprocessing knowledge), but someone else might. PS: when replying via email, please delete post you are responding to. When added to the web page, the copy is redundant noise. |
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| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2022-04-11 14:59:41 | admin | set | github: 87308 |
| 2021-02-13 05:57:18 | terry.reedy | set | messages: + msg386913 |
| 2021-02-13 01:52:04 | sanchit | set | messages: + msg386897 |
| 2021-02-12 21:43:22 | terry.reedy | set | nosy:
+ terry.reedy, pitrou, davin messages: + msg386881 versions: - Python 3.6, Python 3.7 |
| 2021-02-06 05:54:24 | sanchit | set | keywords:
+ patch stage: patch review pull_requests: + pull_request23257 |
| 2021-02-06 05:50:31 | sanchit | create | |