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Subject: [OMPI users] Error on sending argv
From: Andrew Wiles (awiles.tv_at_[hidden])
Date: 2010-04-19 12:31:02

Hi all Open MPI users,

I write a simple MPI program to send a text message to another process. The
code is below.


#include "mpi.h"

#include <stdio.h>

#include <stdlib.h>

#include <string.h>


int main(int argc, char* argv[]) {

    int dest, noProcesses, processId;

    MPI_Status status;


    char* buffer;


    char* text = "ABCDEF";


    MPI_Init(&argc, &argv);

    MPI_Comm_size(MPI_COMM_WORLD, &noProcesses);

    MPI_Comm_rank(MPI_COMM_WORLD, &processId);


    buffer = (char*) malloc(256 * sizeof(char));


    if (processId == 0) {

      fprintf(stdout, "Master: sending %s to %d\n", text, 1);

      MPI_Send((void *)&text, strlen(text) + 1, MPI_CHAR, 1, 0,

    } else {

      MPI_Recv(&buffer, 128, MPI_CHAR, MPI_ANY_SOURCE, MPI_ANY_TAG,
MPI_COMM_WORLD, &status);

      fprintf(stdout, "Slave: received %s from %d\n", buffer,



    return 0;


After compiling and executing it I get the following output:

[root_at_cluster Desktop]# mpicc -o test test.c

[root_at_cluster Desktop]# mpirun -np 2 test

Master: sending ABCDEF to 1

Slave: received ABCDEF from 0


In the source code above, I replace

char* text = "ABCDEF";


char* text = argv[1];

then compile and execute it again with the following commands:

[root_at_cluster Desktop]# mpicc -o test test.c

[root_at_cluster Desktop]# mpirun -np 2 test ABCDEF

Then I get the following output:

Master: sending ABCDEF to 1

[cluster:03917] *** Process received signal ***

[cluster:03917] Signal: Segmentation fault (11)

[cluster:03917] Signal code: Address not mapped (1)

[cluster:03917] Failing at address: 0xbfa445a2

[cluster:03917] [ 0] [0x959440]

[cluster:03917] [ 1] /lib/ [0x76be02]

[cluster:03917] [ 2] test(main+0x143) [0x80488b7]

[cluster:03917] [ 3] /lib/ [0x73be8c]

[cluster:03917] [ 4] test [0x80486c1]

[cluster:03917] *** End of error message ***


mpirun noticed that process rank 1 with PID 3917 on node
exited on signal 11 (Segmentation fault).


I'm very confused because the only difference between the two source codes
is the difference between

char* text = "ABCDEF";


char* text = argv[1];

Can any one help me why the results are so different? How can I send argv[i]
to another process?

Thank you very much!