omp_bug4.c

/******************************************************************************
 * FILE: omp_bug4.c
 * DESCRIPTION:
 *   This very simple program causes a segmentation fault.
 * AUTHOR: Blaise Barney  01/09/04
 * LAST REVISED: 04/06/05
 ******************************************************************************/
#include <omp.h>
#include <stdio.h>
#include <stdlib.h>
#define N 1048

int main (int argc, char *argv[]) 
{
  int nthreads, tid, i, j;
  double a[N][N];

  /* Fork a team of threads with explicit variable scoping */
#pragma omp parallel shared(nthreads) private(i,j,tid,a)
  {

    /* Obtain/print thread info */
    tid = omp_get_thread_num();
    if (tid == 0) 
    {
      nthreads = omp_get_num_threads();
      printf("Number of threads = %d\n", nthreads);
    }
    printf("Thread %d starting...\n", tid);

    /* Each thread works on its own private copy of the array */
    for (i=0; i<N; i++)
      for (j=0; j<N; j++)
        a[i][j] = tid + i + j;

    /* For confirmation */
    printf("Thread %d done. Last element= %f\n",tid,a[N-1][N-1]);

  }  /* All threads join master thread and disband */

}