text: // Copyright 2011 The University of Michigan
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //     http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  //
  // Authors - Jie Yu (jieyu@umich.edu)
  
  #include <cassert>
  #include <cstdio>
  #include <cstdlib>
  #include <pthread.h>
  
  #define NUM_THREADS 2
  
  int counter = 0;
  
  void *thread(void *arg) {
    __sync_fetch_and_add(&counter, 1);
    return NULL;
  }
  
  int main(int argc, char *argv[]) {
    pthread_t tids[NUM_THREADS];
    __sync_fetch_and_add(&counter, 1);
    for (int i = 0; i < NUM_THREADS; i++) {
      pthread_create(&tids[i], NULL, thread, NULL);
    }
    for (int i = 0; i < NUM_THREADS; i++) {
      pthread_join(tids[i], NULL);
    }
    __sync_fetch_and_add(&counter, 1);
    return 0;
  }
  
  