If I understood correctly, Python 3.8 and 3.9 binaries provided by python.org is *not* impacted by this issue.

Only Python binaries built manually with explicit support for macOS 10.4 ("MAC_OS_X_VERSION_MIN_REQUIRED") were impacted.

Python 3.9 and older are not fixed (keep the lock). The workaround is to require macOS 10.5 or newer. macOS 10.4 was released in 2004, it's maybe time to stop support it :-)

Python 3.7 (and newer) requires macOS 10.6 or newer (again, I'm talking about binaries provided by python.org).


> bpo-25920: Remove socket.getaddrinfo() lock on macOS (GH-20177)

I chose to leave the lock for gethostbyname(). Ronald wrote that this lock is no longer needed:
"As an aside (not to be addressed in the PR): Apparently gethostbyname() and related functions are thread-safe on macOS. This is according to the manpage on macOS 10.15. I haven't checked in which version that changed. This allows avoiding the use of the gethostbyname lock as well."
https://github.com/python/cpython/pull/20177#pullrequestreview-418909595

Please open a separated issue for this lock.