Re: [Libevent-users] Event loop not exiting when freeing bufferevent

[Bas Verhoeven <libevent@xxxxxxxxxx>]

Nick Mathewson wrote:
> It's supposed to work like that, yes. My guess would be that either
> there's a bug in your code, or that you've found a bug in Libevent.
>
> To narrow it down, can you write a short test program that displays
> the problematic behavior?  I've tried to do one myself, but I can't
> get the behavior you're seeing: for me, disabling the last bufferevent
> does indeed exit the loop.
>   
Hi, thanks for your response.

I guess I was wrong - this isn't related to bufferevents at all. I've 
written a small application that simply initializes libevent & evdns and 
starts the loop:

int main(int argc, char **argv)
{
   struct event_base *base;
   struct evdns_base *dns_base;

   if ((base = event_base_new()) == NULL)
   {
       return 0;
   }

   printf("Initialized libevent (method %s)\n", 
event_base_get_method(base));

   if (argc == 2 && !strcmp(argv[1], "--dns"))
   {
       if ((dns_base = evdns_base_new(base, 1)) == NULL)
       {
           return 0;
       }

       printf("Initialized evdns..\n");
   }

   printf("Starting event loop..\n");

   event_base_loop(base, 0);

   printf("Event loop ended..\n");
   return 0;
}

I've found that not loading evdns will cause the loop to exit 
immediately. Simply loading evdns is enough to keep the event loop running:

dev@blackbox:~$ ./evtest
Initialized libevent (method epoll)
Starting event loop..
Event loop ended..

dev@blackbox:~$ ./evtest --dns
Initialized libevent (method epoll)
Initialized evdns..
Starting event loop..
^C

Apparently evdns has its own event in the event loop causing libevent to 
keep the event loop alive, or something along those lines, which 
explains the issue I'm seeing?
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