977297 - Investigate unnecessary reflows and jank

Status: RESOLVED WONTFIX

(Marketplace Graveyard :: Code Quality, defect, P2)

Description

[Wil Clouser [:clouserw]]

http://paulrouget.com/e/fxoshud/ talks about how to watch for reflows and jank in apps and Dietrich tells me that the Marketplace is a particularly bad offender.

I don't have specific numbers we should be aiming for so this bug is about investigation:  spend some time with that tool comparing other apps to the marketplace and then evaluating things we can change to improve the marketplace.  Come back with quick fixes done and recommendations for anything that would take longer.  Working with a couple people here might improve results, also note Dietrich and Paul on the CC list - the resident experts if there are questions.

Comment 1

[Dietrich Ayala (:dietrich)]

I just did a quick pass with the Tarako device (128mb ram, single core cpu):

* Cold launch time almost 30 seconds on fast wifi. This needs investigation. I've seen it take a long time on Nexus 4 too.

* Generally memory seems to hold at 16mb. should aim for 10mb *max*, since we've got so little to work with.

* Peak memory 18mb - seems like some activity shortly after being loaded, and then also increases when installing an app

* List view is responsive once loaded, not too bad! IIRC scrolling this is where we saw a lot of reflows. Reducing them would improve responsiveness and reduce the CPU cost (battery life).

Comment 2

[Paul Rouget [:paul]]

After the marketplace has loaded, 49 reflows occured.
Scrolling doesn't trigger any reflow.
Clicking on "More" generates 50 reflows.
These reflows are interruptible (not triggered by JS) and very short. Basically, what you'd expect from a page load.

At startup, the app gets unresponsive for 3129ms, 1294ms and 294ms (long lag, medium lag, short lag). Then, while navigating, I see the same pattern again and again: long lag, medium lag, short lag (for example: 1648ms, 953ms, 123ms).

Might be interesting to see where these 3 lags come from.