shutil.make_archive should not need to chdir (alternatively: make shutil.make_archive thread-safe)

[AlexGaynor]

BPO	30511
Nosy	@tarekziade, @ambv, @serhiy-storchaka, @miss-islington, @michael-o, @FFY00, @akulakov
PRs	bpo-30511: Add note on thread safety to shutil.make_archive() #26933 [3.10] bpo-30511: Add note on thread safety to shutil.make_archive() (GH-26933) #27274 [3.9] bpo-30511: Add note on thread safety to shutil.make_archive() (GH-26933) #27275 [3.8] bpo-30511: Add note on thread safety to shutil.make_archive() (GH-26933) #27276 bpo-25625: add contextlib.chdir #28271

^{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 = None
created_at = <Date 2017-05-30.13:46:18.840>
labels = ['3.7', 'library']
title = 'shutil.make_archive should not need to chdir (alternatively: make shutil.make_archive thread-safe)'
updated_at = <Date 2021-09-17.13:26:13.713>
user = 'https://bugs.python.org/AlexGaynor'

bugs.python.org fields:

activity = <Date 2021-09-17.13:26:13.713>
actor = 'FFY00'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2017-05-30.13:46:18.840>
creator = 'Alex Gaynor'
dependencies = []
files = []
hgrepos = []
issue_num = 30511
keywords = ['patch']
message_count = 10.0
messages = ['294756', '294758', '294759', '294760', '297902', '389849', '396633', '397928', '397932', '397934', '397935']
nosy_count = 9.0
nosy_names = ['tarek', 'lukasz.langa', 'serhiy.storchaka', 'Alex Gaynor', 'Joey Harrington', 'miss-islington', 'michael-o', 'FFY00', 'andrei.avk']
pr_nums = ['26933', '27274', '27275', '27276', '28271']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = None
url = 'https://bugs.python.org/issue30511'
versions = ['Python 2.7', 'Python 3.7']

[AlexGaynor]

Currently shutil.make_archive uses os.chdir, however there's no need for that. Everything that's done could be equally accomplished with path manipulation:

https://github.com/python/cpython/blob/master/Lib/shutil.py#L773-L779

We should switch to using path manipulation in order to make shutil.make_archive thread safe.

(Flag: This is probably a good bug for someone with Python skills interested in contributing to CPython!)

[serhiy-storchaka]

Unfortunately this is not possible. The signature of functions registered with register_archive_format() doesn't support this.

[AlexGaynor]

None of those functions are a public API, so changing them shouldn't be a problem IMO.

[AlexGaynor]

Ugh, except via |register_archive_format|. |register_archive_format| could wrap callables passed to it to maintain the current behavior.

[JoeyHarrington]

It would be nice if there was at least a warning in the docs that make_archive is not thread-safe, and that if you have two threads creating archives that it's extremely likely you'll get erroneous results since the race condition lasts for the entire duration of the archive creation.

[michael-o]

Just wasted two hours for this. Can someone really update the documentation of it if this is not going to change.

[akulakov]

PR is added here:
#26933

[ambv]

New changeset 64f54b7 by andrei kulakov in branch 'main':
bpo-30511: Add note on thread safety to shutil.make_archive() (bpo-26933)
64f54b7

[ambv]

New changeset d17449f by Miss Islington (bot) in branch '3.10':
bpo-30511: Add note on thread safety to shutil.make_archive() (GH-26933) (GH-27274)
d17449f

[ambv]

New changeset c8e35ab by Miss Islington (bot) in branch '3.9':
bpo-30511: Add note on thread safety to shutil.make_archive() (GH-26933) (GH-27275)
c8e35ab

[ambv]

New changeset 54d3871 by Miss Islington (bot) in branch '3.8':
bpo-30511: Add note on thread safety to shutil.make_archive() (GH-26933) (bpo-27276)
54d3871