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MPI_Barrier(3OpenMPI)                                                                  MPI_Barrier(3OpenMPI)



NAME
       MPI_Barrier - Blocks until all processes have reached this routine.


SYNTAX
C Syntax
       #include <mpi.h>
       int MPI_Barrier(MPI_Comm comm)


Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_BARRIER(COMM, IERROR)
            INTEGER   COMM, IERROR


C++ Syntax
       #include <mpi.h>
       void MPI::Comm::Barrier() const = 0


INPUT PARAMETER
       comm      Communicator (handle).


OUTPUT PARAMETER
       IERROR    Fortran only: Error status (integer).


DESCRIPTION
       Blocks  the caller until all group members have called it; the call returns at any process only after
       all group members have entered the call.


WHEN COMMUNICATOR IS AN INTER-COMMUNICATOR
       When the communicator is an inter-communicator, the barrier operation is performed  across  all  pro-cesses processes
       cesses  in  both groups.  All processes in the first group may exit the barrier when all processes in
       the second group have entered the barrier.


ERRORS
       Almost all MPI routines return an error value; C routines as the value of the  function  and  Fortran
       routines  in  the  last argument. C++ functions do not return errors. If the default error handler is
       set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to  throw
       an MPI:Exception object.

       Before  the  error value is returned, the current MPI error handler is called. By default, this error
       handler aborts the MPI job, except for I/O function errors. The error handler  may  be  changed  with
       MPI_Comm_set_errhandler;  the  predefined  error handler MPI_ERRORS_RETURN may be used to cause error
       values to be returned. Note that MPI does not guarantee that an MPI  program  can  continue  past  an
       error.


SEE ALSO
       MPI_Bcast



Open MPI 1.2                                   September 2006                          MPI_Barrier(3OpenMPI)