Definition
MPI_Group_size gets the number of MPI processes in the group given.
int MPI_Group_size(MPI_Group group,
int* size);
Topology
C | Fortran-2008 | Fortran-90
MPI_Group_size
Parameters
- group
The MPI group to explore.
- size
A pointer on the variable in which write the size of the MPI group given.
Return value
The error code returned from the group size retrieval.
- MPI_SUCCESS: the routine successfully completed.
Example
#include <stdio.h>
#include <stdlib.h>
#include <mpi.h>
/**
* @brief Display the number of MPI processes in the group of the default
* communicator MPI_COMM_WORLD.
* @details This code obtains the group from the default communicator, then
* queries that group to know how many processes are part of it.
**/
int main(int argc, char* argv[])
{
MPI_Init(&argc, &argv);
// Get the group from the default communicator
MPI_Group group;
MPI_Comm_group(MPI_COMM_WORLD, &group);
// Get the size of the group
int size;
MPI_Group_size(group, &size);
// Each process prints the number of processes in that group
printf("We are %d MPI processes in the group of the default communicator MPI_COMM_WORLD.\n", size);
MPI_Finalize();
return EXIT_SUCCESS;
}