static void worker(void* arg) {
  struct uv__work* w;
  QUEUE* q;

  (void) arg;

  for (;;) {
    uv_mutex_lock(&mutex);

    while (QUEUE_EMPTY(&wq))
      uv_cond_wait(&cond, &mutex);

    q = QUEUE_HEAD(&wq);

    if (q == &exit_message)
      uv_cond_signal(&cond);
    else {
      QUEUE_REMOVE(q);
      QUEUE_INIT(q);  /* Signal uv_cancel() that the work req is
                             executing. */
    }

    uv_mutex_unlock(&mutex);

    if (q == &exit_message)
      break;

    w = QUEUE_DATA(q, struct uv__work, wq);
    w->work(w);

    uv_mutex_lock(&w->loop->wq_mutex);
    w->work = NULL;  /* Signal uv_cancel() that the work req is done
                        executing. */
    QUEUE_INSERT_TAIL(&w->loop->wq, &w->wq);
    uv_async_send(&w->loop->wq_async);
    uv_mutex_unlock(&w->loop->wq_mutex);
  }
}

#include <thread>
#include <functional>
#include <boost/asio.hpp>

int main ( int argc, char* argv[] ) {
    asio::io_service io_service;
    asio::io_service::work work(io_service);

    std::vector<std::thread> threadPool;

    for(size_t t = 0; t < std::thread::hardware_concurrency(); t++){
        threadPool.push_back(thread(std::bind(&asio::io_service::run, &io_service)));
    }

    io_service.post(std::bind(an_expensive_calculation, 42));
    io_service.post(std::bind(a_long_running_task, 123));

    //Do some things with the main thread

    io_service.stop();
    for(std::thread& t : threadPool) {
        t.join();
    }
}

//
// memcached.c
//
typedef struct {
    pthread_t thread_id;        /* unique ID of this thread */
    struct event_base *base;    /* libevent handle this thread uses */
    struct event notify_event;  /* listen event for notify pipe */
    int notify_receive_fd;      /* receiving end of notify pipe */
    int notify_send_fd;         /* sending end of notify pipe */
    struct thread_stats stats;  /* Stats generated by this thread */
    struct conn_queue *new_conn_queue; /* queue of new connections to handle */
    cache_t *suffix_cache;      /* suffix cache */
    uint8_t item_lock_type;     /* use fine-grained or global item lock */
} LIBEVENT_THREAD;

//
// thread.c
//
void thread_init(int nthreads, struct event_base *main_base) {
//
// 中略
//
    threads = calloc(nthreads, sizeof(LIBEVENT_THREAD));
//
// さらに中略
//
    for (i = 0; i < nthreads; i++) {
        int fds[2];
        if (pipe(fds)) {
            perror("Can't create notify pipe");
            exit(1);
        }

        threads[i].notify_receive_fd = fds[0];
        threads[i].notify_send_fd = fds[1];

        setup_thread(&threads[i]);
        /* Reserve three fds for the libevent base, and two for the pipe */
        stats.reserved_fds += 5;
    }

    /* Create threads after we've done all the libevent setup. */
    for (i = 0; i < nthreads; i++) {
        create_worker(worker_libevent, &threads[i]);
    }

    /* Wait for all the threads to set themselves up before returning. */
    pthread_mutex_lock(&init_lock);
    wait_for_thread_registration(nthreads);
    pthread_mutex_unlock(&init_lock);
}

#define lll_futex_wait(futex, val, private) \
  lll_futex_timed_wait(futex, val, NULL, private)

#define lll_futex_timed_wait(futex, val, timeout, private) \
  ({                                         \
    register const struct timespec *__to __asm ("r10") = timeout;          \
    int __status;                                \
    register __typeof (val) _val __asm ("edx") = (val);                \
    __asm __volatile ("syscall"                            \
             : "=a" (__status)                         \
             : "0" (SYS_futex), "D" (futex),                 \
           "S" (__lll_private_flag (FUTEX_WAIT, private)),         \
           "d" (_val), "r" (__to)                    \
             : "memory", "cc", "r11", "cx");                 \
    __status;                                    \
  })

futex(futex, FUTEX_WAIT, val, timeout, NULL, 0);  // 便宜上、上記コードの引数の変数名をそのままつかっているが、
                                                  // 1つめのfutexはシステムコールのfutexで、
                                                  // 2つめは引数のpthread_cond_tの__futexメンバ変数のアドレス