[Paraview] capability of ParaView, Catalyst in distributed computing environment ...

[u.utku.turuncoglu at be.itu.edu.tr]

Yes, you are right. In this case, there will be two separate
MPI_COMM_WORLD. Plus, one that covers all the resources (let's say that
global MPI_COMM_WORLD). Actually, this kind of setup is very common for
multi-physics applications such as fluid-structure interaction. So, is it
possible to tight this kind of environment with Catalyst? I am not expert
about Catalyst but it seems that there might be a problem in the rendering
stage even underlying grids and fields are defined without any problem.

Regards,

--ufuk

> I'm not sure if this is exactly what the original user is referring to,
> but it is possible to have two separate codes communicate using MPI
> through the dynamic processes in MPI-2. Essentially, one program starts up
> on N processors and begins running and gets an MPI_COMM_WORLD. It then
> spawns another executable on M different processors and that new
> executable will call MPI_INIT and also get its own MPI_COMM_WORLD. So you
> have two, disjoint MPI_COMM_WORLD's that get linked together through a
> newly created intercommunicator.
>
>
> I've used this to couple a structural mechanics code to our fluid dynamics
> solver for example. It sounds like that is similar to what is being done
> here.
>
>
> How that would interact with coprocessing is beyond my knowledge though.
> It does sound like an interesting problem and one I would be very curious
> to find out the details.
>
>
> Tim
>
>
> ________________________________
> From: ParaView <paraview-bounces at paraview.org> on behalf of Andy Bauer
> <andy.bauer at kitware.com>
> Sent: Wednesday, May 18, 2016 10:52 AM
> To: Ufuk Utku Turuncoglu (BE)
> Cc: paraview at paraview.org
> Subject: Re: [Paraview] capability of ParaView, Catalyst in distributed
> computing environment ...
>
> Hi,
>
> I'm a bit confused. MPI_COMM_WORLD is the global communicator and as far
> as I'm aware, can't be modified which means there can't be two different
> communicators.
>
> Catalyst can be set to use a specific MPI communicator and that's been
> done by at least one code (Code_Saturne). I think they have a multiphysics
> simulation as well.
>
> Cheers,
> Andy
>
> On Wed, May 18, 2016 at 5:22 AM, Ufuk Utku Turuncoglu (BE)
> <u.utku.turuncoglu at be.itu.edu.tr<mailto:u.utku.turuncoglu at be.itu.edu.tr>>
> wrote:
> Hi All,
>
> I just wonder about the capability of ParaView, Catalyst in distributed
> computing environment. I have little bit experience in in-situ
> visualization but it is hard for me to see the big picture at this point.
> So, i decided to ask to the user list to get some suggestion from the
> experts. Hypothetically, lets assume that we have two simulation code that
> are coupled together (i.e. fluid-structure interaction) and both of them
> have their own MPI_COMM_WORLD and run on different processors (model1 runs
> on MPI rank 0,1,2,3 and model2 runs on 4,5,6,7). What is the correct
> design to create integrated in-situ visualization analysis (both model
> contributes to same visualization pipeline) in this case? Do you know any
> implementation that is similar to this design? At least, is it possible?
>
> In this case, the adaptor code will need to access to two different
> MPI_COMM_WORLD and it could run on all processor (from 0 to 7) or its own
> MPI_COMM_WORLD (i.e. MPI ranks 8,9,10,11). Also, the both simulation code
> have its own grid and field definitions (might be handled via defining
> different input ports). Does it create a problem in Paraview, Catalyst
> side, if the multiblock dataset is used to define the grids of the
> components in adaptor. I am asking because some MPI processes (belongs to
> adaptor code) will not have data for specific model component due to the
> domain decomposition implementation of the individual models. For example,
> MPI rank 4,5,6,7 will not have data for model1 (that runs on MPI rank
> 0,1,2,3) and 0,1,2,3 will not have data for model2 (that runs on MPI rank
> 4,5,6,7). To that end, do i need to collect all the data from the
> components? If this is the case, how can i handle 2d decomposition
> problem? Because, the adaptor code has no any common grid structure that
> fits for all the model components.
>
> Regards,
>
> Ufuk Turuncoglu
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