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Re: GIL in alternative implementations

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On Monday, June 6, 2011 9:03:55 PM UTC-7, Gabriel Genellina wrote:
> En Sat, 28 May 2011 14:05:16 -0300, Steven D'Aprano  
> <steve+comp....@pearwood.info> escribi�:
> 
> > On Sat, 28 May 2011 09:39:08 -0700, John Nagle wrote:
> >
> >> Python allows patching code while the code is executing.
> >
> > Can you give an example of what you mean by this?
> >
> > If I have a function:
> >
> >
> > def f(a, b):
> >     c = a + b
> >     d = c*3
> >     return "hello world"*d
> >
> >
> > how would I patch this function while it is executing?
> 
> I think John Nagle was thinking about rebinding names:
> 
> 
> def f(self, a, b):
>    while b>0:
>      b = g(b)
>      c = a + b
>      d = self.h(c*3)
>    return "hello world"*d
> 
> both g and self.h may change its meaning from one iteration to the next,  
> so a complete name lookup is required at each iteration. This is very  
> useful sometimes, but affects performance a lot.

It's main affect performance is that it prevents an optimizer from inlining a function call(which is a good chunk of the payoff you get in languages that can do that).

I'm not sure where he gets the idea that this has any impact on concurrency, though.


Carl Banks

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Re: GIL in alternative implementations Carl Banks <pavlovevidence@gmail.com> - 2011-06-07 10:08 -0700

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