Comparing io_service::post's performance with GCD's

asio_gcd_perf.cpp

#include <chrono>
#include <iostream>
#include <thread>
#include <dispatch/dispatch.h>
#include <boost/asio.hpp>

using namespace std::chrono_literals;

using std::chrono::duration_cast;
using std::chrono::milliseconds;
using std::chrono::system_clock;
using std::chrono::time_point;

namespace asio = boost::asio;

static auto const amount = 100000000L;

class TimePrinter {
public:
    TimePrinter(std::string const& header) : header_(header), start_(system_clock::now()) {}
    ~TimePrinter()
    {
        auto delta = system_clock::now() - start_;
        std::cout << header_ << ": " << duration_cast<milliseconds>(delta).count() << "ms.\n";
    }

private:
    std::string header_;
    time_point<system_clock> start_;
};

static asio::io_service io;

void asio_testing()
{
    TimePrinter printer{"ASIO"};
    std::thread t{[] {
        asio::io_service::work{io};
        for (auto i = 0l; i < amount; ++i) {
            io.post([] {});
        }
    }};
    io.run();
    t.join();
}

void dispatch_testing()
{
    TimePrinter printer{"GCD"};
    auto sema = dispatch_semaphore_create(0);
    auto queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    for (auto i = 0l; i < amount; ++i) {
        dispatch_async(queue, ^{});
    }
    dispatch_async(queue, ^{ dispatch_semaphore_signal(sema); });
    dispatch_semaphore_wait(sema, DISPATCH_TIME_FOREVER);
}

int main()
{
    asio_testing();
    dispatch_testing();
    return 0;
}