启动
        :param host: 监听IP
        :param port: 监听端口
        :param debug: 是否debug
        :param workers: workers数量
        :return:

def run(self, host=None, port=None, debug=None, workers=None):
        """
        启动
        :param host: 监听IP
        :param port: 监听端口
        :param debug: 是否debug
        :param workers: workers数量
        :return:
        """
        self._validate_cmds()

        if host is None:
            host = constants.SERVER_HOST
        if port is None:
            port = constants.SERVER_PORT
        if debug is not None:
            self.debug = debug

        workers = workers if workers is not None else 1

        logger.info('Running server on %s, debug: %s, workers: %s',
                    (host, port), self.debug, workers)

        self._prepare_server((host, port))
        setproctitle.setproctitle(self._make_proc_name('master'))
        # 只能在主线程里面设置signals
        self._handle_parent_proc_signals()
        self._spawn_workers(workers, self._worker_run)