Is xio_mempool thread safe? about accelio HOT 6 CLOSED

#include <libxio.h>
#include <pthread.h>
#include <stdlib.h>
#include <time.h>
#include <assert.h>

const  size_t thread_cnt = 10;
const  size_t alloc_size_limit=256;
const  size_t iteration_cnt = 100000;

void * test_mempool(void* pool_) {
  struct xio_mempool* mempool = (struct xio_mempool*)(pool_);
  size_t i;
  size_t alloc_size;
  int retv;
  struct xio_reg_mem obj;

  for(i=0; i<iteration_cnt; ++i) {
    alloc_size = rand() % alloc_size_limit +1;
    retv = xio_mempool_alloc(mempool, alloc_size, &obj);
    assert(retv == 0);
    *(char *)(obj.addr) = '1';
    xio_mempool_free(&obj);
  }

  return NULL;
}


int main(){
  size_t i;
  struct xio_mempool* mempool;
  pthread_t threads[thread_cnt];
  void* status;
  srand(time(0));
  xio_init();

  mempool = xio_mempool_create(-1, 
    XIO_MEMPOOL_FLAG_REG_MR|XIO_MEMPOOL_FLAG_USE_SMALLEST_SLAB);

  xio_mempool_add_slab(mempool, alloc_size_limit*1.2d, 1, 1<<30, 1, 0);


  for (i=0; i<thread_cnt; ++i) {
    pthread_create(&threads[i], NULL, test_mempool, mempool);
  }

  for (i=0; i<thread_cnt; ++i) {
    pthread_join(threads[i], &status);
  }

  xio_shutdown();
  return 0;
}