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gh-145142: Make str.maketrans safe under free-threading - #145157

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colesbury merged 13 commits into
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VanshAgarwal24036:gh-145142-dict-next-critical-section
Feb 27, 2026
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gh-145142: Make str.maketrans safe under free-threading#145157
colesbury merged 13 commits into
python:mainfrom
VanshAgarwal24036:gh-145142-dict-next-critical-section

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@VanshAgarwal24036

@VanshAgarwal24036VanshAgarwal24036 commented Feb 23, 2026•
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Replace unsafe PyDict_Next iteration with snapshot iteration using PyDict_Items to avoid crashes when the input dict is mutated concurrently under free-threading.

Adds a regression test.

@bedevere-appbedevere-appBot mentioned this pull request Feb 23, 2026
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colesbury
colesbury reviewed Feb 23, 2026
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A few comments below

Comment threadLib/test/test_free_threading/test_maketrans_threading.py Outdated
Comment threadObjects/unicodeobject.c Outdated
Comment threadMisc/NEWS.d/next/Core_and_Builtins/2026-02-23-23-18-28.gh-issue-145142.T-XbVe.rst Outdated
Comment threadLib/test/test_free_threading/test_maketrans_threading.py Outdated
picnixz
picnixz requested changes Feb 24, 2026
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I would suggest isolating the loop in a separate function so that we do not have those weird labels jumps and confusing names but this should be benchmarked on PGO/LTO tocheck that we do not introduce an overhead (though I am not that worried as str.maketrans() is usually not a hot function).

Comment threadObjects/unicodeobject.c Outdated
Comment threadObjects/unicodeobject.c Outdated
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bedevere-appBot commented Feb 24, 2026

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A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

sharktide
sharktide reviewed Feb 24, 2026
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Bunch of syntax errors you need to fix as well.

I also agree with picnixz’s comments

@VanshAgarwal24036
VanshAgarwal24036 marked this pull request as draft February 24, 2026 12:44
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VanshAgarwal24036force-pushed the gh-145142-dict-next-critical-section branch from d487864 to 05ba3f3CompareFebruary 24, 2026 15:57
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VanshAgarwal24036 marked this pull request as ready for review February 24, 2026 16:37
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VanshAgarwal24036force-pushed the gh-145142-dict-next-critical-section branch from 206f6b2 to 4e715b0CompareFebruary 24, 2026 17:34
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VanshAgarwal24036 commented Feb 24, 2026

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I have made the requested changes; please review again.

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Thanks for making the requested changes!

@picnixz: please review the changes made to this pull request.

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bedevere-appBot requested a review from picnixzFebruary 24, 2026 17:41
colesbury
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Comment threadObjects/unicodeobject.c Outdated
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LGTM, thanks

@colesburycolesbury added the needs backport to 3.14 bugs and security fixes label Feb 27, 2026
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colesbury enabled auto-merge (squash) February 27, 2026 15:41
eendebakpt
eendebakpt reviewed Feb 27, 2026
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Comment threadObjects/unicodeobject.c
}

static int
unicode_maketrans_from_dict(PyObject *x, PyObject *newdict)

@eendebakpteendebakptFeb 27, 2026

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Suggested change
unicode_maketrans_from_dict(PyObject*x, PyObject*newdict)
unicode_maketrans_from_dict_lock_held(PyObject*x, PyObject*newdict)

Naming convention for methods that require locking.

@colesbury
colesbury merged commit a249795 into python:mainFeb 27, 2026
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miss-islington-appBot commented Feb 27, 2026

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Thanks @VanshAgarwal24036 for the PR, and @colesbury for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14.
🐍🍒⛏🤖

miss-islington pushed a commit to miss-islington/cpython that referenced this pull request Feb 27, 2026
@VanshAgarwal24036@miss-islington
pythongh-145142: Make str.maketrans safe under free-threading (python…
0efb6a2
…gh-145157)
(cherry picked from commit a249795)
Co-authored-by: VanshAgarwal24036 <148854295+VanshAgarwal24036@users.noreply.github.com>
@bedevere-app

bedevere-appBot commented Feb 27, 2026

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GH-145320 is a backport of this pull request to the 3.14 branch.

@bedevere-appbedevere-appBot removed the needs backport to 3.14 bugs and security fixes label Feb 27, 2026
colesbury pushed a commit that referenced this pull request Feb 27, 2026
@miss-islington@VanshAgarwal24036
[3.14]gh-145142: Make str.maketrans safe under free-threading (gh-14…
d76c56e
…5157) (#145320)
Co-authored-by: VanshAgarwal24036 <148854295+VanshAgarwal24036@users.noreply.github.com>
@VanshAgarwal24036
VanshAgarwal24036 deleted the gh-145142-dict-next-critical-section branch February 27, 2026 16:42
brijkapadia pushed a commit to brijkapadia/cpython that referenced this pull request Feb 28, 2026
@VanshAgarwal24036@brijkapadia
pythongh-145142: Make str.maketrans safe under free-threading (python…
bbcb932
…gh-145157)
ljfp pushed a commit to ljfp/cpython that referenced this pull request Apr 25, 2026
@VanshAgarwal24036@ljfp
pythongh-145142: Make str.maketrans safe under free-threading (python…
1f6c471
…gh-145157)
@naschemenascheme mentioned this pull request Jul 14, 2026
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@eendebakpteendebakpteendebakpt left review comments
@colesburycolesburycolesbury approved these changes
@picnixzpicnixzpicnixz approved these changes
@sharktidesharktideAwaiting requested review from sharktide

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