Tutorial: Running MPI Programs on Hadoop Cluster

--D. Thiebaut (talk) 13:57, 15 October 2013 (EDT)
Revised: --D. Thiebaut (talk) 12:02, 15 March 2017 (EDT)

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Setup Password-Less ssh to the Hadoop cluster

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Setup Aliases

• This section is not required, but will save you a lot of typing.
• Edit your .bashrc file

 emacs ~/.bashrc -nw

• and add these 3 lines at the end, where you will replace yourusername by your actual user name.

alias hadoop02='ssh -Y yourusername@hadoop02.dyndns.org'
alias hadoop03='ssh -Y yourusername@hadoop03.dyndns.org'
alias hadoop04='ssh -Y yourusername@hadoop04.dyndns.org'

• Then tell bash to re-read this setup file, since we just modified it. This way bash will learn the 3 new aliases we've defined.

source ~/.bashrc

• Now just connect to the servers using their name only:

hadoop02
hadoop03
hadoop04

Test MPI

MPI should already be installed, and your account ready to access it. To verify this, create a simple MPI "Hello World!" program, compile it, and run it.

/* C Example */
#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;
}

• Compile and Run

mpicc -o hello helloWorld.c
mpirun -np 2 ./hello
Hello world from process 0 of 2
Hello world from process 1 of 2

• If you see the two lines starting with "Hello world" on your screen, MPI was successfully installed on your system!

Configuration for Running On Multiple Servers

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