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Subprocess exceptions re-raised in parent process do not have child_traceback attribute #75631

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msekletar mannequin opened this issue Sep 13, 2017 · 4 comments
Closed

Subprocess exceptions re-raised in parent process do not have child_traceback attribute #75631

msekletar mannequin opened this issue Sep 13, 2017 · 4 comments
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3.7 (EOL) end of life stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error

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@msekletar
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Mannequin

msekletar mannequin commented Sep 13, 2017

BPO 31450
Nosy @gpshead, @tiran, @stratakis, @msekletar, @miss-islington
PRs
  • bpo-31450: Remove documentation mentioning that subprocess's child_tr… #11422
  • bpo-31450: Remove documentation mentioning that subprocess's child_tr… #11422
  • bpo-31450: Remove documentation mentioning that subprocess's child_tr… #11422
  • bpo-31450: Remove documentation mentioning that subprocess's child_tr… #11422
  • [3.7] bpo-31450: Remove documentation mentioning that subprocess's child_traceback is available with the parent process (GH-11422) #11426
  • [3.7] bpo-31450: Remove documentation mentioning that subprocess's child_traceback is available with the parent process (GH-11422) #11426
  • [3.7] bpo-31450: Remove documentation mentioning that subprocess's child_traceback is available with the parent process (GH-11422) #11426
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    Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

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    GitHub fields:

    assignee = None
closed_at = <Date 2019-01-07.15:43:57.994>
created_at = <Date 2017-09-13.12:25:50.310>
labels = ['3.7', 'type-bug', 'library']
title = 'Subprocess exceptions re-raised in parent process do not have child_traceback attribute'
updated_at = <Date 2019-01-07.15:43:57.994>
user = 'https://github.com/msekletar'

    bugs.python.org fields:

    activity = <Date 2019-01-07.15:43:57.994>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2019-01-07.15:43:57.994>
closer = 'vstinner'
components = ['Library (Lib)']
creation = <Date 2017-09-13.12:25:50.310>
creator = 'msekletar'
dependencies = []
files = []
hgrepos = []
issue_num = 31450
keywords = ['patch', 'patch', 'patch', 'patch']
message_count = 4.0
messages = ['302064', '302066', '332945', '332946']
nosy_count = 5.0
nosy_names = ['gregory.p.smith', 'christian.heimes', 'cstratak', 'msekletar', 'miss-islington']
pr_nums = ['11422', '11422', '11422', '11422', '11426', '11426', '11426']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue31450'
versions = ['Python 3.6', 'Python 3.7']
    @msekletar
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    msekletar mannequin commented Sep 13, 2017

    Issue
    -----
    Documentation of subprocess module claims that exceptions raised in child process will be re-raised in the parent process and will have child_traceback attribute set [1]. At least on Fedora Rawhide with python-3.6.2 this is not the case.

    Reproducer
    ----------

    $ cat preexec-exception.py
#!/usr/bin/env python3
    import subprocess

class PreExecCallback:
    def __call__(self):
        raise Exception()

if __name__ == "__main__":
    p = PreExecCallback()
    try:
    subprocess.Popen(['/bin/echo', 'foobar'], preexec_fn=p)
except subprocess.SubprocessError as e:
    if not hasattr(e, 'child_traceback'):
        print('BUG: Exception happened in child, but exception object does not have child_traceback attribute')

    Actual result
    -------------

    $ ./preexec-exception.py 
BUG: Exception happened in child, but exception object does not have child_traceback attribute

    Expected result
    ---------------
    No output, because child_traceback attribute is present

    Additional info
    ---------------
    I happened to notice this while working with pre-exec callbacks. However, according to https://stackoverflow.com/questions/38433837/subprocess-child-traceback this seems to be the generic problem.

    [1] https://docs.python.org/3/library/subprocess.html#exceptions

    @msekletar msekletar mannequin added stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error labels Sep 13, 2017
    @tiran
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    tiran commented Sep 13, 2017

    Documentation and implementation are out of sync. Python 3's subprocess module no longer sets child_traceback. I checked 3.3 to master. The assignment has been removed.

    @tiran tiran added the 3.7 (EOL) end of life label Sep 13, 2017
    @gpshead
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    gpshead commented Jan 3, 2019

    New changeset 47a2fce by Gregory P. Smith (Harmandeep Singh) in branch 'master':
    bpo-31450: Remove documentation mentioning that subprocess's child_traceback is available with the parent process (GH-11422)
    47a2fce

    @miss-islington
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    New changeset 47c035f by Miss Islington (bot) in branch '3.7':
    bpo-31450: Remove documentation mentioning that subprocess's child_traceback is available with the parent process (GH-11422)
    47c035f

    @vstinner vstinner closed this as completed Jan 7, 2019
    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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