:ref:`MPI_Session_get_num_psets` |mdash| Query runtime for number of available process sets
#include <mpi.h>
int MPI_Session_get_num_psets(MPI_Session session, MPI_Info info, int *npset_names)
USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_SESSION_GET_NUM_PSETS(SESSION, INFO, NPSET_NAMES, IERROR)
INTEGER SESSION, INFO, SESSION, IERROR
USE mpi_f08
MPI_Session_get_num_psets(session, info, npset_names, ierror)
TYPE(MPI_Session), INTENT(IN) :: session
TYPE(MPI_Info), INTENT(IN) :: info
INTEGER, INTENT(OUT) :: npset_names
INTEGER, OPTIONAL, INTENT(OUT) :: ierror
session
: session (handle)info
: info object (handle)
npset_names
: number of available process sets (non-negtive integer)ierror
: Fortran only: Error status (integer).
:ref:`MPI_Session_get_num_psets` is used to query the runtime for the number of available process sets in which the calling MPI process is a member. An MPI implementation is allowed to increase the number of available process sets during the execution of an MPI application when new process sets become available. However, MPI implementations are not allowed to change the index of a particular process set name, or to change the name of the process set at a particular index, or to delete a process set name once it has been added.
When a process set becomes invalid, for example, when some processes become unreachable due to failures in the communication system, subsequent usage of the process set name may raise an error. For example, creating an MPI_Group from such a process set might succeed because it is a local operation, but creating an MPI_Comm from that group and attempting collective communication may raise an error.
.. seealso:: :ref:`MPI_Session_init`