Specifically, with regard to PyEval_InitThreads(), it says:
The PyEval_InitThreads() and PyEval_ThreadsInitialized() functions
are now deprecated and will be removed in Python 3.11. Calling
PyEval_InitThreads() now does nothing. The GIL is initialized by
Py_Initialize() since Python 3.7. (Contributed by Victor Stinner
in bpo-39877.)
I chose to disable the call with a #if test using PY_VERSION_HEX.
There is precedent for use of PY_VERSION_HEX; it's used in two places
in python-internal.h. I noticed that under certain circumstances
python-internal.h defines PyEval_InitThreads to be nothing, which
accomplishes the same thing. I considered doing something similar for
this case, but decided against it because, at some point in the future,
the presence of PyEval_InitThreads() without some explanation will be
confusing to a reader who won't be able to find PyEval_InitThreads in
the current (future for us) Python API. IMO, use of the #if along
with an accompanying comment seemed more straightforward.
gdb/ChangeLog:
* python/python.c (do_start_initialization): Don't call
PyEval_InitThreads for Python 3.9 and beyond.