turnado websocket occur close event with code:1006 - websocket

Question

I'm a beginner using tornado and WebSocket. I'm trying to write a websocket demo with tornado to send and receive messages. However, when the client was connected to the server and was waiting to receiving messages from the server, a close event occurred with 1006 code which isbelow.
CloseEvent {isTrusted: true, wasClean: false, code: 1006, reason: '',
type: 'close', …} bubbles: false cancelBubble: false cancelable: false
code: 1006 composed: false currentTarget: WebSocket {url:
'ws://localhost:9998/ws', readyState: 3, bufferedAmount: 0, onopen:
null, onerror: null, …} defaultPrevented: false eventPhase: 0
isTrusted: true path: [] reason: "" returnValue: true srcElement:
WebSocket {url: 'ws://localhost:9998/ws', readyState: 3,
bufferedAmount: 0, onopen: null, onerror: null, …} target: WebSocket
{url: 'ws://localhost:9998/ws', readyState: 3, bufferedAmount: 0,
onopen: null, onerror: null, …} timeStamp: 75840 type: "close"
wasClean: false [[Prototype]]: CloseEvent
When I'm trying to debug where caused the close event, I found that the code in the
tornado/web.py
caused the close event.
When this code self.request.connection.finish() was executed ,the close event occurred. I don't know why this code can cause close event.
future = self.flush(include_footers=True)
self.request.connection.finish()
self._log()
self._finished = True
self.on_finish()
self._break_cycles()
return future
Here is my demo code, is there anything wrong with my code that cause the close event?
The sever code:
import tornado.ioloop
import tornado.web
import tornado.websocket
import time
class ConnectHandler(tornado.websocket.WebSocketHandler) :
def simple_init(self):
self.last = time.time();
self.stop = False;
def check_origin(self, origin) :
return True
def open(self) :
self.simple_init();
print("New client connecting")
self.write_message('Welcome')
print("New client connected")
def on_close(self) :
print("connection is closed")
self.loop.stop();
def on_message(self, message) :
self.write_message('new message :' + message)
class Application(tornado.web.Application) :
def __init__(self) :
handlers = [
(r'/ws', ConnectHandler)
]
tornado.web.Application.__init__(self, handlers)
if __name__ == "__main__" :
app = Application()
app.listen(8889)
tornado.ioloop.IOLoop.current().start()
The client code:
from websocket import create_connection
def short_lived_connection():
ws = create_connection("ws://localhost:9998/ws");
print("send hello server");
ws.send("hello, server");
print("sent");
print("receiving...");
result = ws.recv();
print("Received '%s'" % result);
ws.close();
# Press the green button in the gutter to run the script.
if __name__ == '__main__':
short_lived_connection()