Test for mmapped arena

test.cpp

#include <cstdio>
#include <cstdlib>
#include <omp.h>
const int N = 128;
int
main(void){
  char *buf[N];
#pragma omp parallel for
  for(int i=0;i<N;i++){
    buf[i] = (char*)malloc(128);
  }
  for(int i=0;i<N;i++){
    size_t *p = (size_t*)buf[i];
    if (*(p-1) & 4){
      printf("mmapped arena is used.\n");
      goto label;
    }
  }
label:
  for(int i=0;i<N;i++){
    free(buf[i]);
    buf[i][0] = 0;
  }
}