CFD Online Discussion Forums - Problem with Application based on a faceZone in parallel

Dear FOAMers,
I'm working on a new application which does some calculation based on the pressure values provided on a faceZone.

When I run the case in parallel and make sure that each processor mesh contains parts of the faceZone the calculation runs smoothly and yields the correct results. For information on the parallelization see this thread http://www.cfd-online.com/Forums/ope...tml#post595977

But when one processor mesh contains no faces of the faceZone the application halts and just hangs without doing nothing.

I tried do construct and execute the calculation based on the size of the zoneMesh in the following way to keep the not concerned processor from doing the calculation

Code:

// in constructor

if(zoneFaces.size()==0) // no face of faceZone on processor

{

  // create the variable i want to calculate 

  // with the correct size and equal to zero

  myVar = scalarListList( observerPoints.size())

        forAll(observerPoints,pointI)

            {

                myVar[pointI] =  scalarList(Steps.size(),0.0);

            }

}

else

{

  // lengthy calculations resulting in myVar of 

  // same size and type as above

}



// in code / function



if(zoneFaces.size()!=0) // if there are faces of faceZone on processor

{

  // do the calculation which changes values in myVar

}



// Gathering myVar from all processor

    List<List< List<scalar>>> gatheredStuff(Pstream::nProcs());

    gatheredStuff[Pstream::myProcNo()] = myVar;

    Pstream::gatherList(gatheredStuff);



// Further calculation and writing

    if (Pstream::master())

    {

       // add some contents of gatheredStuff

        if(runTime.outputTime())

            {

              // write results to file

            }

     }

So my idea was that the processors which contain the faces from the faceZone compute the values of myVar and the other processors keep their myVar equal to zero and in the gathering/addition the correct result is achieved.

Sadly when I run the code it reaches the Pstream::gatherList comand and then following error message is produced:

Code:

[0] --> FOAM FATAL IO ERROR: 

[0] error in IOstream "IOstream" for operation operator>>(Istream&, List<T>&) : reading first token

[0] 

[0] file: IOstream at line 0.

[0] 

[0]     From function IOstream::fatalCheck(const char*) const

[0]     in file db/IOstreams/IOstreams/IOstream.C at line 114.

[0] 

FOAM parallel run exiting

[0] 

--------------------------------------------------------------------------

MPI_ABORT was invoked on rank 0 in communicator MPI_COMM_WORLD 

with errorcode 1.



NOTE: invoking MPI_ABORT causes Open MPI to kill all MPI processes.

You may or may not see output from other processes, depending on

exactly when Open MPI kills them.

--------------------------------------------------------------------------

--------------------------------------------------------------------------

mpirun has exited due to process rank 0 with PID 16980 on

node waylon-vm exiting without calling "finalize". This may

have caused other processes in the application to be

terminated by signals sent by mpirun (as reported here).

The code runs without any problem if all processors contain faces of the faceZone. Any ideas why this behavior might happen? is there a better way to restrict some calculations just to the processors concernend. Or is there a fundamental misunderstanding in my approach?

Thanks for any input in advance.

Best regards,
Patrick