[Symphony] Symphony in a shared-memory architecture

[Ted Ralphs]

If you can send a file that this this happens on, we'll look at it.

Cheers,

Ted

On Wed, Feb 9, 2011 at 3:09 PM, Aiko Vogelsang <aikovogelsang at gmx.de> wrote:
> Hello everybody,
>
> at first thanks for the answer! The selection of the max. active nodes works
> fine.
>
> But with the parallelization another problem occurred. If I use Symphony in
> parallel I get a "Segmentation fault" after some calculations. If I use a
> sequential version of Symphony for exactly the same problem (the only
> difference in this case is "sym_set_int_param(env,  "max_active_nodes",
> 1);") everything looks like expected before (no failure).
>
> Secondly, if I get no segmentation fault (happens sometimes), the results of
> the calculation in parallel differ from the sequential case.
>
> Is it possible that there's a still a race condition between the threads? If
> so, I wouldn't understand it because I configured the solver for a parallel
> environment.
>
> Does anybody have an idea what can be wrong here or where I could have a
> look at?
>
> Again many thanks in advance for your support (I'm sorry to keep bothering
> you with my problem)!
>
> Best regards
> Aiko
>
>
> -----Ursprüngliche Nachricht-----
> Von: Ted Ralphs [mailto:ted at Lehigh.EDU]
> Gesendet: Montag, 7. Februar 2011 17:30
> An: Aiko Vogelsang
> Cc: symphony at list.coin-or.org
> Betreff: Re: [Symphony] Symphony in a shared-memory architecture
>
> The parameter "max_active_nodes" controls how many threads are used
> with OpenMP. To set that parameter through the API, do, e.g.,
>
> sym_set_int_param(env,  "max_active_nodes", 8);
>
> Let me know if that fixes your problem.
>
> Cheers,
>
> Ted
>
> On Thu, Feb 3, 2011 at 5:12 AM, Aiko Vogelsang <aikovogelsang at gmx.de> wrote:
>> Hello everybody,
>>
>> I've a question on how to use Symphony in a shared-memory architecture
> again.
>>
>> Because of the hints I got last month I compiled Symphony with the option
> "--enable-openmp". Everything works fine during compiling and installing.
>> If I invoke the solver from the command line with the option "-p 4"
> Symphony works in parallel (as I read in the manual).
>>
>> But if I include the header files and the library files of Symphony and
> the related projects into my C++ project the solver still works in
> sequential. I tried to insert some compiler (which is GCC 4.5) options but
> nothing worked.
>> According to my understanding I need an additional option compareable to
> "-p 4" that would be inserted in the command line.
>>
>> If I could get a hint for this problem it would be very helpful! Many
> thanks in advance!
>>
>> Best regards
>> Aiko
>>
>> _______________________________________________
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>> Symphony at list.coin-or.org
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>>
>
>
>
> --
> Dr. Ted Ralphs
> Associate Professor, Lehigh University
> (610) 628-1280
> ted 'at' lehigh 'dot' edu
> coral.ie.lehigh.edu/~ted
>
>
> _______________________________________________
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> http://list.coin-or.org/mailman/listinfo/symphony
>



-- 
Dr. Ted Ralphs
Associate Professor, Lehigh University
(610) 628-1280
ted 'at' lehigh 'dot' edu
coral.ie.lehigh.edu/~ted