[Stackless] multi-core processing?

Simon Pickles sipickles at googlemail.com
Mon Jun 16 14:27:27 CEST 2008

Chris Lee wrote:
> On Jun 15, 2008, at 10:33 PM, Jeff Senn wrote:
>> On Jun 15, 2008, at 3:57 PM, Simon Pickles wrote:
>>> Hi NRB,
>>> Neutral Robot Boy wrote:
>>>> alright, so i'm still in 'beginner' mode with stackless here. i did 
>>>> a bit of reading which suggested that stackless should be able to 
>>>> distribute processing across multiple cores without trouble, and i 
>>>> decided to write a really simple script and look at how much of a 
>>>> load it puts on my cpu.
>>> The stackless scheduler which you activate by calling 
>>> stackless.run() only runs in one thread. Each tasklet is added to 
>>> that scheduler and called in turn. No other core will be used.
>> I suppose one should point out that this is not merely a limitation 
>> of Stackless.
>> e.g. running schedulers in more than one thread won't even help.
>> Python itself, even using multiple native threads, can only make use 
>> of one core
>> at a time due to the GIL (Global Interpreter Lock).  If you are 
>> interested
>> in the whys-and-wherefores, a search through the archives of this list
>> (and/or Google) will provide a bunch of discussions.
>> -Jas
> Yes indeed, I run simulation code which can benefit from as many cores 
> and processors that are available. To achieve this in python I used 
> parallelpython, which acts as a job server and pickles the parameters, 
> modules, and functions for use by a new instance of python. Using 
> this, I can pretty much use all the processing power available on the 
> computer. It can even run across multiple machines, if I go to the 
> trouble to set up the permissions on each machine.
Really? eek, I had misunderstood the GIL, I think. So Carlos's example 
is multicore but not parallel?

Thats bad for me. My server had several interpreters running 
'concurrently' using twisted.PerspectiveBroker to communicate. I guess 
this model works for clusters but not for SMPs.....

eek again!


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