Possible race condition in SubprocessFactory.finished()

[larsrc-google]

Description of the problem / feature request:

In SubprocessFactory.finished(), there's a check for exceeding the deadline, which may call process.destroy(). process.destroy() might not destroy the process, or process.isAlive() might return true for a bit longer.

Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

I haven't yet tried reproducing.

What operating system are you running Bazel on?

This potentially applies to all non-Windows OSes, but depends a lot on how process.destroy() actually works.

What's the output of bazel info release?

Code has been there since 0.14.0 (d3de5cc)

If bazel info release returns "development version" or "(@Non-Git)", tell us how you built Bazel.

N/A

What's the output of git remote get-url origin ; git rev-parse master ; git rev-parse HEAD ?

N/A

Have you found anything relevant by searching the web?

#6860 is somewhat related.

Any other information, logs, or outputs that you want to share?

Probably need to do a waitFor() to prevent the race.
It's unclear if this actually affects anything, philwo@ probably knows best.

[github-actions]

Thank you for contributing to the Bazel repository! This issue has been marked as stale since it has not had any activity in the last 2+ years. It will be closed in the next 14 days unless any other activity occurs or one of the following labels is added: "not stale", "awaiting-bazeler". Please reach out to the triage team (@bazelbuild/triage) if you think this issue is still relevant or you are interested in getting the issue resolved.

[larsrc-google]

Still the case, still not obvious if it affects anything in practice. Closing until we get some indication that it is an issue.