Simple Boost ASIO based parallelization template

par.cpp

#include <iostream>
#include <string>
#include <boost/thread.hpp>
#include <boost/asio.hpp>

#define N_THREADS 4
#define N_JOBS 10

/* compile on Ubuntu using
g++ par.cpp -lboost_thread -lboost_system
must have installed libboost-dev libboost-thread-dev
*/

// simple task callback
void print_task(int n) {
  std::cout << "job " << n << " running" << std::endl;
}

int main(int argc, char **argv) {
  // create io service
  boost::asio::io_service io_service;
  // use the work object to keep threads alive before jobs are posted
  std::auto_ptr<boost::asio::io_service::work> work(new boost::asio::io_service::work(io_service));
  // create and populate the thread pool with worker threads
  boost::thread_group workers;
  for(int i = 0; i < N_THREADS; i++) {
    workers.create_thread(boost::bind(&boost::asio::io_service::run, &io_service));
  }
  std::cout << "queueing jobs" << std::endl;
  // now post jobs
  for(int i = 0; i < N_JOBS; i++) {
    io_service.post(boost::bind(print_task, i));
    std::cout << "queued job " << i << std::endl;
  }
  // destroy the work object to indicate that there are no more jobs
  work.reset();
  // now wait for all running jobs to complete
  workers.join_all();
  // at this point all work is done
  std::cout << "all jobs complete" << std::endl;
}