maximum number of threads limitation?

[MESSAOUDI Cédric]

Hi,

I have a computer with 40 cores with HT (so maximum number of threads is 80).
With ImageJ, I changed the parallel threads property via Edit>Memory and threads, I could give any number so in my case 80 (instead of the default 32)

But when I checked again the value, it was reduced to 32 threads. It seems I can't allocate more than 32 threads.

I looked at source code and found that this limitation is present in the class Prefs method setThreads(int n)
Where I found this instruction
if (n>32) n = 32;

so there is a hard-coded limitation to 32 threads.

Is there any (good) reason for this limitation to 32 threads?

Best regards,
Cédric

----------------------------------------------------------
Cédric MESSAOUDI
Institut Curie - INSERM U759 Laboratoire d'Imagerie Intégrative
Centre Universitaire - Bât 112,
Rue Henri Becquerel
91405 Orsay CEDEX
France
----------------------------------------------------------
Tel : [phone]
       [phone]
----------------------------------------------------------
[hidden email]<mailto:[hidden email]>
----------------------------------------------------------


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[Rasband, Wayne (NIH/NIMH) [E]]

On May 15, 2014, at 2:55 AM, Messaoudi Cedric wrote:

> Hi,
>
> I have a computer with 40 cores with HT (so maximum number of threads is 80).
> With ImageJ, I changed the parallel threads property via Edit>Memory and threads, I could give any number so in my case 80 (instead of the default 32)
>
> But when I checked again the value, it was reduced to 32 threads. It seems I can't allocate more than 32 threads.

The 32 thread limitation is removed in ImageJ 1.49a.

-wayne

> I looked at source code and found that this limitation is present in the class Prefs method setThreads(int n)
> Where I found this instruction
> if (n>32) n = 32;
>
> so there is a hard-coded limitation to 32 threads.
>
> Is there any (good) reason for this limitation to 32 threads?
>
> Best regards,
> Cédric
>
> ----------------------------------------------------------
> Cédric MESSAOUDI
> Institut Curie - INSERM U759 Laboratoire d'Imagerie Intégrative
> Centre Universitaire - Bât 112,
> Rue Henri Becquerel
> 91405 Orsay CEDEX
> France
> ----------------------------------------------------------
> Tel : [phone]
>       [phone]
> ----------------------------------------------------------
> [hidden email]<mailto:[hidden email]>
> ----------------------------------------------------------
>
>
> --
> ImageJ mailing list: http://imagej.nih.gov/ij/list.html

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ImageJ mailing list: http://imagej.nih.gov/ij/list.html