Python-SocketIO client frequent websocket disconnect from the server

[prawebdesign]

Hi,

I'm experiencing persistent WebSocket disconnections (every 30 second to few minutes) in production on Azure App Service during long-running operations (60-120 seconds), despite extensive timeout configurations. (Switching to HTTP long-polling seems to have fixed disconnection issues) I need community validation: Is WebSocket fundamentally unsuitable for my architecture, or am I missing something?

Architecture Overview

Client (Browser/Python Script)
    ↓
Azure Application Gateway (~230s timeout limit)
    ↓
Nginx Reverse Proxy (Docker container)
    ↓
Gunicorn with UvicornWorker
    ↓
Django + Socket.IO AsyncServer
    ↓
Redis (AsyncRedisManager for multi-worker coordination)

Technology Versions

• Backend: Django + python-socketio==5.15.1 + python-engineio==4.12.3
• Server: Gunicorn 23.0.0 with uvicorn.workers.UvicornWorker
• Proxy: Nginx 1.25 in Docker container
• Clients:
  • Python: python-socketio client with Azure AD authentication
  • Angular: socket.io-client browser library
• Infrastructure: Azure App Service (Linux container) + Application Gateway
• Message Queue: Redis with AsyncRedisManager

Use Case

Test automation system where:

1. Client sends test execution commands via Socket.IO
2. Server processes tests 3. Server sends real-time progress updates back to client
3. Client must maintain connection throughout entire test execution

Symptoms

• Frequency: Disconnections every every 30 second to few minutes during active test execution
• Impact: server disconnects client mid execution frequently and client tries to reconnect - Environment: Only production (Azure App Service); local Docker works fine

Server-Side Logs (WebSocket Mode)

[DISCONNECT] ===== CLIENT DISCONNECT DETECTED =====

2025-12-17T15:02:31.5448739Z [DISCONNECT] SID: KVyrE-tKDZ5D0y5gAAAD

2025-12-17T15:02:31.5449026Z [DISCONNECT] Time: 1765983751.5358

2025-12-17T15:02:31.5449058Z [DISCONNECT] Worker PID: 44

2025-12-17T15:02:31.5449077Z [DISCONNECT] Call stack:

2025-12-17T15:02:31.54491Z [DISCONNECT] File "/usr/local/bin/gunicorn", line 7, in <module>

2025-12-17T15:02:31.5449157Z     sys.exit(run())

2025-12-17T15:02:31.544918Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/gunicorn/app/wsgiapp.py", line 66, in run

2025-12-17T15:02:31.5449202Z     WSGIApplication("%(prog)s [OPTIONS] [APP_MODULE]", prog=prog).run()

2025-12-17T15:02:31.544923Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/gunicorn/app/base.py", line 235, in run

2025-12-17T15:02:31.5449249Z     super().run()

2025-12-17T15:02:31.5449272Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/gunicorn/app/base.py", line 71, in run

2025-12-17T15:02:31.544929Z     Arbiter(self).run()

2025-12-17T15:02:31.5449312Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/gunicorn/arbiter.py", line 201, in run

2025-12-17T15:02:31.5449331Z     self.manage_workers()

2025-12-17T15:02:31.5449354Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/gunicorn/arbiter.py", line 570, in manage_workers

2025-12-17T15:02:31.5449393Z     self.spawn_workers()

2025-12-17T15:02:31.5449418Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/gunicorn/arbiter.py", line 641, in spawn_workers

2025-12-17T15:02:31.5449437Z     self.spawn_worker()

2025-12-17T15:02:31.5449465Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/gunicorn/arbiter.py", line 608, in spawn_worker

2025-12-17T15:02:31.5449482Z     worker.init_process()

2025-12-17T15:02:31.5449505Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/uvicorn/workers.py", line 66, in init_process

2025-12-17T15:02:31.5449525Z     super(UvicornWorker, self).init_process()

2025-12-17T15:02:31.5449548Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/gunicorn/workers/base.py", line 143, in init_process

2025-12-17T15:02:31.5449568Z     self.run()

2025-12-17T15:02:31.544959Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/uvicorn/workers.py", line 98, in run

