ioloop.py 文件源码

def _setup_logging(self):
        """The IOLoop catches and logs exceptions, so it's
        important that log output be visible.  However, python's
        default behavior for non-root loggers (prior to python
        3.2) is to print an unhelpful "no handlers could be
        found" message rather than the actual log entry, so we
        must explicitly configure logging if we've made it this
        far without anything.

        This method should be called from start() in subclasses.
        """
        if not any([logging.getLogger().handlers,
                    logging.getLogger('tornado').handlers,
                    logging.getLogger('tornado.application').handlers]):
            logging.basicConfig()