[MOAB-dev] loading a VTK mesh in parallel (.pvtu)

[Lorenzo Alessio Botti]

> You cannot call resolve_shared_entities unless you have a tag like a global id tag, or a file id tag that uniquely identifies every node.
> You need to use ParallelMerge;
> in there, assuming that the meshes are matching between processes, within some tolerance, you just need to run merge.
> 
> Basically, a skin is computed first on each processor, and the skin is "resolved" in parallel using a 2 way communication, similar to resolve shared entities.
> 
> ( each vertex on the skin is first sent to a "working processor" , established based on a pre-determined pattern; the working processor is guaranteed to receive all instances of the vertex on all processes; it decides then what vertices need to be "merged" because they are identical within some geometric tolerance; that information is then communicated back to all processes that sent that vertex)

Dear Iulian,
thanks for the reply.
ParallelMerge might be useful in many situations and I was not aware of it, so thanks for the hint. 
However, I actually have available global node ids, and therefore I'm able to resolve shared and exchange ghost entities in parallel. This is working quite well.
What I want to achieve is do the work is serial (e.g. in the partitioning phase) instead of doing it parallel, then store the informations on the mesh files and finally load the files in parallel reading all the data I need.
I’d like to know which informations I need to store on the files in order to be able to exchange tags across the processes once the mesh is loaded in a distributed way. 
For example I guess I need to store informations regarding the processors sharing the entities and the parallel status of each entity. 

The reason for doing so is that in serial some situations are easier to manage, e.g. tag entities as shared on periodic boundaries and decide who they are going to communicate with. 
The possibility to resolve in parallel is great in case that the mesh is repartitioned in parallel but if the mesh does not change during the computations doing part of the work in serial in a preliminary phase gives me more control (at least this is my perception).

Thanks again.
Bests.
Lorenzo
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