[Python-Dev] GIL, Python 3, and MP vs. UP (was Re: Variant of removing GIL.)

John J Lee jjl at pobox.com
Tue Sep 20 22:27:23 CEST 2005

On Sun, 18 Sep 2005, Guido van Rossum wrote:
> On 9/17/05, John J Lee <jjl at pobox.com> wrote:

> If my hunch is right, I expect that instead of writing massively
> parallel applications, we will continue to write single-threaded
> applications that are tied together at the process level rather than
> at the thread level.

I tend to agree.

> > I realize that not all algorithms (nor all computational problems) scale
> > well to MP hardware.  Is it feasible to usefully compile both MP and a UP
> > binaries from one Python source code base?
> That's an understatement. I expect that *most* problems (even most
> problems that we will be programming 10-20 years from now) get little
> benefit out of MP.

Perhaps, but I suspect we'll also get better at thinking up multiprocessor
algorithms when better motivated by lack of exponential uniprocessor speed
increases.  <ducks, fearing barrage of theorems...>

> > Of course, it still takes a (anti-)hero to step forward and do the work...
> Be my guest. Prove me wrong. Talk is cheap; instead of arguing my
> points (all of which can be argued ad infinitum), come back when
> you've got a working GIL-free Python. Doesn't have to be CPython-based
> -- C# would be fine too.

I don't actively want a GIL-free Python.  I was just making some arguments
in favour of GIL-removal that I hadn't seen made on a public list before.  
(In particular, removal now, since now is a special time.)


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