ParMETIS_V3_PartKway gives some processors 0 nodes

I am partitioning a triangle based finite element mesh using ParMETIS. At some processor counts, ParMETIS_V3_PartKway is giving some processors 0 nodes and not scheduling any nodes to be placed on the processor.

Has anyone else experienced this, or is this a possible issue in how we are sending the mesh informatin to ParMETIS_V3_PartKway?


RE: Sometimes this can happen

Sometimes this can happen when you are partitioning a small graph relative to the number of processors. Is the overall balance still within the specified bounds? That is, max/average less than 1.05 or so?

RE: I also meet this kind of

I also meet this kind of problems, though I call ParMETIS_V3_PartMeshKway() instead. I have 5 processes and the mesh is small, with only 15 elements. In my test, P0~P4 gets 4, 0, 4, 3, 4 elements respectively. In my code, ncon = 1 and ubvec[0] = 1.05.

This is annoying since I remember the manual says to call ParMETIS_V3_PartMeshKway, each process must have at least one element. That means with this partitioning result, I can not repartitioning the mesh again.

Is my understanding correct? How to avoid this phenomenon?