multi threading in multi processor (computer)

[Jeremy Jones]

Pierre Barbier de Reuille wrote:

> ajikoe at gmail.com a écrit :
>
>> Hello,
>>
>> Is anyone has experiance in running python code to run multi thread
>> parallel in multi processor. Is it possible ?
>>
>> Can python manage which cpu shoud do every thread?
>>
>> Sincerely Yours,
>> Pujo
>>
>
> There's just no way you can use Python in a multi-processor environment,

This isn't exactly correct.  There is no way with plain, out of the box 
Python (and writing plain Python code) to take full advantage of 
multiple processors using a single process.  A single plain vanilla 
Python process will saturate at most one CPU.  I think that's what you 
were trying to express, but I thought it would be best to clarify.  The 
machine I'm running on right now is a dual-CPU machine.  I can 
*definitely* run Python on it.  I haven't tried threading just yet since 
it's a new-to-me machine.  But if I were to watch gkrellm, I would 
expect to see a CPU intensive (multithreaded) process flip back and 
forth between the two CPUs, taking its turn totally saturating both of 
them, one at a time.


> because the GIL (Global Interpreter Lock) will prevent two threads 
> from running concurrently. When I saw this discussed, the Python 
> developper were more into multi-process systems when it comes to 
> multi-processors.
> I think I even heard some discussion about efficient inter-process 
> messaging system, but I can't remember where :o)
>
> Hope it'll help.
>
> Pierre

Jeremy Jones