posix thread synchronization stop at same code

Question

I have multiple threads, and I want each thread to wait for every others to complete at certain point in the code before proceeding as following:

void *run() { 
  for (i=0;i<1000;i++){
    do_1st();
    // sync() all stop here wait for all then resume
    do_2nd();
  }
}

I tried to use pthread_cond_wait.. but It seems very complicated.

Is there any easy wait to do this ?

Thank you

Answer 1

You can use a pthread_barrier, initialize it before you start your threads, and set the count to the no. of threads that's running your loop. e.g. if you have 8 threads:

pthread_barrier_init(&my_barrier,NULL,8);

The thread loop now becomes

void *run() { 
  for (i=0;i<1000;i++){
    do_1st();
    pthread_barrier_wait(&my_barrier);
    do_2nd();
  }
}