testing coexistence of pthread and OpenMP

test_threads_omp.cpp

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

#define NTHREADS 4

void *myFun(void *x)
{
  int tid;
  tid = *((int *) x);
  printf("Hi from thread %d!\n", tid);
  #pragma omp parallel
  {
    int n = omp_get_num_threads();
    #pragma omp master
    printf("num threads: %d\n", n);
    #pragma omp for
    for( int i=0; i < n; i++) {
      int t = omp_get_thread_num();
      printf("I'm thread %d-%d!\n", tid, t );
    }
  }
  return NULL;
}

int main(int argc, char *argv[])
{
  pthread_t threads[NTHREADS];
  int thread_args[NTHREADS];
  int rc, i;

  /* spawn the threads */
  for (i=0; i<NTHREADS; ++i)
    {
      thread_args[i] = i;
      printf("spawning thread %d\n", i);
      rc = pthread_create(&threads[i], NULL, myFun, (void *) &thread_args[i]);
    }

  /* wait for threads to finish */
  for (i=0; i<NTHREADS; ++i) {
    rc = pthread_join(threads[i], NULL);
  }

  return 0;
}

Testing Environment: MacOSX ElCapitan

When I use g++-4.9 installed via homebrew, I got SEGV as follows.

spawning thread 0
spawning thread 1
Hi from thread 0!
spawning thread 2
Hi from thread 1!
zsh: segmentation fault  ./a.out

However, if I use g++-5, pthread and OpenMP coexists well.

spawning thread 0
spawning thread 1
Hi from thread 0!
spawning thread 2
Hi from thread 1!
spawning thread 3
Hi from thread 2!
Hi from thread 3!
I'm thread 2-1!
I'm thread 2-2!
num threads: 4
I'm thread 2-3!
I'm thread 0-1!
I'm thread 0-2!
num threads: 4
I'm thread 2-0!
I'm thread 0-3!
I'm thread 1-2!
num threads: 4
I'm thread 1-1!
I'm thread 1-3!
I'm thread 3-2!
I'm thread 3-1!
num threads: 4
I'm thread 3-3!
I'm thread 0-0!
I'm thread 1-0!
I'm thread 3-0!