[Insight-users] FFTW thread safety

[Cory Quammen]

Simon,

I posted a patch to gerrit. You can review it here:

http://review.source.kitware.com/#/c/8506/

Thanks,
Cory

On Wed, Nov 14, 2012 at 9:53 AM, Cory Quammen <cquammen at cs.unc.edu> wrote:
> Simon,
>
> Thank you for the patch. I will post a patch based on your patch to
> gerrit when I have a moment today, unless someone beats me to it.
>
> Cory
>
> On Wed, Nov 14, 2012 at 9:48 AM, Simon Rit
> <simon.rit at creatis.insa-lyon.fr> wrote:
>> Hi,
>> I have experienced problems with FFTW in ITK 4. I am doing many
>> parallel FFT filters, each parallel thread having the piece of the
>> image defined by ThreadedGenerateData. This is a filter part of
>> www.openrtk.org which code is here:
>> https://github.com/SimonRit/RTK/blob/master/code/rtkFFTRampImageFilter.txx
>>
>> I have originally done that with the code of Gaëtan Lehmann
>> (http://www.insight-journal.org/browse/publication/717) but I had to
>> fix it then for thread safety. I have now moved to ITK4 but I think
>> that the thread safety issue is still here since I have random
>> crashes. The problem is that the destroy functions are not protected
>> by the mutex although they are not thread safe
>> (http://www.fftw.org/doc/Thread-safety.html). So a lock / unlock must
>> be added around it in itkFFTWCommon.h.
>> The patch is below, let me know what you think.
>> Simon
>>
>> PS: It is also worth of note that I have added a Lock/Unlock in the
>> BeforeThreadedGenerateData function of my filter to ensure that the
>> mutex is initialized.
>>
>> The patch:
>>
>> @@ -351,7 +350,9 @@ public:
>>    }
>>    static void DestroyPlan(PlanType p)
>>    {
>> +    FFTWGlobalConfiguration::Lock();
>>      fftwf_destroy_plan(p);
>> +    FFTWGlobalConfiguration::Unlock();
>>    }
>>  };
>>
>> @@ -653,7 +654,9 @@ public:
>>    }
>>    static void DestroyPlan(PlanType p)
>>    {
>> +    FFTWGlobalConfiguration::Lock();
>>      fftw_destroy_plan(p);
>> +    FFTWGlobalConfiguration::Unlock();
>>    }
>>  };
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>
>
>
> --
> Cory Quammen
> Research Associate
> Department of Computer Science
> The University of North Carolina at Chapel Hill



-- 
Cory Quammen
Research Associate
Department of Computer Science
The University of North Carolina at Chapel Hill