Jeremy Kloth <jeremy.kl...@gmail.com> added the comment:
> The problem is to make Py_INCREF/Py_DECREF efficient. That is exactly why I didn't propose a change to them. The singletons still are refcounted as usual, just that their ob_refcnt is ignored. If they somehow reach 0, they just "resurrect" themselves and ignore the regular collection behavior. In the presence of multiple DECREF'ers, the ob_refcnt field is garbage, but that is OK as it is effectively ignored. Practicality vs Purity and all that. > Last time someone tried to use an atomic variable for ob_refcnt, it was 20% > slower if I recall correctly. If many threads start to update such atomic > variable, the CPU cacheline of common singletons like None, True and False > can quickly become a performance bottleneck. Exactly so, hence why I chose the simple solution of effectively ignoring ob_refcnt. > On the other side, if each interpreter has its own objects, there is no need > to protect ob_refcnt, the interpreter lock protects it. My solution also does not need any protection around ob_refcnt. ---------- nosy: +jeremy.kloth _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue39511> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
