Race condition for local track subscribed

[tobowers]

Select which package(s) are affected

@livekit/rtc-node

Describe the bug

race condition in track subscription.

We have some code that that kept crashing our server yesterday. There's a problem with this line:

node-sdks/packages/livekit-rtc/src/room.ts

Line 262 in f198246

publication!.resolveFirstSubscription();

Where sometimes (it's really unclear when) the publication can be undefined:

TypeError#1: undefined is not an object (evaluating 'publication.resolveFirstSubscription')

You can see on that line that there's a ! in the typescript, so lint must have seen it.

This happened when we were reconnecting to a room with same participant name, same room name. So maybe the track was still published from the previous connection?

Reproduction

unfortunately not sure

Logs

System Info

Bun 1.2.8 
"@livekit/rtc-node": "^0.13.10",
"livekit-server-sdk": "^2.11.0",

LiveKit server version

LiveKit cloud

Severity

annoyance

Additional Information

No response

[lukasIO]

thanks for the report! do you happen to have the complete logs of this instance?

you put Bun in system info, so you're not running this in node, right?

[tobowers]

thanks for the report! do you happen to have the complete logs of this instance?

you put Bun in system info, so you're not running this in node, right?

Correct we are running in Bun. Mostly things work fine. Early in the connection process we sometimes get errors like these. Maybe 1 in 20-30 times. They are un caught errors though which bubble up.

[lukasIO]

got it, I was hoping you'd have surrounding logs to know what order of events might be causing this to happen in the first place

[pzerelles]

I tracked down a similar problem, or maybe it is the same, where the response for a publishTrack event is awaited as a promise and the event loop processes other events first, e.g. the localTrackPublished event, that requires a track to be in the local participants trackPublications map, but because of different handling of the event loop in Bun, this leads to an error.

I will create a PR with a patch that will force the event loop to finish outstanding promises first before the localTrackPublished event is processed.