gh-146197: Add Emscripten to CI by hoodmane · Pull Request #146198 · python/cpython

hoodmane · 2026-03-20T09:31:47Z

Time:

19m 28s without cache
17m 8s with cache

By comparison, the build bot took 32m 8s with cache. I guess the github action runners are quite a bit faster than the instance running the build bot.

Issue: Add CI job for Emscripten #146197

webknjaz

Looks great at glance! Does it need an entire hour to complete though? If not, I'd make the timeout smaller.

hoodmane · 2026-03-20T09:38:37Z

I just copied the timeout-minutes: 60 from reusable-wasi which doesn't need 60 minutes either.

hoodmane · 2026-03-20T09:49:13Z

!buildbot emscripten

bedevere-bot · 2026-03-20T09:49:16Z

🤖 New build scheduled with the buildbot fleet by @hoodmane for commit 9da3ed3 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F146198%2Fmerge

The command will test the builders whose names match following regular expression: emscripten

The builders matched are:

WASM Emscripten PR

hoodmane · 2026-03-20T09:55:39Z

So it took 19m 28s with no cache. But the cache is not working yet.

hoodmane · 2026-03-20T10:00:49Z

!buildbot emscripten

bedevere-bot · 2026-03-20T10:00:52Z

🤖 New build scheduled with the buildbot fleet by @hoodmane for commit d77a339 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F146198%2Fmerge

The command will test the builders whose names match following regular expression: emscripten

The builders matched are:

WASM Emscripten PR

Tools/build/compute-changes.py

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

hoodmane · 2026-03-20T10:08:04Z

!buildbot Emscripten

bedevere-bot · 2026-03-20T10:08:07Z

🤖 New build scheduled with the buildbot fleet by @hoodmane for commit 4276a51 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F146198%2Fmerge

The command will test the builders whose names match following regular expression: Emscripten

The builders matched are:

WASM Emscripten PR

hoodmane · 2026-03-20T10:23:25Z

!buildbot Emscripten

bedevere-bot · 2026-03-20T10:23:29Z

🤖 New build scheduled with the buildbot fleet by @hoodmane for commit 4276a51 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F146198%2Fmerge

The command will test the builders whose names match following regular expression: Emscripten

The builders matched are:

WASM Emscripten PR

hoodmane · 2026-03-20T11:45:12Z

!buildbot emscripten

bedevere-bot · 2026-03-20T11:45:16Z

🤖 New build scheduled with the buildbot fleet by @hoodmane for commit 1520ee8 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F146198%2Fmerge

The command will test the builders whose names match following regular expression: emscripten

The builders matched are:

WASM Emscripten PR

hugovk · 2026-03-20T12:29:47Z

0:00:00 load avg: 0.10 Run 501 tests sequentially in a single process

Is it required to run sequentially?

Although it can help to have some sequential CI, and there's slower jobs than this one so it won't be the bottleneck.

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

hoodmane · 2026-03-20T13:03:49Z

Is it required to run sequentially?

We don't have any threads or process support so I think so.

hugovk

Thanks!

hoodmane · 2026-03-20T14:48:11Z

!buildbot emscripten

bedevere-bot · 2026-03-20T14:48:16Z

🤖 New build scheduled with the buildbot fleet by @hoodmane for commit 9d545d1 🤖

Results will be shown at:

https://buildbot.python.org/all/#/grid?branch=refs%2Fpull%2F146198%2Fmerge

The command will test the builders whose names match following regular expression: emscripten

The builders matched are:

WASM Emscripten PR

webknjaz · 2026-03-20T16:30:41Z

Alright, let's set the timeout to 25-30 minutes — this will help catch problems early. We just need to cover the cacheless run, plus have some margin for networking + minor flakiness. Otherwise, situations with something getting stuck for 40min+ would waste CI resources..

hoodmane · 2026-03-20T20:33:31Z

Well we have:

