[HOLD] Chat disappears in High Traffic account

[kavimuru]

HOLD on #23223

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Action Performed:

1. Go to some HT channel (https://new.expensify.com/r/8292963527436014).Please do not post testing messages as this is a real channel with real customers.
2. Scroll upwards.
3. After a while the chat breaks and just a blank area appears.
4. Try scroll up and down and notice a hug gap appears between the chat messages

Expected Result:

While scrolling upwards the messages should load in order from and there should be no gap and chat should not break

Actual Result:

Chat breaks and a huge gap is introduced between messages

Workaround:

Can the user still use Expensify without this being fixed? Have you informed them of the workaround?

Platforms:

Which of our officially supported platforms is this issue occurring on?

• Android / native
• Android / Chrome
• iOS / native
• iOS / Safari
• MacOS / Chrome / Safari
• MacOS / Desktop

Version Number:
Reproducible in staging?: needs reproduction
Reproducible in production?: needs reproduction
If this was caught during regression testing, add the test name, ID and link from TestRail:
Email or phone of affected tester (no customers):
Logs: https://stackoverflow.com/c/expensify/questions/4856
Notes/Photos/Videos: Any additional supporting documentation

ht-scroll-2.mov

ht-scroll.mov

Expensify/Expensify Issue URL:
Issue reported by: @Talha345
Slack conversation: https://expensify.slack.com/archives/C049HHMV9SM/p1689786243613119

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[melvin-bot]

Triggered auto assignment to @mateocole (Bug), see https://stackoverflow.com/c/expensify/questions/14418 for more details.

[melvin-bot]

Bug0 Triage Checklist (Main S/O)

• This "bug" occurs on a supported platform (ensure Platforms in OP are ✅)
• This bug is not a duplicate report (check E/App issues and #expensify-bugs)
  • If it is, comment with a link to the original report, close the issue and add any novel details to the original issue instead
• This bug is reproducible using the reproduction steps in the OP. S/O
  • If the reproduction steps are clear and you're unable to reproduce the bug, check with the reporter and QA first, then close the issue.
  • If the reproduction steps aren't clear and you determine the correct steps, please update the OP.
• This issue is filled out as thoroughly and clearly as possible
  • Pay special attention to the title, results, platforms where the bug occurs, and if the bug happens on staging/production.
• I have reviewed and subscribed to the linked Slack conversation to ensure Slack/Github stay in sync

[mateocole]

@kavimuru when I am reproducing, this happens to a certain extent on my end also. But, the chats load much faster. Is the pagination more of a internet speed issue here, or a fundamental engineering issue? Curious if when you reproduce this if the pagination matches the videos, or is different?

[melvin-bot]

Triggered auto assignment to @flaviadefaria (Bug), see https://stackoverflow.com/c/expensify/questions/14418 for more details.

[flaviadefaria]

I experience this issue all the time with my DMs. @marcaaron is this going to be handled by the pagination project? Should I close this?

[kavimuru]

@mateocole I was not able to reproduce. It was reproduced only by the contributor @Talha345. So I created a GH ticket with needs reproduction label.

[marcaaron]

This will likely be resolved by the Comment Linking project.

cc @roryabraham and @perunt

Do we have a milestone or GH Project that we can add this issue to and put it on HOLD?

I think closing it is also reasonable - this has been a known problem for a very long time 🤷‍♂️

[perunt]

we don't have a specific GH Project to tackle this issue directly. In V1 of comment linking, we use FlatList, which caused the same virtualization problem mentioned here. But in V2, we're planning to switch to WishList, and that should sort things out. The only problem is we don't have a set date for when WishList will be ready since it's still in the final stages of development and polishing.

[flaviadefaria]

@perunt @roryabraham I'll assign this to you then. Feel free to keep it open, with the correct priority, if it makes sense or close it.

[melvin-bot]

@roryabraham @perunt this issue was created 2 weeks ago. Are we close to a solution? Let's make sure we're treating this as a top priority. Don't hesitate to create a thread in #expensify-open-source to align faster in real time. Thanks!

[roryabraham]

Going to put this on HOLD for the comment linking project. I don't think it will necessarily be directly addressed by anything planned for the comment linking project, but this issue is a prerequisite for fixing this, so it makes sense to put this on HOLD

[roryabraham]

Long-term I kind of think some form of eviction from the Onyx cache would be a way to solve this. i.e: once we have bidirectional pagination implemented, then we can drop reportActions from the Onyx cache and fetch them back page-by-page from the disk.

WishList might help but I do think that larger and larger chats will lead to longer and longer initial load times, even for WishList

[roryabraham]

on HOLD

[roryabraham]

on HOLD

[roryabraham]

no update

[perunt]

@kavimuru, could you please test it again? Recently, a few PRs were merged, which removed the old hack with the list in WEB and added some optimization. So, it should be way better now.

[roryabraham]

requested retest: https://expensify.slack.com/archives/C9YU7BX5M/p1703268042698819

[roryabraham]

This issue can no longer be reproduced, closing this out 🎉

[Talha345]

@roryabraham would this issue be eligible for the reporting bonus as this was quite a peculiar bug?

Thanks!