[Paraview] problem with parallel filter, segfault after last process returns

[Christine Corbett Moran]

Berk, Burlen,

Yes this was exactly what was happening. I had allocated too small of
a buffer to receive a piece of data, which corrupted memory and was
only a problem on returning the function. Doh!; I was looking for
bigger issues when it was basic.

Cheers,
Christine

On Fri, Nov 6, 2009 at 10:35 PM, Berk Geveci <berk.geveci at kitware.com> wrote:
> This makes me think that something is writing beyond the bounds of an
> array corrupting memory. Any chance you can run this within valgrind?
>
> On Fri, Nov 6, 2009 at 12:34 PM, Christine Corbett Moran
> <corbett at physik.uzh.ch> wrote:
>> Hi,
>>
>> I'm converting my serial filters to work in parallel. In this process,
>> I'm run into trouble at the very last stage, after verifying that at
>> every stage, on every processor,  that correct data was being
>> sent/received, and that the final output was identical to the
>> algorithm as run in serial.
>>
>> The entire method runs as planned, but immediately after returning
>> from the RequestData method on processes 0 (the last one to return as
>> I have process 0 receiving data sent by other processes, and perform a
>> final computation). I get a segfault:
>> "*** Process received signal ***
>>  Signal: Segmentation fault (11)
>> Signal code:  (128)
>> Failing at address: (nil)"
>>
>> I initially thought this had something to do with the way I am using
>> the output vector. So as a test, I simply copy the input to the output
>> before doing all my computations taking into account the controller,
>> check these computations at every step, but actually ignore their
>> output in the end
>>
>> pseudocode for my test
>> RequstData:
>> 1. copy input to output
>> 2. if there's a controller specified and number of processors>1,
>> perform parallel computation using controller, otherwise perform
>> serial computation. I don't actually store the result
>> 3. Return
>>
>> The segfault is not present on returning if I comment out all code in
>> step 2, or if the algorithm is run in serial. I know the segfault
>> happens after RequestData returns on process  Since in this test case,
>> all computations in 2. are local with no results written to output, I
>> am not sure what is going on. Do I need to do something special to
>> "shutdown" the controller? My destructor uses
>> vtkCxxSetObjectMacro(vtkCenterOfMassFilter,Controller,
>> vtkMultiProcessController);
>> via
>> this->SetController(0);
>> but the segfault is still present if I comment this out. My controller
>> was set in the constructor via
>> this->SetController(vtkMultiProcessController::GetGlobalController());
>>
>> Christine
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>