#include <boost/thread.hpp>
#include <boost/chrono.hpp>
#include <boost/thread/barrier.hpp>
#include <iostream>
#include <cstdlib>
#include <ctime>
using namespace std;
void worker(int id, boost::barrier &sync_point) {
        cout << "thread :" << id << "entering work" << endl;
        boost::this_thread::sleep_for(boost::chrono::milliseconds(5000));
        sync_point.wait();
        cout << "thread:" << id << "leaving barrier" << endl;
}

int main() {
        srand(time(0));
        int num_threads=rand()%6+3;
        cout << " Creating:" << num_threads << endl;
        boost::barrier sync_point(num_threads);

        boost::thread_group tg;
        for (int i=0;i<num_threads;i++) {
                tg.create_thread(boost::bind(worker,i,boost::ref(sync_point)));
        }
        tg.join_all();
        return 0;
}