[Paraview-developers] ParaView plugins with MPI only on client

Sun Jun 2 03:30:49 EDT 2013

that could be a fine solution if you're not overly concerned about 
portability. if you did that then you might have to use mpiexec(or 
whatever launcher) to start the paraview client. (but mpich and openmpi 
seem to be fine without mpiexec for 1 process runs...ymmv) you'd also be 
prevented from running the client on login nodes at certain hpc sites.

but wait a second...
> Just enabling the Multi-Core option in the ParaView settings does not 
> seem to do the trick.
I think that this should work. at least my reader which can't run 
without mpi works with it. Is this a recent version of ParaVIew? Are you 
sure you tried on an mpi endowed build? Once you check the multicore 
setting you need to restart paraview.

On 06/01/2013 03:20 PM, Biddiscombe, John A. wrote:
>
> Michael,
>
> I had  the same problem with a plugin of mine, so I added some code to 
> call mpi init in the client,
>
> Have a look at this patch. I can't remember why I put in an #ifdef 
> win32 now, (maybe because I usually run the gui on windows and the 
> servers on the cray and probably it needed a tweak on linux...)
>
> https://github.com/biddisco/ParaView/commit/10e4affe2d7a4736d05d1d14cfaffc996c227649
>
> note also I needed thread multiple, so you might be able to simplify 
> it slightly.
>
> This patch might be obsolete, because I think I found a way of doing 
> it inside the plugin...[pause] ... no in the plugin I swap the global 
> communicator from a dummycontroller to a true mpi controller. Try this 
> patch and if it doesn't work I'll point you to my plugin tweaks.
>
> JB
>
> *From:*paraview-developers-bounces at paraview.org 
> [mailto:paraview-developers-bounces at paraview.org] *On Behalf Of *burlen
> *Sent:* 01 June 2013 19:19
> *To:* Michael Schlottke
> *Cc:* ParaView Developers
> *Subject:* Re: [Paraview-developers] ParaView plugins with MPI only on 
> client
>
> Hi Micheal,
>
> I think you better let ParaView start MPI. There is a method that 
> every reader should implement called CanReadFile. If you're reader 
> cannot run with out MPI then in CanReadFile you should check if MPI is 
> initialized and if not then you should return false. Then ParaView 
> will not attempt to use your reader. This will avoid crashes when you 
> are not running in client server mode. Something like this...
>
> 276 
> //-----------------------------------------------------------------------------
> 277 int vtkSQBOVReaderBase::CanReadFile(const char *file)
> 278 {
> 279   #if defined SQTK_DEBUG
> 280   pCerr() << "=====vtkSQBOVReaderBase::CanReadFile" << endl;
> 281   pCerr() << "Check " << safeio(file) << "." << endl;
> 282   #endif
> 283
> 284   int status=0;
> 285
> 286   #ifdef SQTK_WITHOUT_MPI
> 287   (void)file;
> 288   #else
> 289   // first check that MPI is initialized. in builtin mode MPI will
> 290   // never be initialized and this reader will be unable to read files
> 291   // so we always return false in this case
> 292   int mpiOk=0;
> 293   MPI_Initialized(&mpiOk);
> 294   if (!mpiOk)
> 295     {
> 296     return 0;
> 297     }
> 298
> 299   // only rank 0 opens the file, this results in metadata
> 300   // being parsed. If the parsing of md is successful then
> 301   // the file is ours.
> 302 this->Reader->SetCommunicator(MPI_COMM_SELF);
> 303   status=this->Reader->Open(file);
> 304   this->Reader->Close();
> 305   #endif
> 306
> 307   return status;
> 308 }
>
> Of course if ParaView is built without MPI then you should always 
> return false. An even better solution is to structure your reader to 
> work both with and without mpi. I know it's doable if you're using 
> unidata netcdf ver 4, not so sure about pnetcdf...
>
> Burlen
>
> On 06/01/2013 08:15 AM, Michael Schlottke wrote:
>
>     Hi,
>
>     for one of our own ParaView reader plugins we rely on Parallel
>     NetCDF (pnetcdf) to do read in data in parallel, which in turn
>     uses MPI to do the parallel I/O. Principally our reading algorithm
>     works with any number of processes, including one.
>
>     At the moment, we always have to start a pvserver instance with
>     MPI (i.e. mpiexec -n NN pvserver), start a normal client, and
>     connect to the pvserver instance if we want to use the plugin -
>     this also works for NN=1. However, when I start the ParaView
>     client, the plugin crashes because MPI was not loaded/started.
>     Thus we always have to go through the extra steps of starting a
>     pvserver if we want to use the plugin.
>
>     Thus my question is whether there is a way to either start/load
>     MPI manually from the plugin, or if it is possible to configure
>     the client to automatically load and start the MPI library? Just
>     enabling the Multi-Core option in the ParaView settings does not
>     seem to do the trick.
>
>     Regards,
>
>     Michael
>
>     --
>
>     Michael Schlottke
>
>     SimLab Highly Scalable Fluids & Solids Engineering
>
>     Jülich Aachen Research Alliance (JARA-HPC)
>
>     RWTH Aachen University
>
>     Wüllnerstraße 5a
>     52062 Aachen
>     Germany
>
>     Phone: +49 (241) 80 95188
>
>     Fax: +49 (241) 80 92257
>
>     Mail: m.schlottke at aia.rwth-aachen.de
>     <mailto:m.schlottke at aia.rwth-aachen.de>
>
>     Web: http://www.jara.org/jara-hpc
>
>
>
>
>
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