streamlit does not produce WebSocket ping frames about streamlit HOT 4 OPEN

@vdonato I made the assumption that this was a regression, but it seems this problem has been present in earlier builds of streamlit as well. My bad, I've removed that tick.

I noticed the same, that the streamlit code on this area has been stable for some time. For whats it worth, it seems that tornadoweb/tornado#3376 is solving the issue of tornado closing the ws connection prematurely, but with the logic error.

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I'm wondering if this is a upstream bug in Tornado.

I did a TCP dump of the traffic locally where the websocket connection was established via curl, and indeed there is ping traffic being generated:

But the strange thing is that it terminates the connection after 30s, which seems to be a bug in tornado then.

Looking upstream, there seems to be one PR tornadoweb/tornado#3376 that attempts to solve this. I tested with the changes suggested in the PR, and this changes the traffic flow to this:

This works, but for some reason the ping comes at interval of 30s. I think this is related to the PR in question (logic error?)

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Thanks for reporting this @toredash!

Do you happen to remember the last streamlit version where you didn't observe this issue? Anecdotally, I remember inspecting network traffic and seeing websocket pings from tornado to the streamlit client at some point in the past, so there's a chance this is indeed an upstream tornado bug given that I don't think the code for this on our end has changed for quite some time (it has probably been months to years since the code related to this has been changed significantly).

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