X Tutup
Skip to content

Run subprocess-starting tests on separate runners#30278

Draft
jkseppan wants to merge 6 commits intomatplotlib:mainfrom
jkseppan:separate-subprocess-test-runners
Draft

Run subprocess-starting tests on separate runners#30278
jkseppan wants to merge 6 commits intomatplotlib:mainfrom
jkseppan:separate-subprocess-test-runners

Conversation

@jkseppan
Copy link
Copy Markdown
Member

@jkseppan jkseppan commented Jul 9, 2025

I suspect that we are running out of process IDs, or the scheduler
is not letting all subprocesses execute, leading to timeouts in
tests that start subprocesses when other long-running tests are
executing. This happens often with Python 3.14 tests for some reason.

Add a new pytest marker for the tests that start a subprocess at
top level, and run these tests in separate runners without
pytest-xdist parallelization.

I suspect that we are running out of process IDs, or the scheduler
is not letting all subprocesses execute, leading to timeouts in
tests that start subprocesses when other long-running tests are
executing. This happens often with Python 3.14 tests for some reason.

Add a new pytest marker for the tests that start a subprocess at
top level, and run these tests in separate runners without
pytest-xdist parallelization.
jkseppan added 5 commits July 9, 2025 11:10
- set PYTHONUNBUFFERED=1 to make the subprocess Python unbuffered
- set bufsize=0 making the parent process pipe unbuffered
- because that can return short reads, check if the subprocess
  exited, and if not, yield the CPU
- set stdin to DEVNULL and stderr to STDOUT to avoid blocking
  related to those
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Projects

None yet

Development

Successfully merging this pull request may close these issues.

1 participant

X Tutup