To keep ipc channel being read from worker process, default loop
should not be stopped. To join all worker threads, now we use
dedicated thread to do this. When all worker threads are joined,
ev_async_send sends message to default loop, and it is finally
stopped.
The control process handles signals, reads configuration, reads
private keys, and bind port (which may be privileged one). It never
drop privileges, so that it can execute new binary with the same
privilege. It forks worker process. The worker process handles all
incoming connections. It drops privilege.
Tatsuhiro Tsujikawa
Vernon Tang