multiple execution of Image Reader when running PV in parallel
This issue was created automatically from an original Mantis Issue. Further discussion may take place here.
I am having trouble developping a custom reader (public inheritance of vtkImageAlgorithm). When running PV on a single node, my reader executes once only - as expected - and creates a vtkImageData. I can then use any number of Filters downstream
When running PV on multiple nodes, my reader executes every time I start a new filter. Can't figure out what triggers it.
Forget about my own source code. I went back to the basics and put a DebugOn() statement in vtkImageReader. It exhibits exactly the same behavior:
on a single node, execute once and only once as expected. on multiple nodes, executes multiple times. Here is an example running on 2 nodes,
First read of a 90^3 raw binary file (the extents are split in the Z direction):
Reading extent: 0, 89, 0, 89, 0, 45 Reading extent: 0, 89, 0, 89, 43, 89
then I extracted a I=29 ortho-slice and the reader executed again
Reading extent: 29, 29, 0, 89, 0, 89 Reading extent: 29, 29, 0, 89, 0, 89
then I extracted an J=45 orthoslice and the reader executed again Reading extent: 0, 89, 45, 45, 0, 89 Reading extent: 0, 89, 45, 45, 0, 89
then I executed an isosurface and the reader executed again
Reading extent: 0, 89, 0, 89, 0, 45 Reading extent: 0, 89, 0, 89, 43, 89
We have only found this multiple execution with ImageData. Other readers (for example for StructuredGrid) do not execute multiple times.