Re: [Libmesh-users] How to use ExodusII_IO::copy_elemental_solution in parallel?

[John P. <jwp...@gm...>]

On Fri, Oct 20, 2017 at 9:19 AM, David Knezevic <dav...@ak...>
wrote:

> I'm using ExodusII_IO::copy_elemental_solution to copy element data to a
> new System object, and this works fine in serial using code like the below:
>
> ----------------------------------------------
>
>   Mesh mesh(comm);
>   ExodusII_IO exo_io(mesh);
>
>   if (comm.rank() == 0)
>   {
>     exo_io.read(path_to_mesh_file);
>   }
>   MeshCommunication().broadcast(mesh);
>
>   mesh.prepare_for_use();
>
>   EquationSystems es(mesh);
>   ExplicitSystem& materials_system =
>     es->add_system<ExplicitSystem> ("data");
>   materials_system.add_variable ("data", CONSTANT, MONOMIAL);
>   es->init();
>
>   exo_io.copy_elemental_solution(es, "data", "data");
>
> ----------------------------------------------
>
>
> However, in parallel I hit the error "ERROR, ExodusII file must be opened
> for reading before copying an elemental solution!" at the start of
> copy_elemental_solution.
>
> As far as I know (e.g. based on namebased_io.C) we should only call "read"
> on proc 0, so I don't see how to make this work in parallel, since in that
> case exo_io is only "opened for reading" on proc 0.
>
> Does anyone have any suggestions on this? (John, I gather that you were
> the author of most of the ExodusII reader stuff, so I thought you might
> know the answer?)
>

Hmm... I think copy_elemental_solution() is only designed to work in
serial, so could we just guard the parts the parts of that function that
read from the file in "if (rank==0)"?

In addition, we would only error out if the file is not open for reading on
proc 0...

-- 
John