[Python-Dev] deja-vu .. python locking

Josiah Carlson jcarlson at uci.edu
Wed Sep 20 09:49:59 CEST 2006

Martin Devera <devik at cdi.cz> wrote:
> Even if you can do fast atomic inc/dec, it forces cacheline with
> refcounter to ping-pong between caches of referencing cpus (for read only
> class dicts for example) so that you can probably never get good SMP
> scalability.

That's ok.  Why?  Because according to Guido, the GIL isn't going away:
... so ruminations about refcounting, GC, etc., at least with regards to
removing the GIL towards some sort of "free threading" Python, are
likely to go nowhere.  Unless someone is able to translate the codebase
into using such methods, show how it is not (significantly) more
difficult to program extensions for, show a mild to moderate slowdown on
single processors, and prove actual speedup on multiple processors.  But
even then it will be a difficult sell, as it would require possibly
radical rewrites for all of the hundreds or thousands of CPython
extensions currently being developed and maintained.

 - Josiah

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