> My read is that as long as we're not confident enough to remove those checks from pytime.c, a caller should assume they're reachable. If the pytime checks need to stay, adding a Windows only pytime init check to make sure that locks won't deadlock sounds fine to me.

If you consider that the risk is non-zero, you can add a check at startup.

Do you expect that a startup check is enough, or do you expect failures later?

I understood that if the first call succeed, later calls are very unlikely to fail. The first call should be enough to check for all possible errors.