Dumb program to just allocate some memory in each thread using OpenMP

omp_glom.c

#include <omp.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <math.h>

#define K          1024l
#define MEG     1048576l
#define GIG  1073741824l

/***
**** Allocate some chunk of memory in each thread
***/

int 
main (int argc, char *argv[]) 
{
  size_t i, j;
  const size_t blobsize = 512 * MEG;

/*** Start of parallel region ***/
#pragma omp parallel private(i, j)
  {
    /* sizeof(double) = 8 => allocate 4 GB per thread */
    double *blob = (double*)NULL;
    if ((double*)NULL == (blob = (double*)calloc(blobsize, sizeof(double))))
      {
        fprintf(stderr, "Error allocating blob in thread %d\n", omp_get_thread_num());
        exit(1);
      }

    for (i = 0; i < 250; ++i)
      {
      for (j = 0; j < blobsize; ++j)
        {
          blob[j] = (double)j * (double)sqrt((double)j);
        }
      }

    for (i = 0; i < 32; ++i)
      {
        printf("blob[%ld] = %g\n", i, blob[i]);
      }

    free(blob);
  } 
/*** End of parallel region ***/

sleep(90);
printf ("Done.\n");

return 0;
}