2025-12-17T15:02:31.544961Z     return asyncio.run(self._serve())

2025-12-17T15:02:31.5449652Z [DISCONNECT] File "/usr/local/lib/python3.13/asyncio/runners.py", line 195, in run

2025-12-17T15:02:31.5449672Z     return runner.run(main)

2025-12-17T15:02:31.5449695Z [DISCONNECT] File "/usr/local/lib/python3.13/asyncio/runners.py", line 118, in run

2025-12-17T15:02:31.5449716Z     return self._loop.run_until_complete(task)

2025-12-17T15:02:31.5449742Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/uvicorn/protocols/websockets/websockets_impl.py", line 238, in run_asgi

2025-12-17T15:02:31.5449772Z     result = await self.app(self.scope, self.asgi_receive, self.asgi_send)

2025-12-17T15:02:31.5449799Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/uvicorn/middleware/proxy_headers.py", line 78, in __call__

2025-12-17T15:02:31.544982Z     return await self.app(scope, receive, send)

2025-12-17T15:02:31.5449841Z [DISCONNECT] File "/usr/src/app/gemini/socketio_asgi.py", line 35, in application

2025-12-17T15:02:31.5449861Z     await sio.handle_request(scope, receive, send)

2025-12-17T15:02:31.5449905Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/socketio/async_server.py", line 452, in handle_request

2025-12-17T15:02:31.5449928Z     return await self.eio.handle_request(*args, **kwargs)

2025-12-17T15:02:31.5449952Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/engineio/async_server.py", line 282, in handle_request

2025-12-17T15:02:31.5449974Z     r = await self._handle_connect(environ, transport,

2025-12-17T15:02:31.5449998Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/engineio/async_server.py", line 473, in _handle_connect

2025-12-17T15:02:31.5450018Z     ret = await s.handle_get_request(environ)

2025-12-17T15:02:31.5450042Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/engineio/async_socket.py", line 91, in handle_get_request

2025-12-17T15:02:31.5450065Z     return await getattr(self, '_upgrade_' + transport)(environ)

2025-12-17T15:02:31.5450093Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/engineio/async_socket.py", line 149, in _upgrade_websocket

2025-12-17T15:02:31.5450113Z     return await ws(environ)

2025-12-17T15:02:31.5450154Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/engineio/async_drivers/asgi.py", line 258, in __call__

2025-12-17T15:02:31.5450176Z     await self.handler(self)

2025-12-17T15:02:31.5450199Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/engineio/async_socket.py", line 260, in _websocket_handler

2025-12-17T15:02:31.545022Z     await self.close(wait=False, abort=True,

2025-12-17T15:02:31.5450242Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/engineio/async_socket.py", line 120, in close

2025-12-17T15:02:31.545026Z     await self.server._trigger_event(

2025-12-17T15:02:31.5450286Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/engineio/async_server.py", line 532, in _trigger_event

2025-12-17T15:02:31.5450309Z     ret = await run_async_handler()

2025-12-17T15:02:31.5450331Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/engineio/async_server.py", line 509, in run_async_handler

2025-12-17T15:02:31.5450353Z     return await self.handlers[event](*args)

2025-12-17T15:02:31.5450401Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/socketio/async_server.py", line 712, in _handle_eio_disconnect

2025-12-17T15:02:31.5450424Z     await self._handle_disconnect(eio_sid, n, reason)

2025-12-17T15:02:31.5450536Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/socketio/async_server.py", line 589, in _handle_disconnect

2025-12-17T15:02:31.594656Z KVyrE-tKDZ5D0y5gAAAD is leaving room copied_scriptc315050f-5e8a-428e-bf7e-825798c40a7f6967-725261 [/]

2025-12-17T15:02:31.5947116Z INFO 2025-12-17 07:02:31,594 socketio.server leave_room:319 KVyrE-tKDZ5D0y5gAAAD is leaving room copied_scriptc315050f-5e8a-428e-bf7e-825798c40a7f6967-725261 [/]await self._trigger_event('disconnect', namespace, sid,

