[Trilinos-Users] Epetra_MpiComm.Barrier() does not seem to work?

[Matt G]

If you add the time (and other information) into the print statements, you
will see that it is out of order, but properly serial in actual execution.
 There is a simple way to do that through most mpirun commands, but the
syntax depends on the flavor you are running.

Enjoy
--Matthew Goodman

=====================
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On Sat, Jun 25, 2011 at 10:03 AM, Heroux, Mike <MHeroux at csbsju.edu> wrote:

> Jack,
>
> Generally speaking, output does not respect communication barriers.  There
> are functions in Teuchos that serialize output, and might do what you want.
> Another approach is to send all output to a single process that is in
> charge
> of output.  However, these approaches are not scalable, so you need to be
> careful.
>
> I hope this helps.
>
> Mike
>
>
> On 6/24/11 2:25 PM, "Jack Chessa" <jfchessa at utep.edu> wrote:
>
> > Hello,  I am having issues (I believe) with the
> > Epetra_MpiComm.Barrier() member.  When I execute the following code
> > with three processors
> >
> > #ifdef HAVE_MPI
> > #include "mpi.h"
> > #include "Epetra_MpiComm.h"
> > #else
> > #include "Epetra_SerialComm.h"
> > #endif
> >
> >
> > int main(int argc, char* argv[])
> > {
> >
> > #ifdef HAVE_MPI
> > MPI_Init(&argc, &argv);
> > Epetra_MpiComm MyComm(MPI_COMM_WORLD);
> > #else
> > Epetra_SerialComm MyComm;
> > #endif
> >
> > if ( MyComm.MyPID()==0 )
> > std::cout << "\nHi there from processor " << MyComm.MyPID() << endl;
> >
> > if ( MyComm.MyPID()==1 )
> > std::cout << "\nHi there from processor " << MyComm.MyPID() << endl;
> >
> > if ( MyComm.MyPID()==2 )
> > std::cout << "\nHi there from processor " << MyComm.MyPID() << endl;
> >
> >
> >
> > MyComm.Barrier();
> >
> > if ( MyComm.MyPID()==0 )
> > std::cout << "\nfrom processor " << MyComm.MyPID() << endl;
> >
> > MyComm.Barrier();
> >
> > if ( MyComm.MyPID()==1 )
> > std::cout << "\nfrom processor " << MyComm.MyPID() << endl;
> >
> > MyComm.Barrier();
> >
> > if ( MyComm.MyPID()==2 )
> > std::cout << "\nfrom processor " << MyComm.MyPID() << endl;
> >
> > return 0;
> > }
> >
> > //------------------
> > I tend to get something as follows; that seems to indicate that the
> > barrier is being ignored.  Is there some trick I am missing?
> >
> > [jfchessa at virgo2 examples]$ mpirun -np 3 barrier_test
> >
> > Hi there from processor 1
> >
> > Hi there from processor 2
> >
> > Hi there from processor 0
> >
> > from processor 1
> >
> > from processor 2
> >
> > from processor 0
> >
> > Thanks for any information
> > Jack
> >
> >
> > Jack Chessa
> > Associate Professor
> > Mechancial Engineering
> > The University of Texas at El Paso
> > Voice: (915) 747-6900
> > Fax: (915) 747-5019
> > Email: jfchessa at utep.edu
> >
> >
> >
> >
> > _______________________________________________
> > Trilinos-Users mailing list
> > Trilinos-Users at software.sandia.gov
> > http://software.sandia.gov/mailman/listinfo/trilinos-users
> >
>
>
>
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