Flood of duplicate GetBreakoutJoinURL requests when breakouts are started

[capilkey]

We've seen a few times now that a server can be put under very heavy load when breakouts are started with 30+ users in a meeting. Going through the akka-apps logs shows multiple (12+) requests to get a breakout join URL for the same user and same breakout room. One meeting can generate thousands of requests and flood the server with messages to process. At the moment it's unclear if it's the server or the client causing the flood.

Two of the cases we've seen have been when the breakout rooms are configured to be "free join" and that might be a trigger to the problem, but at the moment it's unconfirmed.

We need to ensure that there is only one request made to get the join URL.

[capilkey]

The culprit is this code

bigbluebutton/bigbluebutton-html5/imports/ui/components/breakout-join-confirmation/container.jsx

Lines 30 to 36 in 9dcbd51

	export default withTracker(({ breakout, mountModal, breakoutName }) => {
	const isFreeJoin = breakout.freeJoin;
	const { breakoutId } = breakout;
	const url = getURL(breakoutId);
	if (isFreeJoin && !url) {
	requestJoinURL(breakoutId);
	}

Because the request to get the join URL is in the Tracker it is going to run whenever and if the server is behind in messages the client will request over and over again for the same thing.

There's also a secondary issue in the component where it will request a join URL whenever the select box changes, no matter if the request was previously just made or not.

I think what we need is to only request the join URL once the user has actually selected to join the room. There's no point in requesting it early this.