runserver.py 文件源码

def stop_child(http_server, parent_pid):
    """
    Tornado's callback function which checks PID of the parent process.
    If PID of the parent process is changed (parent has stopped), will
    stop **IOLoop**.
    """
    if os.getppid() != parent_pid:
        # Stop HTTP server (stop accept new requests)
        http_server.stop()
        # Stop IOLoop
        tornado.ioloop.IOLoop.instance().add_callback(
            tornado.ioloop.IOLoop.instance().stop)