[$] A per-interpreter GIL

'Subinterpreters', which are separate Python interpreters running in the
same process that can be
created using
the C API, have been a part of Python since the previous century
(version 1.5 in 1997), but they are largely unknown and unused.
Eric Snow has been on something of a quest, since 2015 or so, to bring
better multicore processing to Python by
way of subinterpreters (or 'multiple interpreters'). He has made it part
of the way there, with the
adoption of a separate global interpreter lock (GIL) for each
subinterpreter, which
was added for Python 3.12. Back in April, Snow gave a talk (YouTube video) at
PyCon about multiple interpreters, their status, and his plans for the
feature in
the future.