gh-127282: fix concurrent/future/thread.py: _python_exit

[GoodenoughPhysicsLab]

relate to #127282

• Issue: concurrent.future.thread._python_exit: continuing blocking while exceptions occureded on windows. #127282

[cpython-cla-bot]

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[ZeroIntensity]

Thanks for contributing! This needs a NEWS entry and a simple test (you'll probably need to add one to test_thread_pool).

I'm a little on the fence about this change, the timeout=2 feels a bit arbitrary, and I don't know how stable it is (this doesn't do anything for Linux, FWIW).

[GoodenoughPhysicsLab]

should we use platforms.system(), and even fix join further

[GoodenoughPhysicsLab]

it seems that there is no need to add a new dependence of platforms, I will have a try to add one to test.

[GoodenoughPhysicsLab]

it's hard for me to add a test, because the program can't know that he is blocked.

[GoodenoughPhysicsLab]

The problem of Thread.join have been fixed somewhere. Therefore, I'll close this issue.