Consistent lag spike when entering Song Select on 2024.718.0

[jvyden]

Type

Performance

Bug description

Definitely seems to be a regression since last release. It's possible this scales with the number of songs you have because in the Discord links I post below, there's a user with 86k maps that has a spike that lasts several seconds as opposed to the smaller stutters I show in my video, with only 12k maps.

Screenshots or videos

2024-07-18.17-18-21.mp4

I also see this being reported in Discord:

• https://discord.com/channels/188630481301012481/1097318920991559880/1263445746900799490
• https://discord.com/channels/188630481301012481/1097318920991559880/1263453062182211664

Version

2024.718.0

Logs

compressed-logs.zip

[Ladwick]

I'm having the same issue.

[bdach]

@jvyden since you are a person that should not be scared of an IDE, could you do me a solid and see if reverting #28890 fixes it? I have a suspicion what the cause is but it'd be probably easier for you to confirm.

[jvyden]

Sure, I'll take a look right now.

[jvyden]

Sorry for the delay. I have discovered that, if anything, the IDE is scared of me.

Anyways, the stutter still appears to be there after reverting the commits in those PRs.

I would do some profiling/debugging myself but my computer has decided that now is the time to fight back.

[jvyden]

Ended up reformatting my entire OS just to get to the bottom of this issue... 😅

If I'm understanding correctly, it looks like the stutter is caused by a big Realm query happening on the update thread:

https://github.com/ppy/osu/blob/master/osu.Game/Screens/Select/BeatmapCarousel.cs#L132
this is called by a line added as part of #28769:
https://github.com/peppy/osu/blob/8f271170e94fa7fdf547b70b5f107a7679194d0c/osu.Game/Screens/Select/BeatmapCarousel.cs#L284

(Lazily) reverting the changes of #28769 fixes the stutter.

[frenzibyte]

cc @peppy