我的应用程序使用libhiredis和libev后端。我需要发送redis async命令并处理结果redis async回调。但是，与这里的简单示例不同，我不能使用默认的事件循环。下面的代码使用一个自定义事件循环来近似该示例。但是，当只使用 redisLibevAttach() 引发libev io watcher，事件循环线程立即终止。你可以通过跑步看到这一点

g++ -g -std=c++11 -Wall -Wextra -Werror hiredis_ev.cpp -o hiredis_ev -lpthread -lhiredis -lev && gdb ./hiredis_ev

gdb愉快地打印出一个新线程被创建并几乎立即终止。通过运行进一步证实了这一点 info thread 在gdb中不显示 my_ev_loop . 但是，如果我修改代码来添加其他libev观察者，比如计时器，那么一切都很好。你可以通过跑步看到这一点

g++ -g -DTIMER -std=c++11 -Wall -Wextra -Werror hiredis_ev.cpp -o hiredis_ev -lpthread -lhiredis -lev &&  ./hiredis_ev

我不需要一个虚拟libev计时器来保持事件循环运行。我错过了什么？

# include <iostream>
# include <thread>
# include <hiredis/hiredis.h>
# include <hiredis/async.h>
# include <hiredis/adapters/libev.h>
static struct ev_loop *loop = nullptr;
static void redis_async_cb(redisAsyncContext *, void *, void *)
{
  std::cout << "Redis async callback" << std::endl;
  fflush(nullptr);
}
# ifdef TIMER
  static ev_timer timer_w;
  static void ev_timer_cb(EV_P_ ev_timer *, int)
  {
    std::cout << "EV timer callback" << std::endl;
    fflush(nullptr);
  }
# endif
int main()
{
  loop = ev_loop_new(EVFLAG_AUTO);
# ifdef TIMER
  ev_timer_init(&timer_w, ev_timer_cb, 0, 0.1);
  ev_timer_start(loop, &timer_w);
# endif
  redisAsyncContext* async_context = redisAsyncConnect("localhost", 6379);
  if (nullptr == async_context)
  {
    throw std::runtime_error("No redis async context");
  }
  redisLibevAttach(loop, async_context);
  std::thread ev_thread(ev_run, loop, 0); 
  pthread_setname_np(ev_thread.native_handle(), "my_ev_loop");
  ev_thread.detach();
  // Give the event loop time to start
  while (!ev_iteration(loop))
  {
    std::this_thread::sleep_for(std::chrono::milliseconds(1));
  }
  // Send a SUBSCRIBE message which should generate an async callback
  if (REDIS_OK != redisAsyncCommand(async_context, redis_async_cb, nullptr, "SUBSCRIBE foo"))
  {
    throw std::runtime_error("Could not issue redis async command");
  }
  std::cout << "Waiting for async callback" << std::endl;
  fflush(nullptr);
    fflush(nullptr);
  // Wait forever (use CTRL-C to terminate)
  while (true)
  {
    std::this_thread::sleep_for(std::chrono::milliseconds(1));
  }
  return 0;
}