Skip to content

gh-135335: flush stdout/stderr in forkserver after preloading modules #135338

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 15 commits into from
Jun 18, 2025
Merged

gh-135335: flush stdout/stderr in forkserver after preloading modules #135338

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
15 commits
Select commit Hold shift + click to select a range
d59b229
gh-135335: flush stdout/stderr in forkserver after preloading modules
duaneg Jun 10, 2025
552266f
Attempt to fix MacOS test failures
duaneg Jun 10, 2025
6e36eea
Check stderr first to get details of assertion failures
duaneg Jun 10, 2025
33f9956
Further minor diagnostic improvements upon test failure
duaneg Jun 12, 2025
9944968
Set start method explicitly to "forkserver" so it works on MacOS (and…
duaneg Jun 16, 2025
1523e74
Address reviewer feedback: introduce some intermediate variables and …
duaneg Jun 17, 2025
2125574
Update Lib/test/_test_multiprocessing.py
duaneg Jun 17, 2025
db298cb
Additional review feedback: add comment and align ordering
duaneg Jun 17, 2025
f9bab0a
Update Lib/test/mp_preload_flush.py
duaneg Jun 17, 2025
4ffa138
Show default diff on unexpected stdout/err
duaneg Jun 17, 2025
4d57d74
Update Lib/test/_test_multiprocessing.py
duaneg Jun 17, 2025
e73ea34
Update Misc/NEWS.d/next/Library/2025-06-10-21-42-04.gh-issue-135335.W…
duaneg Jun 17, 2025
3f07ff7
Remove redundant check
duaneg Jun 17, 2025
da4df44
Don't write an newline to avoid any implicit flushes that might happen
duaneg Jun 18, 2025
fdb30e1
Be consistent and do not rely on asserts being enabled
duaneg Jun 18, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
Prev Previous commit
Next Next commit
Set start method explicitly to "forkserver" so it works on MacOS (and… 
… if the

defaults change elsewhere in the future)
  • Loading branch information
@duaneg
duaneg committed Jun 16, 2025
commit 9944968baede34b265d2dd0bbed39e4471e90c34
2 changes: 1 addition & 1 deletion Lib/test/_test_multiprocessing.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6815,7 +6815,7 @@ def test_std_streams_flushed_after_preload(self):
f.write('''if 1:
import sys
print('stdout', file=sys.stdout)
print('stderr', file=sys.stderr)''')
print('stderr', file=sys.stderr)\n''')

name = os.path.join(os.path.dirname(__file__), 'mp_preload_flush.py')
env = {'PYTHONPATH': self._temp_dir}
Expand Down
1 change: 1 addition & 0 deletions Lib/test/mp_preload_flush.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@

if __name__ == '__main__':
assert 'a' not in sys.modules
multiprocessing.set_start_method('forkserver')
multiprocessing.set_forkserver_preload(['a'])
for _ in range(2):
p = multiprocessing.Process()
Expand Down
Loading