Websocket heartbeat

[djwessel]

Why does setting heartbeat in ws_connect default to _pong_heartbeat being set to heartbeat / 2 with no option to override this value?

In websockets.WebSocketApp, you have the option to set the ping_timeout separate from the ping_interval: https://websocket-client.readthedocs.io/en/latest/examples.html#ping-pong-usage

I want an option to just send ping heartbeats and not bother if the pong is not responded to

[Dreamsorcerer]

I want an option to just send ping heartbeats and not bother if the pong is not responded to

What purpose does that serve?

[djwessel]

At the bare minimum, I would want to be able to change the _pong_heartbeat time to change it to a value other than heartbeat / 2.

But my real motivation is to handle an issue I am experiencing with the Azure WebPubsub service. I am experiencing that the server is closing my connection after ~20 seconds of no activity going over the channel. However, if I send a ping every 5-10 seconds, the server keeps the connection alive. When I was using a websockets.WebSocketApp-based implementation, the solution was to just set the ping_interval (notice I wasn't setting the ping_timeout, so I was not expecting a response from the server). This kept the connection alive without issue.

Now, I want to switch over to an aiohttp-based solution. To keep the connection alive, I use the heartbeat arg on ws_connect. Unfortunately, it seems that sometimes the server fails to respond with a pong message in time for the heartbeat / 2 timeout (not sure if this is due to network instability, or just poor implementation on the Azure side, or if it is an issue on the aiohttp side). As such, aiohttp then closes the connection automatically, thinking the connection is no longer alive.

I've opened an issue on the azure client SDK Azure/azure-sdk-for-python#42162 to start using the appropriate heartbeat arguments of websockets.WebSocketApp.run_forever and session.ws_connect for their sync and async implementations, however, if there is no way to adapt the _pong_heartbeat timeout, the change will still result in the connection getting closed whenever the pong message timeout is hit.

[Dreamsorcerer]

It sounds like the service should be getting a fix. I think currently atleast, you'd only be able to do this by sending pings manually, rather than using the heartbeat feature.

[djwessel]

So there will be no option to manually set the _pong_heartbeat timeout in the future?

[Dreamsorcerer]

To me, it feels like a hack to workaround another system that is broken. The heartbeat feature is meant to automatically check if the other end is still alive, but this is not what you want it to do. I believe you're the first to ask for such a feature, so currently I wouldn't expect this to be added.