Re: [Libmesh-users] problems with mesh output

[Michael P. <mpo...@pu...>]

Hi John,

It would be absolutely impossible for me to use Mesh on MPI_COMM_WORLD.

Do you thing, will it possible either to reset the vtkMPIController or 
to split his communicator?

Michael.


On 06/13/2018 12:28 PM, John Peterson wrote:
>
>
> On Wed, Jun 13, 2018 at 10:14 AM, Michael Povolotskyi 
> <mpo...@pu... <mailto:mpo...@pu...>> wrote:
>
>     Thank you John,
>
>     I do have some MPI code before LibMeshInit in my real application.
>
>     Also, If I do not call MPI_Finalize at the very end I'm getting
>     warning messages from MPI.
>
>     Thank you for you explanation with .pvtu, I have changed my code
>     to  libMesh::VTKIO out(mesh); out.write("mesh1.pvtu");   and this
>     worked.
>
>     Do you have any suggestions for  the Problem #2 that I reported?
>
>     It seems to me that the problem is that the communicator of the
>     Mesh object is smaller than the communicator of the VTK. This
>     causes a problem for me.
>
>
> Hmm, I don't think we have considered this use case in the past, the 
> vtkMPIController is initialized in libmesh.C, and it must be assuming 
> MPI_COMM_WORLD...
>
>   _vtk_mpi_controller = vtkMPIController::New();
>   _vtk_mpi_controller->Initialize(&argc, const_cast<char ***>(&argv), 
> /*initialized_externally=*/1);
> _vtk_mpi_controller->SetGlobalController(_vtk_mpi_controller);
>
> In order for the parallel VTK writer to work, the Mesh probably 
> therefore also needs to be using MPI_COMM_WORLD.
>
> -- 
> John