Status of Python threading support (GIL removal)?

Jure Erznožnik jure.erznoznik at
Sat Jun 20 00:10:17 CEST 2009

On Jun 19, 11:59 pm, Jesse Noller <jnol... at> wrote:
> On Fri, Jun 19, 2009 at 12:50 PM, OdarR<Olivier.Da... at> wrote:
> > On 19 juin, 16:16, Martin von Loewis <martin.vonloe... at hpi.uni-:
> >> If you know that your (C) code is thread safe on its own, you can
> >> release the GIL around long-running algorithms, thus using as many
> >> CPUs as you have available, in a single process.
> > what do you mean ?
> > Cpython can't benefit from multi-core without multiple processes.
> > Olivier
> Sorry, you're incorrect. I/O Bound threads do in fact, take advantage
> of multiple cores.

Incorrect. They take advantage of OS threading support where another
thread can run while one is blocked for I/O.
That is not equal to running on multiple cores (though it actually
does do that, just that cores are all not well utilized - sum(x) <
100% of one core).
You wil get better performance running on single core because of the
way GIL is implemented in all cases.

More information about the Python-list mailing list