Le 24/09/2019 à 09:29, Antoine Monmayrant a écrit :


Le 23/09/2019 à 23:13, stephane.motte...@utc.fr a écrit :

Hello Antoine,

Before judging that some code is just a "dirty hack" you should first get into the code and see hows things are written. The implementation in 5.5.2 was using OpenMP so I don't see anything dirty here. The implementation was unstable under OSX and Linux, and under Windows parallel_run was just making calls sequentially. So no "dirty hack" under Windows but just a shortcut. Octave does also the same with Matlatb's parfor : it just does things sequentially. However, even unstable, parallel_run was very useful (I used it a lot under Linux to do some Monte Carlo estimation on a 40 processor machine). It is a pity that it's re-engineering for 6.0 familiy was not a priority.

Hello Stephane,

I'm sorry, I did not want to sound rude calling it a "dirty hack".
It's just the explanation I got from scilab developers last time I discussed with them about it. We were trying to get similar performances under linux/osx/windows with some code using parallel_run.

Under OSX parallel_run used to work (a little bit) up to 5.5.1 version, then it was almost unusable.

That was a dead end.

Having any sort of parallel computing under scilab 6.0.2 would be a real step forward for us. I have played a bit with julia to see what it means parallelizing some code in julia.
It was quite easy.

Yeah, Julia has many interesting features but things have been developped with such a kind of orthodoxy that using it is sometimes very baffling...

I don't know whether a similar approach can be implemented in scilab.

The rewritten internals (ast module) would allow to implement (at least) something similar to Matlab's parfor. parallel_run worked by forking the main Scilab process, that's why it was not transposable to Windows (no fork()). Maybe could it be possible with threads with the new architecture ? The only thing that's certain is that without an active collaboration of Antoine Elias this feature will never be developped. The only way is to persuade ESI that it is a strategic feature for their business with Scilab !

S.


Antoine


S.

Quoting Antoine Monmayrant <amonm...@laas.fr <mailto:amonm...@laas.fr>>:

Hello,

Are you using Windows or anything else?
Because as far as I remember, parallel_run is just a dirty hack that only works under windows.
On my linux install of scilab 6.0.2, I also have:
--> parallel_run

Undefined variable: parallel_run

So it might be a bug in the documentation that should mention "windows only" like some other functions.

Antoine


Le Lundi, Septembre 23, 2019 15:46 CEST, fujimoto2005 <fujimoto2...@gmail.com <mailto:fujimoto2...@gmail.com>> a écrit:

I wanted to use "parallel_run" and tried the sample script in the help page.
But it did not work with the error message "undefined
variable:parallel_run".
Please teach me what is wrong?

The sample script I used is as follows
******
for i = 1:10
  res(i) = i*i;
end;
// for parallel_run, we need to have a function performing the computation
function a=g(arg1)
  a=arg1*arg1
endfunction

res = parallel_run(1:10, g);
// => res = [1  4  9  16  25  36  49  64  81  100];
*********





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Stéphane Mottelet
Ingénieur de recherche
EA 4297 Transformations Intégrées de la Matière Renouvelable
Département Génie des Procédés Industriels
Sorbonne Universités - Université de Technologie de Compiègne
CS 60319, 60203 Compiègne cedex
Tel : +33(0)344234688
http://www.utc.fr/~mottelet

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