source: tools/busy.c @ 8ccb0d4

#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>

struct S {
        int i, j, k, l, m, n;
};

void * CallingMalloc( void * arg __attribute__((unused)) ) {
        for ( volatile int i = 0; i < 10000; i += 1 ) {
                volatile int      * ip  = (volatile int      *)malloc( sizeof(   int  ) *   1 );
                volatile int      * aip = (volatile int      *)malloc( sizeof(   int  ) * 100 );
                volatile struct S * sp  = (volatile struct S *)malloc( sizeof(struct S) * 200 );

                sp->i = 0;
                sp->j = 1;
                sp->k = 2;
                sp->l = 3;
                sp->m = 4;
                sp->n = 5;
                for(int j = 0; j < 100; j++) {
                        aip[j] = j;
                }
                *ip = i;

                free( (void*)sp );
                free( (void*)aip );
                free( (void*)ip );
        }
        return NULL;
}

int main(int argc, const char * const argv[]) {
        char * endptr;
        int nThreads = 15;
        switch(argc) {
        case 1:
                break;
        case 2:
                nThreads = strtol(argv[1], &endptr, 10);
                if( *endptr != 0 || nThreads <= 0 ) {
                        fprintf(stderr, "Invalid number of threads %s\n", argv[1]);
                        return 1;
                }
                break;
        default:
                fprintf(stderr, "Usage: %s [no of threads]\n", argv[0]);
                return 1;
        }
        printf("Running %d threads\n", nThreads);
        while(true) {
                pthread_t t[nThreads];
                for(int i = 0; i < nThreads; i++) {
                        pthread_create( &t[i], NULL, CallingMalloc, NULL );
                }

                for(int i = 0; i < nThreads; i++) {
                        pthread_join( t[i], NULL );
                }
        }
        return 0;
}