scatterv.java

MPI for java for Distributed Programming

package mpi.ccl;

/*
 MPI-Java version :
    Sang Lim ([e-mail])
    Northeast Parallel Architectures Center at Syracuse University
    12/2/98
*/

import mpi.*;

public class scatterv {
  static public void main(String[] args) throws MPIException {
  }

  public scatterv() {
  }

  public scatterv(String[] args) throws Exception {
    
    final int MAXLEN = 10;

    int myself,tasks;
    MPI.Init(args);
    myself = MPI.COMM_WORLD.Rank();
    tasks = MPI.COMM_WORLD.Size(); 

    if(tasks > 8) {
      if(myself == 0)
        System.out.println("scatterv must run with less than 8 tasks! ");
      MPI.Finalize();
      return;
    }

    int root,i=0,j,k,stride=15;
    int out[] = new int[tasks*stride];
    int in[]  = new int[MAXLEN];
    int dis[] = new int[MAXLEN];
    int scount[] = new int[MAXLEN];

    
    for(i = 0; i < MAXLEN;i++){
       dis[i] = i*stride;
       scount[i] = 5;
       in[i] = 0;
    }
    scount[0] = 10;
    
    for (i = 0;i < tasks*stride;i++)
       out[i] = i;
    
    MPI.COMM_WORLD.Scatterv(out,0,scount,dis,MPI.INT,in,0,scount[myself],MPI.INT,0);

    String [] messbuf = new String [1] ;

    if(myself==0){
       System.out.println("Original array on root...");
       for(i=0; i<tasks*stride; i++)
          System.out.print(out[i]+" ");
       System.out.println();
       System.out.println();

       System.out.println("Result on proc 0...");
       System.out.println("Stride = 15 "+"Count = "+scount[0]);
       for(i=0; i<MAXLEN; i++)
          System.out.print(in[i]+" ");
       System.out.println();
       System.out.println();

       // Reproduces output of original test case, but deterministically

       int nmess = tasks < 3 ? tasks : 3 ;
       for(int t = 1 ; t < nmess ; t++) {
           MPI.COMM_WORLD.Recv(messbuf, 0, 1, MPI.OBJECT, t, 0) ;

           System.out.print(messbuf [0]) ;
       }
    }
    
    if(myself==1){
        StringBuffer mess = new StringBuffer() ;

        mess.append("Result on proc 1...\n");
	mess.append("Stride = 15 "+"Count = "+scount[1] + "\n");
	for(i=0; i<MAXLEN; i++)
	    mess.append(in[i]+" ");
	mess.append("\n");
	mess.append("\n");

        messbuf [0] = mess.toString() ;
        MPI.COMM_WORLD.Send(messbuf, 0, 1, MPI.OBJECT, 0, 0) ;
    }

    if(myself==2){
        StringBuffer mess = new StringBuffer() ;

        mess.append("Result on proc 2...\n");
        mess.append("Stride = 15 "+"Count = "+scount[2] + "\n");
        for(i=0; i<MAXLEN; i++)
           mess.append(in[i]+" ");
	mess.append("\n");

        messbuf [0] = mess.toString() ;
        MPI.COMM_WORLD.Send(messbuf, 0, 1, MPI.OBJECT, 0, 0) ;
    }

    if(myself == 0)  System.out.println("Scatterv TEST COMPLETE");
    MPI.Finalize();
  }
}

// Things to do
//
//   Make output deterministic by gathering and printing from root.