Warning from engineio: Cannot send to sid <sid>

[billysan]

This seems to happen only with a message_queue (tried both redis and rabbitmq)

2022-08-09 21:10:26,766 - INFO - 14 - 140315009483632 - socketio.server      - server.py                 - 317  - emitting event "user_logged_in" to all [/]
emitting event "user_logged_in2" to all [/]
2022-08-09 21:10:26,774 - INFO - 14 - 140315009483632 - socketio.server      - server.py                 - 317  - emitting event "user_logged_in2" to all [/]
pubsub message: emit
2022-08-09 21:10:26,776 - INFO - 14 - 140315008430960 - socketio.server      - pubsub_manager.py         - 165  - pubsub message: emit
pwBZnn83CV-eNkioAAAA: Sending packet MESSAGE data 2["user_logged_in",{"ye":45}]
2022-08-09 21:10:26,777 - INFO - 14 - 140315008430960 - engineio.server      - socket.py                 - 89   - pwBZnn83CV-eNkioAAAA: Sending packet MESSAGE data 2["user_logged_in",{"ye":45}]
pubsub message: emit
2022-08-09 21:10:26,778 - INFO - 14 - 140315008430960 - socketio.server      - pubsub_manager.py         - 165  - pubsub message: emit
pwBZnn83CV-eNkioAAAA: Sending packet MESSAGE data 2["user_logged_in2",{"ye":45}]
2022-08-09 21:10:26,779 - INFO - 14 - 140315008430960 - engineio.server      - socket.py                 - 89   - pwBZnn83CV-eNkioAAAA: Sending packet MESSAGE data 2["user_logged_in2",{"ye":45}]
pwBZnn83CV-eNkioAAAA: Received packet CLOSE data
2022-08-09 21:10:26,880 - INFO - 14 - 140315009486352 - engineio.server      - socket.py                 - 52   - pwBZnn83CV-eNkioAAAA: Received packet CLOSE data
pubsub message: disconnect
2022-08-09 21:10:26,886 - INFO - 14 - 140315008430960 - socketio.server      - pubsub_manager.py         - 165  - pubsub message: disconnect
emitting event "user_logged_in" to all [/]
2022-08-09 21:10:29,777 - INFO - 14 - 140315009483632 - socketio.server      - server.py                 - 317  - emitting event "user_logged_in" to all [/]
emitting event "user_logged_in2" to all [/]
2022-08-09 21:10:29,778 - INFO - 14 - 140315009483632 - socketio.server      - server.py                 - 317  - emitting event "user_logged_in2" to all [/]
pubsub message: emit
2022-08-09 21:10:29,780 - INFO - 14 - 140315008430960 - socketio.server      - pubsub_manager.py         - 165  - pubsub message: emit
Cannot send to sid pwBZnn83CV-eNkioAAAA
2022-08-09 21:10:29,780 - WARNING - 14 - 140315008430960 - engineio.server      - server.py                 - 230  - Cannot send to sid pwBZnn83CV-eNkioAAAA
pubsub message: emit
2022-08-09 21:10:29,782 - INFO - 14 - 140315008430960 - socketio.server      - pubsub_manager.py         - 165  - pubsub message: emit
Cannot send to sid pwBZnn83CV-eNkioAAAA
2022-08-09 21:10:29,782 - WARNING - 14 - 140315008430960 - engineio.server      - server.py                 - 230  - Cannot send to sid pwBZnn83CV-eNkioAAAA

Packages:

redis==3.3.8
python-socketio==5.7.1
kombu==5.2.4
gevent==1.4.0
gevent-websocket==0.10.1
gunicorn==20.1.0

Running flask with "-k geventwebsocket.gunicorn.workers.GeventWebSocketWorker"

Using a test client with python-socketio:

import socketio

sio = socketio.Client(ssl_verify=False, handle_sigint=True, logger=True, engineio_logger=True)

@sio.event
def connect():
    print('********************************\nconnection established\n********************************\n' * 10)

@sio.on("user_logged_in")
def my_message(data):
    print('message received with ', data)

@sio.on("user_logged_in2")
def my_message(data):
    print('message received with', data)

@sio.event
def disconnect():
    print('********************************\nDISCONNECT\n********************************\n' * 10)

sio.connect('http://server/', transports=['websocket'])
sio.wait()

Anything I might be missing?

[miguelgrinberg]

At 21:10:26,880 your user pwBZnn83CV-eNkioAAAA disconnected. Then at 21:10:29,780 you are emitting to this user. The error occurs because you are emitting to a user that is unknown. Can you explain why does this happen?

[billysan]

Thanks for the quick reply!

I'm emitting on a thread in a loop but I am not addressing any client in particular, just:

            self.socketio.emit("user_logged_in", {'ye': 45})
            self.socketio.emit("user_logged_in2", {'ye': 45})

Where self is the Flask server:

socketio = SocketIO(
            self,
            message_queue='redis://redis:6379',
            cors_allowed_origins=[],
            ping_timeout=5,
            ping_interval=5,
            logger=True,
            engineio_logger=True,
            monitor_clients=True
        )

[billysan]

I thought that monitor_clients will remove the user from the queue and avoid emitting to them again?

[miguelgrinberg]

The monitor_clients option is for clients that suddenly stop communicating with the server, it is not for clients that disconnect gracefully as in this case.

I think what's happening here is a race condition between the two emits and the disconnect, which happen at about the same time. How often does this happen for you? To be able to debug this I need a reliable way to reproduce the problem, so I need any suggestions you may have, or if you can create a small example that does it even better.

[billysan]

on my Flask server:

        socketio = SocketIO(
            self,
            message_queue='redis://redis:6379',
            cors_allowed_origins=[],
            logger=True,
            engineio_logger=True
        )
        self.socketio = socketio

        from threading import Thread
        new_thread = Thread(target=self.test_socketio)
        new_thread.start()

    def test_socketio(self):
        while True:
            import time
            import random
            self.socketio.emit("user_logged_in", {'ye': 45})
            self.socketio.emit("user_logged_in2", {'ye': 45})
            time.sleep(3)

The client is the same client as previously pasted.

I also tried with a longer interval (30 seconds) and still got the warnings.

Anyting else? do you need the gunicorn / WSGI stuff as well?

[miguelgrinberg]

I have been unable to reproduce your error with your instructions, sadly.

Regardless, I did fix the issue I indicated above in which disconnects were being put in the message queue, something that is unnecessary in most situations. Do you want to give the main branch of python-socketio a try? Let me know if the problem still occurs. In that case I think it would be best if you create a complete server that I can use along your client to reproduce the issue.

[billysan]

Thanks Miguel! I will give it a try in the next few days. Thank you for being attentive and helping out with the fix 🙏🏾

…

On Mon, Aug 15, 2022, 18:14 Miguel Grinberg ***@***.***> wrote: I have been unable to reproduce your error with your instructions, sadly. Regardless, I did fix the issue I indicated above in which disconnects where being put in the message queue, something that is unnecessary in most situations. Do you want to give the main branch of python-socketio a try? Let me know if the problem still occurs. In that case I think it would be best if you create a complete server that I can use along your client to reproduce the issue. — Reply to this email directly, view it on GitHub <#1866 (reply in thread)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AE4Q56HFOPILHCSK7KTJAB3VZJNGJANCNFSM56BYNRYQ> . You are receiving this because you authored the thread.Message ID: <miguelgrinberg/Flask-SocketIO/repo-discussions/1866/comments/3399168@ github.com>