Reply To: Manipulating populations with postprocessors on GPU
Thanks for these additional details and good to know that the same problem occurs on CPU. Looking at your debug output I suspect that the issue is a out-of-bounds / undefined access to a neighbor cell (leading to the most likely invalid cell index of ~2e9, especially considering the index of the original cell). Looking at your interpolation function I can not exclude the possibility that very far / out of bounds neighbors are accessed. For performance reasons the index validity is not checked by default leading to the segfault we observe.
What is the max range of neighbors accessed from a cell? Did you consider that the overlap needs to be large enough to cover these accesses (if the post processor is executed at the outermost non-overlap cells). The issue might also be faulty initialization of your extent fields.
Side note: It seems to me that e.g. DOMAIN_EXTENT could be a parameter instead of a per-cell field. Using parameters where possible will help reduce your memory load.