def reload(self):

         old_address = self.cfg.address

         # reload conf，重新加载配置

         self.app.reload()

         self.setup(self.app)

         # reopen log files

         self.log.reopen_files()

         # do we need to change listener ?，处理监听端口变化的情况

         if old_address != self.cfg.address:

             # close all listeners

             [l.close() for l in self.LISTENERS]

             # init new listeners

             self.LISTENERS = create_sockets(self.cfg, self.log)

             listeners_str = ",".join([str(l) for l in self.LISTENERS])

             self.log.info("Listening at: %s", listeners_str)

         # spawn new workers，启动新的Worker（数量和类型来自新的配置）

         for i in range(self.cfg.workers):

             self.spawn_worker()

         # manage workers，这里会kill掉原来的Worker

         self.manage_workers()

     def manage_workers(self):

         """\

         Maintain the number of workers by spawning or killing

         as required.

         """

         if len(self.WORKERS.keys()) < self.num_workers:

             self.spawn_workers()

         workers = self.WORKERS.items()

         workers = sorted(workers, key=lambda w: w[1].age) # 按worker的age顺序排序

         while len(workers) > self.num_workers: # num_workers是配置的worker数量

             (pid, _) = workers.pop(0)

             self.kill_worker(pid, signal.SIGTERM)