gh-135335: flush stdout/stderr in forkserver after preloading modules #135338
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…odules If a preloaded module writes to stdout or stderr, and the stream is buffered, child processes will inherit the buffered data after forking. Attempt to prevent this by flushing the streams after preload.
...or at least produce more useful output if they fail
efimov-mikhail
suggested changes
Jun 11, 2025
| p.start() | ||
| p.join() | ||
| else: | ||
| assert 'a' in sys.modules |
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There is a problem with this test, see
https://github.com/python/cpython/actions/runs/15558229444/job/43803979297?pr=135338
Each test should be written in such a way that make -j test command can be runned w/o errors.
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If a preloaded module writes to stdout or stderr, and the stream is buffered, child processes will inherit the buffered data after forking. Attempt to prevent this by flushing the streams after preload.