autoreload.py 文件源码

def start(io_loop=None, check_time=500):
    """Begins watching source files for changes.

    .. versionchanged:: 4.1
       The ``io_loop`` argument is deprecated.
    """
    io_loop = io_loop or ioloop.IOLoop.current()
    if io_loop in _io_loops:
        return
    _io_loops[io_loop] = True
    if len(_io_loops) > 1:
        gen_log.warning("tornado.autoreload started more than once in the same process")
    if _has_execv:
        add_reload_hook(functools.partial(io_loop.close, all_fds=True))
    modify_times = {}
    callback = functools.partial(_reload_on_update, modify_times)
    scheduler = ioloop.PeriodicCallback(callback, check_time, io_loop=io_loop)
    scheduler.start()