There isn't really any contention for these memory locations in
CPython as it stands because only one interpreter thread can run at a
time. The only time a cache handoff is needed is during a thread
switch when the new thread is scheduled on a different core, which is
pretty rare (at CPU timescales). Adding checks to every incref/decref
would probably cost more time than it would save.
Something that might help performance a bit, and wouldn't hurt it,
would be to drop explicit calls of
Py_{INC,DEC}REF(Py_{None,False,True,...}), such as the ones in
Py_RETURN_{NONE,FALSE,TRUE}, making these objects' refcounts into
freefloating meaningless values. The refcounts would be initially set
to a value far from zero, and on the rare occasions that they hit
zero, the dealloc functions would just set them back to the initial
value. Whether this would save enough time to be worth it, I don't
know.
(To avoid signed wraparound undefined behavior, you'd have to either
change the refcount type from ssize_t to size_t, or else keep the
DECREF calls and set the initial value to something like
PY_SSIZE_T_MAX/2.)
_______________________________________________
Python-ideas mailing list -- python-ideas@python.org
To unsubscribe send an email to python-ideas-le...@python.org
https://mail.python.org/mailman3/lists/python-ideas.python.org/
Message archived at
https://mail.python.org/archives/list/python-ideas@python.org/message/76JRO673TWG7WNPWPD76ZCRLA4PM6EJA/
Code of Conduct: http://python.org/psf/codeofconduct/
