still trying to chase down Android choppy feed scrolling. added some instrumentation to the app — using React profiling builds and <Profiler> to track long render phases. we *do* have long tasks (presumably rendering offscreen story items as you scroll) but they’re on the JS thread. so why stutter? - ThreadSky

danabra.mov • 178 days ago

still trying to chase down Android choppy feed scrolling. added some instrumentation to the app — using React profiling builds and to track long render phases.

we *do* have long tasks (presumably rendering offscreen story items as you scroll) but they’re on the JS thread. so why stutter?

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jsjayfiled.bsky.social•178 days ago

Damn you for bringing it up. Can't unsee it now.
Hoping to hear about how this plays out like @t3.gg did with his Zed scrolling issue
https://www.perplexity.ai/search/did-theo-talk-about-getting-th-yC_cURoKSbKopFg9BZYcjQ#1

danabra.mov•178 days ago

i’m not sure i’ll actually find the cause :/

baxuz.bsky.social•177 days ago

https://bsky.app/profile/baxuz.bsky.social/post/3lb7lcvwj4k2t

Could this be related somehow?

arnorhs.dev•177 days ago

Nice, I hope you discover something great!

Genuinely hard problem domain on Android (I'm assuming also in RN). It's been tough to get smooth scrolling since the very first version of ListView.

astralphnx.bsky.social•178 days ago

I've been running into an issue with some images just crashing for me when I open them which gets fixed by cache clearing. I was wondering if deploying a dev build to my device would use the same cache as shipping so I could generate logs because I wanted to try file an issue report on that one

ajaymaurya.com•178 days ago

What do you use to render posts, flatlist, fladhlist or some custom component

vpon.me•178 days ago

Dan, is it possible to create private lists?

Also, I'm a bit confused, we have feeds and lists. Feeds are pre-created (?), I cannot create public feeds, right? While all my lists are public?

Btw, just made a test list, went to your profile and found out that you have the same one :)

danabra.mov•178 days ago

1. not possible

2. you can create feeds with third party tools (or via API) but not via main app for now

vpon.me•178 days ago

Understood.

Any reason for 1?

E.g. if I want to have a private list of people and see what they post about, is it a bad thing?

danabra.mov•178 days ago

no, we just haven’t built some prerequisites necessary for supporting this well

skillstopractice.com•178 days ago

Was pleasantly surprised to see how easy skyfeed seems to be for a no-code solution.

squorch.com•178 days ago

Jake-chinatown dot gif

danabra.mov•178 days ago

this is quite a headscratcher to me. the stutter does seem to roughly correlate to long JS thread renders. but not every long JS thread render leads to a stutter — in particular, if i start scrolling back upwards, there are still long JS thread tasks but the UI thread remains smooth. why?

aafkevultink.bsky.social•178 days ago

Werder Bremen is asking their 600.000 followers to join bsky. Might have caused you your hickup right there lol

aafkevultink.bsky.social•178 days ago

If I turn on the developpers tools here it mutters about metaname settings?

aafkevultink.bsky.social•178 days ago

I cant all off sudden use my smileys either so I suspect you might well be right that it is a JS settings thing. Don't emoji's usually reside in that pack too? Maybe their settings had an update? Hell what do I know, i be lucky if I get my own developpers tools to run the way that I want.

danabra.mov•178 days ago

maybe there’s something happening for the first time per each post? like something to do with images. so its timing matches the first time that post shows up, but doesn’t happen again when scrolling up? not sure. and not sure how to debug what’s going on with the UI thread.

shikasd.bsky.social•178 days ago

fwiw looking into this for a little bit right now
https://bsky.app/profile/shikasd.bsky.social/post/3lbbbzqvie22p

schier.co•178 days ago

Is it still slow if you delete all image components, to rule that out?

danabra.mov•178 days ago

will try that next. i tried that before and it didn’t seem to help but i have a more scientific setup now

danabra.mov•178 days ago

ok this time it does help a lot. welp

schier.co•178 days ago

Haha, the joy of programming

zachrip.bsky.social•178 days ago

Are full size images being decoded and uploaded to the gpu?

ricky.fm•178 days ago

Are you using flatlist? I know there’s a race condition there that will sometimes flush a ton of updates when you scroll (look at the thing called Batchinator

danabra.mov•178 days ago

anyway here’s the JS thread profiling PR https://github.com/bluesky-social/social-app/pull/6510

danabra.mov•178 days ago

and now it’s fast but i didn’t change anything 😭

coreh.bsky.social•178 days ago

A wild guess but could this be related to thread affinity and performance/efficiency cores?

Does RN leverage Android's Performance Hint API at all? The fact that it seems to appear and go away on its own could indicate that the default heuristics are not working great depending on load and thermals

rseymour.bsky.social•178 days ago

Contention eased by added profile latency?

douglowder.com•178 days ago

If this were an embedded system I’d say you added some code that got rid of the race condition

joshpayette.dev•177 days ago

lmao I felt that in my soul. Good luck!

bdbch.com•177 days ago

Are there specific devices that have issues with scrolling on feeds? My Pixel 6 just scrolls through my feeds fine without any stutters.

bidetofevil.wtf•178 days ago

Sorry if you already know this, but jank on Android is usually due to the main thread being too busy to display frames at the screen refresh rate or the render thread not producing them in time

Looking at the trace, the render thread is taking 20ms+ to draw a frame, so the display falls behind.

danabra.mov•178 days ago

ah fantastic. any way to dig into why the render thread is taking too long? i’m also seeing much longer stutters. it seems like i can narrow it down to images, but not sure yet

bidetofevil.wtf•178 days ago

Yeah, digging deeper for these ones, it's waiting forever on the GPU, sometime on a binder call (e.g. IPC to system services), sometimes the display hardware buffer composer (HWC).

You can see the CPU cores aren't even that busy - so it's just asking the display hardware to do too much.

bidetofevil.wtf•178 days ago

If you have the Perfetto trace, you can see exactly what the CPUs are doing, along with all the threads in the bsky process as well as others running at the same time

And you don't need to spin up an IDE to take the trace: you can take it right on your phone, and then open it up at https://ui.perfetto.dev

bidetofevil.wtf•178 days ago

Here are the instructions: https://developer.android.com/topic/performance/tracing/on-device

Perfetto can be configured to get even more data than the defaults. And what you'll likely find as root causes are resource contention and alloc limitations. Deep view trees are just hard for low end devices without some major tweaks.

bidetofevil.wtf•178 days ago

The path to optimization can be tricky, even if you're dealing with bare Android, let alone the indirection and added level of complexity that RN brings. But if anyone would know how, it's experts like @romainguy.dev, @nacholopez.dev, and the loads of other Android perf folks who are now here 😀

manhng132.bsky.social•178 days ago

Ohh may be so long time but is will done

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