ioloop.py 文件源码

def __init__(self, callback, callback_time, io_loop=None):
        # PeriodicCallback require callback_time to be positive
        warnings.warn("""DelayedCallback is deprecated.
        Use loop.add_timeout instead.""", DeprecationWarning)
        callback_time = max(callback_time, 1e-3)
        super(DelayedCallback, self).__init__(callback, callback_time, io_loop)