[core] Only one of the threads in a thread pool will be initialized as a long-running Python thread

[kevin85421]

What happened + What you expected to happen

Currently, only one of the threads in a thread pool will be initialized as a long-running Python thread. I should also investigate whether it's possible to call PyGILState_Release on a different thread other than the one calls PyGILState_Ensure in the thread pool.

Versions / Dependencies

TODO

Reproduction script

TODO

Issue Severity

None