[3.10] gh-90622: Do not spawn ProcessPool workers on demand via fork method. (GH-91598) (GH-92497) (#92499)
Do not spawn ProcessPool workers on demand when they spawn via fork.
This avoids potential deadlocks in the child processes due to forking from
a multithreaded process..
(cherry picked from commit
ebb37fc3fdcb03db4e206db017eeef7aaffbae84)
Co-authored-by: Gregory P. Smith <greg@krypto.org>
(cherry picked from commit
b795376a628ae7cc354addbb926d724ebe364fec)
Co-authored-by: Gregory P. Smith <greg@krypto.org>
Co-authored-by: Gregory P. Smith <greg@krypto.org>