MPI_Comm_create(3OpenMPI)MPI_Comm_create(3OpenMPI)NAMEMPI_Comm_create - Creates a new communicator.
SYNTAXC Syntax
#include <mpi.h>
int MPI_Comm_create(MPI_Comm comm, MPI_Group group, MPI_Comm *newcomm)
Fortran Syntax
INCLUDE 'mpif.h'
MPI_COMM_CREATE(COMM, GROUP, NEWCOMM, IERROR)
INTEGER COMM, GROUP, NEW, IERROR
C++ Syntax
#include <mpi.h>
MPI::Intercomm MPI::Intercomm::Create(const Group& group) const
MPI::Intracomm MPI::Intracomm::Create(const Group& group) const
INPUT PARAMETER
comm Communicator (handle).
group Group, which is a subset of the group of comm (handle).
OUTPUT PARAMETERS
newcomm New communicator (handle).
IERROR Fortran only: Error status (integer).
DESCRIPTION
This function creates a new communicator newcomm with communication
group defined by group and a new context. The function sets newcomm to
a new communicator that spans all the processes that are in the group.
It sets newcomm to MPI_COMM_NULL for processes that are not in the
group. The call is erroneous if not all group arguments have the same
value, or if group is not a subset of the group associated with comm.
Note that the call must be executed by all processes in comm, even if
they do not belong to the new group.
NOTESMPI_Comm_create provides a means of making a subset of processes for
the purpose of separate MIMD computation, with separate communication
space. newcomm, which is created by MPI_Comm_create, can be used in
subsequent calls to MPI_Comm_create (or other communicator construc‐
tors) to further subdivide a computation into parallel sub-computa‐
tions. A more general service is provided by MPI_Comm_split.
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_Comm_split
MPI_Intercomm_create
Open MPI 1.2 September 2006 MPI_Comm_create(3OpenMPI)