2025-12-17T15:02:34.829484Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/socketio/async_server.py", line 665, in _trigger_event

2025-12-17T15:02:34.8294845Z INFO 2025-12-17 07:02:34,828 engineio.server send:77 4EqAhHNsrCeW2YuOAAAA: Sending packet MESSAGE data 320[{"status":"received","message_id":"e4e9d4e7-51ba-445f-8efd-c904e558d2b2"}]

2025-12-17T15:02:34.8294876Z     return await handler.trigger_event(event, *args)

2025-12-17T15:02:34.8294915Z [DISCONNECT] File "/usr/local/lib/python3.13/site-packages/socketio/async_namespace.py", line 43, in trigger_event

2025-12-17T15:02:34.829494Z     ret = await handler(*args[:-1])

2025-12-17T15:02:34.829497Z [DISCONNECT] File "/usr/src/app/tp/socketio_consumers.py", line 107, in on_disconnect

2025-12-17T15:02:34.8294996Z     for line in traceback.format_stack():

2025-12-17T15:02:34.8295022Z

2025-12-17T15:02:34.829505Z === CLIENT DISCONNECT ====```



### Client-Side Observations

[PYTHON CLIENT] ===== DISCONNECT EVENT =====

[PYTHON CLIENT] Disconnected from server at 1765991928.5393806

[PYTHON CLIENT] Was in room: copied_scriptc315050f-5e8a-428e-bf7e-825798c40a7f6967-725264

[PYTHON CLIENT] Connected status: True

[PYTHON CLIENT] SIO object exists: True

[PYTHON CLIENT] SIO connected: True

[PYTHON CLIENT] Call stack at disconnect:

[PYTHON CLIENT] File "\\python_environments\py312\python-3.12.2.amd64\Lib\threading.py", line 1030, in _bootstrap

self._bootstrap_inner()

[PYTHON CLIENT] File "\\python_environments\py312\python-3.12.2.amd64\Lib\threading.py", line 1073, in _bootstrap_inner

self.run()

[PYTHON CLIENT] File "\\python_environments\py312\python-3.12.2.amd64\Lib\threading.py", line 1010, in run

self._target(*self._args, **self._kwargs)

[PYTHON CLIENT] File "\\python_environments\py312\python-3.12.2.amd64\Lib\site-packages\engineio\client.py", line 560, in _read_loop_websocket

self._trigger_event('disconnect', self.reason.TRANSPORT_ERROR,

[PYTHON CLIENT] File "\\python_environments\py312\python-3.12.2.amd64\Lib\site-packages\engineio\client.py", line 465, in _trigger_event

return self.handlersevent

[PYTHON CLIENT] File "\\python_environments\py312\python-3.12.2.amd64\Lib\site-packages\socketio\client.py", line 546, in _handle_eio_disconnect

self._trigger_event('disconnect', n, reason)

[PYTHON CLIENT] File "\\python_environments\py312\python-3.12.2.amd64\Lib\site-packages\socketio\client.py", line 449, in _trigger_event

return handler(*args[:-1])

[PYTHON CLIENT] Will attempt reconnection...

[PYTHON CLIENT] ================================```

What Works vs. What Doesn't

Configuration	Local Docker	Azure Production
transports=['websocket']	✅ Works	❌ Disconnects every 30 second to few minutes
transports=['websocket', 'polling']	✅ Works	❌ Disconnects every 30 second to few minutes
transports=['polling']	✅ Works	✅ WORKS

Community Input Needed

1. Is this a known limitation? Are there documented issues with WebSocket through Azure Application Gateway + Nginx + Gunicorn stack?

2. Am I missing a configuration? Is there an Azure-specific setting or Nginx directive that makes WebSocket stable in this environment?

3. Is polling acceptable for production? Given 60-120 second operations with real-time progress updates, is HTTP long-polling a viable long-term solution?

4. Has anyone solved this differently? Alternative approaches that maintain WebSocket in similar architectures?

5. What's the root cause? If all timeouts are fixed, what mechanism is still causing the Engine.IO abort=True disconnections?

Any insights from the community would be greatly appreciated!