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 processes 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++ func-
       tions 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)