gh-145098: Run Apple Silicon macOS CI on macos-26 (Tahoe) by clintonsteiner · Pull Request #145099 · python/cpython

clintonsteiner · 2026-02-22T07:26:52Z

Issue: CI: move Apple Silicon macOS workflows to macos-26 (Tahoe) #145098

hugovk

I'm curious if there's any performance difference between this and the previous one, can you compare times?

Also noting this image is still in beta but should be GA ~~"around November" [2025]~~, ~~"before Xcode 26.3 releases" [20 Feb]~~, "late February / early March, but depends on Xcode 26.4 behavior in general, so no promises".

actions/runner-images#13008

I don't see this as a blocker as long as everything we need is in there.

hugovk · 2026-02-22T10:18:06Z

Job	`macos-14` (main)	`macos-26` (PR)	Diff
build and test	8m 39s	12m 11s	+3m 32s (+41%)
free-threading build and test	15m 58s	18m 25s	+2m 27s (+15%)
Android (aarch64)	4m 09s	3m 34s	-35s (-14%)
iOS	16m 29s	21m 34s	+5m 05s (+31%)
JIT aarch64 (Debug)	15m 43s	15m 04s	-39s (-4%)
JIT aarch64 (Release)	15m 36s	13m 09s	-2m 27s (-16%)
tail-call aarch64	9m 54s	9m 45s	-9s (-2%)

webknjaz

Bumping the OS seems fine, although the downloader refactoring feels standalone..

freakboy3742 · 2026-02-22T21:57:42Z

My concern is less about speed, and more about reliability.

For background - there is no issue running CPython on macOS-26. This is entirely a GitHub Actions issue.

The macOS-15 runner has proven to be massively unreliable, and I haven't seen any movement on actions/runner-images#12777 or actions/runner-images#13275/actions/runner-images#13459 that suggests those issues have been fixed.

Before this lands, I'd want to see a dozen or so re-runs to give some confidence that the simulator boot reliability issues we've seen on macOS-15 have been resolved on macOS-26.

I also share the concern about conflating the downloading change with the CI change - is there a direct connection with the macOS runner here? The comment about "some runner/proxy setups" suggests it might be... but it's not clear if this is only to address an issue you've seen locally.

clintonsteiner · 2026-02-22T22:34:51Z

I changed the download run probably due to unreliability of the runner, failed downloads twice and didn't know if it was a regression in the os of the runner's curl capability @freakboy3742

freakboy3742 · 2026-02-22T22:59:20Z

I changed the download run probably due to unreliability of the runner, failed downloads twice and didn't know if it was a regression in the os of the runner's curl capability @freakboy3742

GitHub Actions failing downloads is a fairly common, but entirely inconsistent phenomenon. I've seen errors from GitHub accessing GitHub downloads. Unless you have concrete evidence that the issue is HTTP 1.1 compliance, I'd rather not complicate that section of code (or at least defer it to a separate PR, where we can address the same issue on other platforms like Android and Emscripten).

clintonsteiner · 2026-02-22T23:00:44Z

@freakboy3742 agreed, I had just pushed a revert a minute ago actually

hugovk · 2026-02-23T05:35:16Z

@clintonsteiner Please can you resolve the conflict in jit.yml?

And revert the unrelated changes to Include/internal/pycore_dict.h and Objects/dictobject.c?

27b3fa0

python-cla-bot · 2026-02-24T01:16:16Z

All commit authors signed the Contributor License Agreement.

clintonsteiner · 2026-02-24T01:17:22Z

@hugovk done, thank you!

savannahostrowski

LGTM for jit.yml but also in general!

freakboy3742

Broadly looks good; a couple of specific suggestions that might impact testing time. All evidence I've seen says there's a very restricted set of images that are pre-warmed, and that pre-warming is good for up to 10 minutes of test time.

I also want to see the iOS job pass a dozen times in succession before this is merged - historically, GitHub's iOS runners are very inconsistent, and I don't want to merge this only to have to revert it because it didn't trigger

hugovk · 2026-03-25T11:15:41Z

Thanks!

miss-islington-app · 2026-03-25T11:15:51Z

Thanks @clintonsteiner for the PR, and @hugovk for merging it 🌮🎉.. I'm working now to backport this PR to: 3.10, 3.11, 3.12, 3.13, 3.14.
🐍🍒⛏🤖

miss-islington-app · 2026-03-25T11:15:57Z

Sorry, @clintonsteiner and @hugovk, I could not cleanly backport this to 3.13 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker 4240c7dd7499c9024bae73a31fb25697203ae615 3.13

…onGH-145099) (cherry picked from commit 4240c7d) Co-authored-by: clintonsteiner <47841949+clintonsteiner@users.noreply.github.com>

miss-islington-app · 2026-03-25T11:16:01Z

Sorry, @clintonsteiner and @hugovk, I could not cleanly backport this to 3.12 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker 4240c7dd7499c9024bae73a31fb25697203ae615 3.12

bedevere-app · 2026-03-25T11:16:02Z

GH-146412 is a backport of this pull request to the 3.14 branch.

