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Date: Tue,  3 Mar 2009 16:33:30 +0100
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From: hugo rivera <uair00@gmail.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
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Subject: Re: [9fans] threads vs forks
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thanks a lot guys.
I think I should study this issue in greater detail. It is not as easy
as I tought it would be.

2009/3/3, David Leimbach <leimy2k@gmail.com>:
>
>
> On Tue, Mar 3, 2009 at 3:52 AM, hugo rivera <uair00@gmail.com> wrote:
> > Hi,
> > this is not really a plan 9 question, but since you are the wisest
> > guys I know I am hoping that you can help me.
> > You see, I have to launch many tasks running in parallel (~5000) in a
> > cluster running linux. Each of the task performs some astronomical
> > calculations and I am not pretty sure if using fork is the best answer
> > here.
> > First of all, all the programming is done in python and c, and since
> > we are using os.fork() python facility I think that it is somehow
> > related to the underlying c fork (well, I really do not know much of
> > forks in linux, the few things I do know about forks and threads I got
> > them from Francisco Ballesteros' "Introduction to operating system
> > abstractions").
>
> My knowledge on this subject is about 8 or 9 years old, so
> check with your local Python guru....
>
> The last I'd heard about Python's threading is that it was cooperative only,
> and that you couldn't get real parallelism out of it.  It serves as a means
> to organize your program in a concurrent manner.
>
> In other words no two threads run at the same time in Python, even if you're
> on a multi-core system, due to something they call a "Global Interpreter
> Lock".
>
> >
> > The point here is if I should use forks or threads to deal with the job at
> hand?
> > I heard that there are some problems if you fork too many processes (I
> > am not sure how many are too many) so I am thinking to use threads.
> > I know some basic differences between threads and forks, but I am not
> > aware of the details of the implementation (probably I will never be).
> > Finally, if this is a question that does not belong to the plan 9
> > mailing list, please let me know and I'll shut up.
> > Saludos
> >
>
> I think you need to understand the system limits, which is something you can
> look up for yourself.  Also you should understand what kind of runtime model
> threads in the language you're using actually implements.
>
> Those rules basically apply to any system.
>
> >
> > --
> > Hugo
> >
> >
>
>


--
Hugo