c++ thread pool example(linux only)

thread_pool.cpp

#include <boost/shared_ptr.hpp>
#include <boost/make_shared.hpp>
#include <boost/thread.hpp>
#include <boost/bind.hpp>
#include <boost/asio.hpp>
#include <boost/move/move.hpp>
#include <iostream>
#include <unistd.h>

namespace asio = boost::asio; 

int sleep_print(int seconds) {
	std::cout << "goint to sleep (" << seconds << ")" << std::endl;
	sleep(seconds);
	std::cout << "wake up (" << seconds << ")" << std::endl;
	return 0;
}


typedef boost::packaged_task<int> task_t;
typedef boost::shared_ptr<task_t> ptask_t;


void push_job(int seconds, boost::asio::io_service& io_service, std::vector<boost::shared_future<int> >& pending_data) {
	ptask_t task = boost::make_shared<task_t>(boost::bind(&sleep_print, seconds));
	boost::shared_future<int> fut(task->get_future());
	pending_data.push_back(fut);
	io_service.post(boost::bind(&task_t::operator(), task));
}


int main() {

	boost::asio::io_service io_service;
	boost::thread_group threads;
	boost::asio::io_service::work work(io_service);
	for (int i = 0; i < boost::thread::hardware_concurrency() ; ++i)
	{
		threads.create_thread(boost::bind(&boost::asio::io_service::run,
			&io_service));
	}
	std::vector<boost::shared_future<int> > pending_data; // vector of futures

	sleep_print(2);
	push_job(3, io_service, pending_data);
	push_job(4, io_service, pending_data);

//	boost::thread task(boost::move(pt)); // launch task on a thread

	boost::wait_for_all(pending_data.begin(), pending_data.end());

	push_job(3, io_service, pending_data);
	push_job(4, io_service, pending_data);
	push_job(5, io_service, pending_data);
	boost::wait_for_all(pending_data.begin(), pending_data.end());
	
	return 0;
}