[Paraview-developers] Parallel structured grid reader doesn"t produce subextent

[Mizael Moser, Markus Klaus]

Dear ParaView developers,

I'm having trouble to parallelize my ParaView reader plugin. I want to read HDF5 files and the grid is a structured grid. The plugin works perfectly fine if run in serial, and if i run it in parallel the solution is also correct but instead of dividing the dataset in x subsets, it reads the whole dataset x times(for each processor 1 time).


I found the wiki for a structured grid parallel reader (http://www.paraview.org/Wiki/Writing_ParaView_Readers) and used it as orientation.


My RequestInformation looks like this:


//Reading basic information

//Reading in the extent from the file

int extent[6];

//storing the extent in the array

vtkInformation* outInfo=outputVector->GetInformationObject(0);

outInfo->Set(CAN_HANDLE_PIECE_REQUEST(),1);

outInfo ->Set(vtkStreamingDemandDrivenPipeline::WHOLE_EXTENT(),extent,6);



RequestData looks like this:


vtkProcessModule *ParInfo;
vtkInformation *outInfo = outputVector->GetInformationObject(0);
vtkMultiBlockDataSet* multiBlock = vtkMultiBlockDataSet::SafeDownCast(outInfo->Get(vtkDataObject::DATA_OBJECT()));

int subext[6];
outInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT(),subext);

cout<<"Num of Processors = "<<ParInfo->GetNumberOfLocalPartitions()<<endl;

cout<< "subext from rank"<< ParInfo->GetPartitionId() << " " <<subext[0]<<.......<<.....<< ex[5] <<endl;

//Reading the grid and the data-set


Lets say the extent is 50x120x150 and i start the server with
mpirun -np 2 pvs and connecting the client i get the following "output":

Num of Processors = 2
Num of Processors = 2
subext from rank0 0 50 0 120 0 150
subext from rank1 0 50 0 120 0 150
But at the end the Dataset is still visualized correctly.


Normally "outInfo->Get(vtkStreamingDemandDrivenPipeline::UPDATE_EXTENT(),subext);" should produce the sub-extent for the rank or am i wrong?

What am I doing wrong, or what do I have to do to get the sub-extent?


Thank you very much in advance,
Markus Moser


Markus Moser
Student assistant

Chair of Fluid Mechanics and Institute of Aerodynamics

Wüllnerstraße 5a
RWTH Aachen University

52062 Aachen
Germany





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