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++ 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

1.6.5                                             Jun 26, 2013                                    MPI_Barrier(3)