  1 job  with timeout-minutes: 30
  5 jobs with timeout-minutes: 5
  8 jobs with timeout-minutes: 10
 26 jobs with timeout-minutes: 60

Since most other CI jobs seem to have timeout-minutes: 60 I'd prefer to just keep the setting here as for the rest and then lowering these timeouts can be dealt with systematically as a separate issue.

freakboy3742

Changes to the build script make sense to me; I'll leave it to others to approve the CI configs, but they broadly look good to me. I'll leave it to @hugovk or @webknjaz to make the final call on timeouts; I agree that 60 minutes seems excessive, but it's also consistently excessive, which is a separate problem.

hugovk

Future PR to review all timeout-minutes welcome.

The main reason for the setting is to make sure if something gets stuck, it doesn't sit there for the full six hours.

They don't get stuck too often, and better to have more spare time available than have slow builds cancelled before they're finished.

miss-islington-app · 2026-03-23T14:34:57Z

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

miss-islington-app · 2026-03-23T14:34:59Z

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

cherry_picker c94048be025ad9d39cd9307db8f503039094df11 3.14

hugovk · 2026-03-23T14:35:21Z

@hoodmane Please could you check the backport? Thanks!

(cherry picked from commit c94048b) Co-authored-by: Hood Chatham <roberthoodchatham@gmail.com> Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

bedevere-app · 2026-03-23T14:42:00Z

GH-146331 is a backport of this pull request to the 3.14 branch.

hoodmane · 2026-03-23T14:47:18Z

@hugovk unfortunately the github action will be crashing on main because we were crossed up by a commit that broke Emscripten tests. Fixed by this:
#146330

webknjaz · 2026-03-23T14:48:59Z

FTR it's usually easier to set the right timeout as a part of the initial integration since the following runs will make use of cache and somebody handling this in the future would need to have privileges to wipe all the cache records to see the slow durations for each job.

hoodmane · 2026-03-23T14:50:24Z

Well that makes sense. Do you think 30 minutes makes sense here? That is about 50% higher than the worst run without cache. Or 40 minutes for 2x?

…8577 * 'main' of github.com:python/cpython: pythongh-146197: Run -m test.pythoninfo on the Emscripten CI (python#146332) pythongh-146325: Use `test.support.requires_fork` in test_fastpath_cache_cleared_in_forked_child (python#146330) pythongh-146197: Add Emscripten to CI (python#146198) pythongh-143387: Raise an exception instead of returning None when metadata file is missing. (python#146234) pythongh-108907: ctypes: Document _type_ codes (pythonGH-145837) pythongh-146175: Soft-deprecate outdated macros; convert internal usage (pythonGH-146178) pythongh-146056: Rework ref counting in treebuilder_handle_end() (python#146167) Add a warning about untrusted input to `configparser` docs (python#146276) pythongh-145264: Do not ignore excess Base64 data after the first padded quad (pythonGH-145267) pythongh-146308: Fix error handling issues in _remote_debugging module (python#146309) pythongh-146192: Add base32 support to binascii (pythonGH-146193) pythongh-135953: Properly obtain main thread identifier in Gecko Collector (python#146045) pythongh-143414: Implement unique reference tracking for JIT, optimize unpacking of such tuples (pythonGH-144300) pythongh-146261: Fix bug in `_Py_uop_sym_set_func_version` (pythonGH-146291) pythongh-145144: Add more tests for UserList, UserDict, etc (pythonGH-145145) pythongh-143959: Fix test_datetime if _datetime is unavailable (pythonGH-145248) pythongh-146245: Fix reference and buffer leaks via audit hook in socket module (pythonGH-146248) pythongh-140049: Colorize exception notes in `traceback.py` (python#140051) Update docs for pythongh-146056 (pythonGH-146213)

hoodmane requested review from AA-Turner, ezio-melotti, hugovk and webknjaz as code owners March 20, 2026 09:31

