MPI Hello World

hello.c

// Hello World MPI C program from Lecture 3, slide 31

#include <stdio.h>
#include <mpi.h>

int main(argc, argv)
int argc;
char *argv[];
{
    int rank, size;
    MPI_Init(&argc, &argv); // starts MPI
    MPI_Comm_rank(MPI_COMM_WORLD, &rank); // get current process id
    MPI_Comm_size(MPI_COMM_WORLD, &size); // get number of processes

    printf("Hello world from process %d of %d\n", rank, size);
    MPI_Finalize();
    return 0;
}

// To compile
//module load OpenMPI/1.10.0-GCC-4.9.2
//mpicc -o hello hello.c

// To run (see jobc.sh)
//module load OpenMPI/1.10.0-GCC-4.9.2
//mpirun hello

hello.py

from mpi4py import MPI

size = MPI.COMM_WORLD.Get_size()
rank = MPI.COMM_WORLD.Get_rank()

print("Hello World! I am process %d of %d.\n" % (rank, size))

job.sh

#!/bin/bash

#SBATCH --account=comp90024
#SBATCH --job-name=HelloJob
#SBATCH -p cloud
#SBATCH --time=00:01:00
#SBATCH --nodes=1
#SBATCH --ntasks=8
#SBATCH --cpus-per-task=1

echo 'HelloJob'

echo ' '

module load Python/3.6.4-intel-2017.u2

echo 'Python Path: '
which python

echo ' '

mpirun python hello.py

jobc.sh

#!/bin/bash

#SBATCH --account=comp90024
#SBATCH --job-name=HelloJobC
#SBATCH -p cloud
#SBATCH --time=00:01:00
#SBATCH --nodes=1
#SBATCH --ntasks=8
#SBATCH --cpus-per-task=1

echo 'HelloJobC'

echo ' '

# This job script is for hello.c program.
# You should compile it first, see hello.c note.

module load OpenMPI/1.10.0-GCC-4.9.2
mpirun hello