gunicorn 信号处理（SIGHUP，SIGUSR2）

 1     def reload(self):
 2         old_address = self.cfg.address
 3  
 4         # reload conf，重新加载配置
 5         self.app.reload()
 6         self.setup(self.app)
 7  
 8         # reopen log files
 9         self.log.reopen_files()
10  
11         # do we need to change listener ?，处理监听端口变化的情况
12         if old_address != self.cfg.address:
13             # close all listeners
14             [l.close() for l in self.LISTENERS]
15             # init new listeners
16             self.LISTENERS = create_sockets(self.cfg, self.log)
17             listeners_str = ",".join([str(l) for l in self.LISTENERS])
18             self.log.info("Listening at: %s", listeners_str)
19  
20         # spawn new workers，启动新的Worker（数量和类型来自新的配置）
21         for i in range(self.cfg.workers):
22             self.spawn_worker()
23  
24         # manage workers，这里会kill掉原来的Worker
25         self.manage_workers()

 1     def manage_workers(self):
 2         """ 3         Maintain the number of workers by spawning or killing
 4         as required.
 5         """
 6         if len(self.WORKERS.keys()) < self.num_workers:
 7             self.spawn_workers()
 8  
 9         workers = self.WORKERS.items()
10         workers = sorted(workers, key=lambda w: w[1].age) # 按worker的age顺序排序
11         while len(workers) > self.num_workers: # num_workers是配置的worker数量
12             (pid, _) = workers.pop(0)
13             self.kill_worker(pid, signal.SIGTERM)