miss-islington-app · 2026-03-25T11:16:05Z

Sorry, @clintonsteiner and @hugovk, I could not cleanly backport this to 3.11 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker 4240c7dd7499c9024bae73a31fb25697203ae615 3.11

miss-islington-app · 2026-03-25T11:16:09Z

Sorry, @clintonsteiner and @hugovk, I could not cleanly backport this to 3.10 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker 4240c7dd7499c9024bae73a31fb25697203ae615 3.10

hugovk · 2026-03-25T11:18:28Z

I'll reapply the backport labels one-by-one on the oldest backport PR, there should be a smaller diff to fix each time.

…145099) (#146412) Co-authored-by: clintonsteiner <47841949+clintonsteiner@users.noreply.github.com>

… (Tahoe) (pythonGH-145099) (pythonGH-146412) (cherry picked from commit ce78904)

pythonGH-145099) (pythonGH-146412) (cherry picked from commit ce78904) Co-authored-by: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Co-authored-by: clintonsteiner <47841949+clintonsteiner@users.noreply.github.com>

…145099) (GH-146412) (#146414) Co-authored-by: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Co-authored-by: clintonsteiner <47841949+clintonsteiner@users.noreply.github.com>

pythonGH-145099) (pythonGH-146412) (pythonGH-146414) (cherry picked from commit 0dcb625) Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com> Co-authored-by: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Co-authored-by: clintonsteiner <47841949+clintonsteiner@users.noreply.github.com>

…145099) (GH-146412) (GH-146414) (#146635) Co-authored-by: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Co-authored-by: clintonsteiner <47841949+clintonsteiner@users.noreply.github.com>

…145099) (GH-146412) (GH-146414) (GH-146635) (#146638) Co-authored-by: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Co-authored-by: clintonsteiner <47841949+clintonsteiner@users.noreply.github.com>

PyFrozenDict_Type.tp_doc was set to `dictionary_doc`, which describes `dict()` — saying "dict() -> new empty dictionary" throughout. Since frozendict is a separate type, it needs its own docstring. Add a `frozendict_doc` with correct "frozendict()" references and a note that frozendict is immutable and hashable. https://claude.ai/code/session_01EdeU6enhg5YoLvKmBPpiZf

…on#145099)

clintonsteiner requested review from AA-Turner, ezio-melotti, hugovk and webknjaz as code owners February 22, 2026 07:26

bedevere-appBot mentioned this pull request Feb 22, 2026
CI: move Apple Silicon macOS workflows to macos-26 (Tahoe) #145098
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clintonsteiner requested a review from freakboy3742 as a code owner February 22, 2026 07:37

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hugovk merged commit 4240c7d into python:mainMar 25, 2026
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bedevere-appBot removed the awaiting merge label Mar 25, 2026

miss-islington-appBot assigned hugovk Mar 25, 2026

bedevere-appBot removed the needs backport to 3.14 bugs and security fixes label Mar 25, 2026

hugovk removed needs backport to 3.13 bugs and security fixes needs backport to 3.12 only security fixes needs backport to 3.11 only security fixes needs backport to 3.10 only security fixes labels Mar 25, 2026

hugovk pushed a commit that referenced this pull request Mar 25, 2026
[3.14]gh-145098: Run Apple Silicon macOS CI on macos-26 (Tahoe) (GH-…
ce78904
…145099) (#146412) Co-authored-by: clintonsteiner <47841949+clintonsteiner@users.noreply.github.com>

hugovk added a commit to hugovk/cpython that referenced this pull request Mar 25, 2026
fixup! [3.13]pythongh-145098: Run Apple Silicon macOS CI on macos-26…
c8a4883
… (Tahoe) (pythonGH-145099) (pythonGH-146412) (cherry picked from commit ce78904)

hugovk mentioned this pull request Apr 2, 2026
test_wm_iconbitmap() timeout after 10 min on "macOS / build and test (macos-26-intel)" CI #146531
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pablogsal mentioned this pull request Apr 4, 2026
gh-130273: Fix traceback color output with unicode characters #142529
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clin1234 pushed a commit to clin1234/cpython that referenced this pull request Apr 16, 2026
pythongh-145098: Run Apple Silicon macOS CI on macos-26 (Tahoe) (pyth…
5188fa3
…on#145099)

ljfp pushed a commit to ljfp/cpython that referenced this pull request Apr 25, 2026
pythongh-145098: Run Apple Silicon macOS CI on macos-26 (Tahoe) (pyth…
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…on#145099)

freakboy3742 mentioned this pull request Jul 13, 2026
gh-153631: Move to macos-26 runner for iOS #153632
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