Read receipts jump with lazy loading of members enabled

[bwindels]

RR positions only seem to update once the bg /members update completes, which causes a nasty pop as both the RRs suddenly click into position and the /members list loads. Instead we should surely be showing the RRs in the right place but just populating up their profiles (if needed) once /members loads?
* I just saw this again, and this time the RRs suddenly changed position quite long after the memberlist had LL'd (and updated from a handful to the full list). So i don't think it's blocked on just the bg /members completing, but something else.

[bwindels]

The RR issue really looks the same as #7261 , it's just the catchup sync taking a long time. Investigated a bit but couldn't reproduce them being blocked on /members.

I'd leave it as it is and hope for /sync to get faster?

[bwindels]

Split of from #7182

[ara4n]

yeah, i'm hoping that the spinner behaviour will make the RR jump less surprising (and/or the faster /sync will avoid the RRs going slowly). Let's close this once both have landed unless it's still a problem.

[turt2live]

I have seen this. The read receipts in general for a room appear to be blocked on the first load of the member list.

[bwindels]

@turt2live RR are indeed partially blocked on loading the members, in the sense that we only show a RR if we have the member for it. So before the members are loaded in, you only see RR for members that wrote in the timeline, as they are still part of the sync. Only once all the members have been loaded, you see all the RR.

The issue described here before was that a sync upon reconnecting (like your laptop waking up sleeping for days) could take up to some minutes, especially as a LL sync wasn't as fast as it is today, and you wouldn't see a spinner at the bottom of the timeline to indicate we were catching up. You would only receive the RR for the messages you have in your cache once the sync returns, hence them massively popping out of nowhere if you haven't synced in a long-ish time.

The latter should be solved, the former (which I suspect you are hitting) seemed acceptable to me, but if we decide it isn't we would have to do calls to /profile for every RR, just to be able to show them a few seconds earlier (/members seems to take roughly around a second to return for every 1000 members returned on matrix.org)

[bwindels]

Any thoughts?

Can't you just use a placeholder icon until the member info is in? It's already doing that while waiting for the avatar image to load anyway.

[turt2live]

On average it's taking more than a few seconds to load members for me, so I'd appreciate anything that makes the popin effect less dramatic.