NAME¶
MPI_Intercomm_merge - Creates an intracommuncator from an intercommunicator
SYNOPSIS¶
int MPI_Intercomm_merge(MPI_Comm intercomm, int high, MPI_Comm *newintracomm)
- intercomm
- - Intercommunicator (handle)
- high
- - Used to order the groups within comm (logical) when creating the new
communicator. This is a boolean value; the group that sets high true has
its processes ordered after the group that sets this value to
false. If all processes in the intercommunicator provide the same value,
the choice of which group is ordered first is arbitrary.
OUTPUT PARAMETERS¶
- newintracomm
- - Created intracommunicator (handle)
NOTES¶
While all processes may provide the same value for the
high parameter,
this requires the MPI implementation to determine which group of processes
should be ranked first.
THREAD AND INTERRUPT SAFETY¶
This routine is thread-safe. This means that this routine may be safely used by
multiple threads without the need for any user-provided thread locks. However,
the routine is not interrupt safe. Typically, this is due to the use of memory
allocation routines such as
malloc or other non-MPICH runtime routines
that are themselves not interrupt-safe.
NOTES FOR FORTRAN¶
All MPI routines in Fortran (except for
MPI_WTIME and
MPI_WTICK )
have an additional argument
ierr at the end of the argument list.
ierr is an integer and has the same meaning as the return value of the
routine in C. In Fortran, MPI routines are subroutines, and are invoked with
the
call statement.
All MPI objects (e.g.,
MPI_Datatype ,
MPI_Comm ) are of type
INTEGER in Fortran.
ALGORITHM¶
b Allocate contexts Local and remote group leaders swap high values Determine
the high value. Merge the two groups and make the intra-communicator e
ERRORS¶
All MPI routines (except
MPI_Wtime and
MPI_Wtick ) return an error
value; C routines as the value of the function and Fortran routines in the
last argument. Before the value is returned, the current MPI error handler is
called. By default, this error handler aborts the MPI job. The error handler
may be changed with
MPI_Comm_set_errhandler (for communicators),
MPI_File_set_errhandler (for files), and
MPI_Win_set_errhandler
(for RMA windows). The MPI-1 routine
MPI_Errhandler_set may be used but
its use is deprecated. The predefined error handler
MPI_ERRORS_RETURN
may be used to cause error values to be returned. Note that MPI does
not guarentee that an MPI program can continue past an error; however,
MPI implementations will attempt to continue whenever possible.
- MPI_SUCCESS
- - No error; MPI routine completed successfully.
- MPI_ERR_COMM
- - Invalid communicator. A common error is to use a null communicator in a
call (not even allowed in MPI_Comm_rank ).
- MPI_ERR_INTERN
- - This error is returned when some part of the MPICH implementation is
unable to acquire memory.
SEE ALSO¶
MPI_Intercomm_create, MPI_Comm_free
LOCATION¶
/tmp/gyCYfBi4J6/mpich-3.1/src/mpi/comm/intercomm_merge.c