bedevere-app bot mentioned this pull request Mar 20, 2026

Add CI job for Emscripten #146197

Open

bedevere-app bot added the awaiting review label Mar 20, 2026

hoodmane added skip news OS-emscripten and removed awaiting review labels Mar 20, 2026

pythongh-146197: Add Emscripten to CI

9da3ed3

hoodmane force-pushed the emscripten-ci branch from 0fe20eb to 9da3ed3 Compare March 20, 2026 09:33

webknjaz approved these changes Mar 20, 2026

View reviewed changes

bedevere-app bot added the awaiting core review label Mar 20, 2026

Try to fix cache

d77a339

hugovk reviewed Mar 20, 2026

View reviewed changes

Tools/build/compute-changes.py Show resolved Hide resolved

Update Tools/build/compute-changes.py

4276a51

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

hoodmane added 2 commits March 20, 2026 11:30

Check that cache works

830188c

Move mpdec and libffi into a dependencies subtable

1520ee8

Update .github/workflows/reusable-emscripten.yml

4eff826

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

restore-key*s*

b40fbf9

hugovk approved these changes Mar 20, 2026

View reviewed changes

bedevere-app bot added awaiting merge and removed awaiting core review labels Mar 20, 2026

hoodmane added 2 commits March 20, 2026 15:09

Make libffi build also key on mpdec

54b1b12

Force deps-hash update

9d545d1

freakboy3742 approved these changes Mar 22, 2026

View reviewed changes

hugovk approved these changes Mar 23, 2026

View reviewed changes

hugovk merged commit c94048b into python:main Mar 23, 2026
60 checks passed

bedevere-app bot removed the awaiting merge label Mar 23, 2026

miss-islington-app bot assigned hugovk Mar 23, 2026

hoodmane deleted the emscripten-ci branch March 23, 2026 14:35

bedevere-app bot removed the needs backport to 3.14 bugs and security fixes label Mar 23, 2026

Uh oh!

Conversation

hoodmane commented Mar 20, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

webknjaz left a comment

Choose a reason for hiding this comment

Uh oh!

hoodmane commented Mar 20, 2026

Uh oh!

hoodmane commented Mar 20, 2026

Uh oh!

bedevere-bot commented Mar 20, 2026

Uh oh!

hoodmane commented Mar 20, 2026

Uh oh!

hoodmane commented Mar 20, 2026

Uh oh!

bedevere-bot commented Mar 20, 2026

Uh oh!

Uh oh!

hoodmane commented Mar 20, 2026

Uh oh!

bedevere-bot commented Mar 20, 2026

Uh oh!

hoodmane commented Mar 20, 2026

Uh oh!

bedevere-bot commented Mar 20, 2026

Uh oh!

hoodmane commented Mar 20, 2026

Uh oh!

bedevere-bot commented Mar 20, 2026

Uh oh!

hugovk commented Mar 20, 2026

Uh oh!

hoodmane commented Mar 20, 2026

Uh oh!

hugovk left a comment

Choose a reason for hiding this comment

Uh oh!

hoodmane commented Mar 20, 2026

Uh oh!

bedevere-bot commented Mar 20, 2026

Uh oh!

webknjaz commented Mar 20, 2026

Uh oh!

hoodmane commented Mar 20, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

freakboy3742 left a comment

Choose a reason for hiding this comment

Uh oh!

hugovk left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

miss-islington-app bot commented Mar 23, 2026

Uh oh!

miss-islington-app bot commented Mar 23, 2026

Uh oh!

hugovk commented Mar 23, 2026

Uh oh!

bedevere-app bot commented Mar 23, 2026

Uh oh!

hoodmane commented Mar 23, 2026

Uh oh!

webknjaz commented Mar 23, 2026

Uh oh!

hoodmane commented Mar 23, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants

hoodmane commented Mar 20, 2026 •

edited

Loading

hoodmane commented Mar 20, 2026 •

edited

Loading