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Description
Describe your environment
OS: Ubuntu 22.04
Python version: 3.10.12
Package version: 0.47b0
What happened?
The WebSocketHandler.finish method, called after the WebSocket upgrade, results in lost context at https://github.com/tornadoweb/tornado/blob/1f8b2d78fee5e5a15e686815e0285d4a3c831a2c/tornado/websocket.py#L929
Steps to Reproduce
from tornado import websocket, web, ioloop
class WebsocketHandler(websocket.WebSocketHandler):
def open(self):
print("WebSocket opened")
def on_message(self, message):
self.write_message(u"You said: " + message)
def on_close(self):
print("WebSocket closed")
app = web.Application([
(r'/ws', WebsocketHandler),
])
if __name__ == '__main__':
app.listen(8888)
ioloop.IOLoop.instance().start()opentelemetry-instrument \
--traces_exporter console \
--metrics_exporter console \
--logs_exporter console \
--service_name cmc-front-end \
python \
main.pyconst ws = new WebSocket("ws://localhost:8888/ws");
ws.onopen = function() {
ws.send("Hello, world");
};
ws.onmessage = function (evt) {
console.log(evt)
};deno run main.jsExpected Result
Context to flow from the protocol upgrade to the message handling.
Actual Result
Context is lost after the initial phase is finished.
Additional context
No response
Would you like to implement a fix?
Yes
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devmonkey22 commentedon May 9, 2025
I found the same issue. Even though
WebSocketHandleris a subclass of tornado'sRequestHandler, its flow for the WebSocket upgrade, etc causes the normal instrumentation to not be correct. The currentRequestHandlerhooks areprepare,on_finish, andlog_exception. However, for aWebSocketHandler, it needs to patchWebSocketHandler.on_close(or similar) instead ofon_finishin order to start/record the metrics and traces properly for the websocket lifetime.I'm not sure how people want the request/response sizes reported. I saw some similar tickets for real-time connections and how OTel should report these, but not sure if it should collect
on_messagedata sizes or other metrics to collect data received/sent or not.Add tornado WebSocketHandler instrumentation support. (open-telemetry…