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GeezerVison is showing github.com — gh-146041: Avoid lock in sys.intern() for already interned strings by colesbury · Pull Request #146072 · python/cpython

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colesbury commented Mar 17, 2026 •

edited by bedevere-app Bot

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Fix free-threading scaling bottleneck in sys.intern and PyObject_SetAttr by avoiding the interpreter-wide lock when the string is already interned and immortalized.

Issue: Free threading scaling bottleneck in sys.intern() #146041

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          pythongh-146041: Avoid lock in sys.intern() for already interned strings

6142b58

colesbury added the topic-free-threading label

Mar 17, 2026

bedevere-app Bot mentioned this pull request

Mar 17, 2026

Free threading scaling bottleneck in sys.intern() #146041

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colesbury marked this pull request as ready for review

March 17, 2026 19:15

colesbury requested review from AA-Turner and ZeroIntensity as code owners

March 17, 2026 19:15

bedevere-app Bot added the awaiting core review label

Mar 17, 2026

colesbury requested review from encukou and mpage

March 17, 2026 19:15

colesbury commented Mar 17, 2026

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@encukou, please let me know if you'd like me to do this differently. I've removed the assertion about unicode state in _Py_SetImmortalUntracked. It was awkward to keep because this PR requires that interned state is set to SSTATE_INTERNED_IMMORTAL as the last step in interning for thread-safety.

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mpage approved these changes

Mar 17, 2026

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Looks correct to me

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Objects/unicodeobject.c

		PyObject *r;
		int res = PyDict_GetItemRef(interned, s, &r);
		if (res < 0) {
		PyErr_Clear();

mpage Mar 17, 2026

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Clearing the error here feels a little weird to me, but it's consistent with the rest of the function.

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bedevere-app Bot added awaiting merge and removed awaiting core review labels

Mar 17, 2026

colesbury added 3 commits

March 17, 2026 22:20


          Add scaling benchmark and fix refcount contention on type

4f977e0


          Any string for prefix is fine

5ba9f63


          Merge branch 'main' into pythongh-146041-intern-lock-free

6e59598

colesbury added 🔨 test-with-refleak-buildbots

Test PR w/ refleak buildbots; report in status section

needs backport to 3.14 bugs and security fixes labels

Mar 24, 2026

bedevere-bot commented Mar 24, 2026

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🤖 New build scheduled with the buildbot fleet by @colesbury for commit 6e59598 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F146072%2Fmerge

If you want to schedule another build, you need to add the 🔨 test-with-refleak-buildbots label again.

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bedevere-bot removed the 🔨 test-with-refleak-buildbots Test PR w/ refleak buildbots; report in status section label

Mar 24, 2026

colesbury merged commit 6009309 into python:main

Mar 24, 2026

98 of 103 checks passed

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miss-islington-app Bot commented Mar 24, 2026

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

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bedevere-app Bot removed the awaiting merge label

Mar 24, 2026

miss-islington-app Bot commented Mar 24, 2026

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Sorry, @colesbury, I could not cleanly backport this to 3.14 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker 60093096ba62110151d822b072a01061876e9404 3.14

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miss-islington-app Bot assigned colesbury

Mar 24, 2026

colesbury deleted the gh-146041-intern-lock-free branch

March 24, 2026 18:29

colesbury added a commit to colesbury/cpython that referenced this pull request

Mar 24, 2026


          [3.14] pythongh-146041: Avoid lock in sys.intern() for already intern…

7fa9a56

…ed strings (pythongh-146072)

Fix free-threading scaling bottleneck in sys.intern and `PyObject_SetAttr` by
avoiding the interpreter-wide lock when the string is already interned and
immortalized.
(cherry picked from commit 6009309)

Co-authored-by: Sam Gross <[email protected]>

bedevere-app Bot commented Mar 24, 2026

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GH-146390 is a backport of this pull request to the 3.14 branch.

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bedevere-app Bot removed the needs backport to 3.14 bugs and security fixes label

Mar 24, 2026

colesbury removed their assignment

Mar 24, 2026

colesbury added a commit that referenced this pull request

Mar 25, 2026


          [3.14] gh-146041: Avoid lock in sys.intern() for already interned str…

f2b5131

…ings (gh-146072) (#146390)

Fix free-threading scaling bottleneck in sys.intern and `PyObject_SetAttr` by
avoiding the interpreter-wide lock when the string is already interned and
immortalized.

(cherry picked from commit 6009309)

pablogsal mentioned this pull request

Apr 4, 2026

gh-130273: Fix traceback color output with unicode characters #142529

Merged

devdanzin mentioned this pull request

Apr 10, 2026

_Py_SetImmortal must be run on allocating thread (no-gil) #113956

Closed

clin1234 pushed a commit to clin1234/cpython that referenced this pull request

Apr 16, 2026


          pythongh-146041: Avoid lock in sys.intern() for already interned stri…

f6cc8f5

…ngs (pythongh-146072)

Fix free-threading scaling bottleneck in sys.intern and `PyObject_SetAttr` by
avoiding the interpreter-wide lock when the string is already interned and
immortalized.

ljfp pushed a commit to ljfp/cpython that referenced this pull request

Apr 25, 2026


          pythongh-146041: Avoid lock in sys.intern() for already interned stri…

9e07d04

…ngs (pythongh-146072)

Fix free-threading scaling bottleneck in sys.intern and `PyObject_SetAttr` by
avoiding the interpreter-wide lock when the string is already interned and
immortalized.

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mpage

mpage approved these changes

ZeroIntensity

Awaiting requested review from ZeroIntensity

ZeroIntensity is a code owner

AA-Turner

Awaiting requested review from AA-Turner

AA-Turner is a code owner

encukou

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colesbury commented Mar 17, 2026 • edited by bedevere-app Bot Loading Uh oh! There was an error while loading. Please reload this page.

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colesbury commented Mar 17, 2026 •

edited by bedevere-app Bot

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