> Victor, try to add importlib.invalidate_caches() inside a loop. Does it cause a failure in a single test_concurrency?

I added a "importlib.invalidate_caches()" call in the "for i in range(10):" loop. With this change, a single run doesn't fail. It doesn't fix the test neither: with -R 3:100, the command still fails.

> Some parts of import machinery are platform depended (see issue30873).

I don't think that this issue30873 or issue30626 is platform dependent.


> I don't have idea what is wrong on Windows.

IMHO it's just that my Windows VM is slow. It's a race condition. If I run "./python -m test -m test_concurrency test_import test_import": the command pass, but when again, it fails. It's pure random :-)