High res gallery images are fetched on app restart causing poor performance - switch to lazily fetching high res gallery images
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	Mhurd
	Jul 19 2016, 11:09 PM

Description

This is ultimately fallout from the WKWebView update - had to change how we dealt with saved pages images pretty drastically.

Repro:

checkout 5.0.4
clean install to simulator
start at obama, save the article,
go back through previous 8 presidents saving them as well
stop app
checkout 5.0.5
start charles proxy
run 5.0.5 on top of old 5.0.4 data

For the steps above charles proxy indicated that, on startup...

403 images were fetched
75 image info queries were sent
~511 MB of data was transferred

Proposed fix:

on save only save MWKArticle's "imageURLsForSaving" (these are all the images the article actually used at the resolution it used them) and let the gallery lazily fetch 1280px high res images only when that image is actually displayed in gallery

Extra credit:

consolidate image info queries - run one query passing it list of all images we're wanting info about instead of doing separate query for each image

Related Objects
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		Status	Subtype	Assigned	Task
		Resolved		• Fjalapeno	T140845 High res gallery images are fetched on app restart causing poor performance - switch to lazily fetching high res gallery images
		Resolved		Mhurd	T140854 WKWebView fallout - need to handle TIF image thumbnail syntax and do audit/fix for any other type-specific thumbnail syntax

Event Timeline

Mhurd created this task.Jul 19 2016, 11:09 PM

Restricted Application added subscribers: Zppix, Aklapper. · View Herald TranscriptJul 19 2016, 11:09 PM

Mhurd added a subtask: T140854: WKWebView fallout - need to handle TIF image thumbnail syntax and do audit/fix for any other type-specific thumbnail syntax.Jul 20 2016, 12:36 AM

Mhurd updated the task description. (Show Details)Jul 20 2016, 12:39 AM

More numbers for "enwiki > San francisco" article on clean install:

5.0.4
pre save 15 images @ 492KB
post save 175 images @ 22MB
post restart 205 images @ 98.8MB

5.0.5
pre save 15 images @ 492KB
post save 128 images (smaller 'cause we're not fetching unused srcset variants any more!) @ 20.1 MB
post restart 153 images @ 91.2 MB

( Note: these numbers are for images appearing in SDWebImage's cache folder - "com.hackemist.SDWebImageCache.default" )

Mhurd renamed this task from 5.0.5 Saved pages startup sync is refetching large amount of images to 5.0.5 Saved pages startup sync is refetching large amount of images - switch to lazily fetching high res images.Jul 22 2016, 9:30 PM

Mhurd updated the task description. (Show Details)

Mhurd renamed this task from 5.0.5 Saved pages startup sync is refetching large amount of images - switch to lazily fetching high res images to High res gallery images are fetched on at app restart causing poor performance - switch to lazily fetching high res gallery images.Jul 22 2016, 9:32 PM

Mhurd renamed this task from High res gallery images are fetched on at app restart causing poor performance - switch to lazily fetching high res gallery images to High res gallery images are fetched on app restart causing poor performance - switch to lazily fetching high res gallery images.

Mhurd updated the task description. (Show Details)

MBinder_WMF added a project: iOS-app-feature-Performance.Jul 25 2016, 7:19 PM

@Mhurd is this still the case? I know we changed caching stuff a couple times, so just want to conifrm if this is still needed and or merged.

• JMinor triaged this task as Medium priority.Jul 25 2016, 7:22 PM

• JMinor moved this task from Needs Triage to Engineering Backlog on the Wikipedia-iOS-App-Backlog board.

@JMinor yes this is still the case. the image caching bits are *much* more sane than formerly, however, the high res images are not being fetched lazily and are indeed only fetched on app restart, which basically grinds everything to a halt the next time you restart the app if you're on a slower network :(

• JMinor closed subtask T140854: WKWebView fallout - need to handle TIF image thumbnail syntax and do audit/fix for any other type-specific thumbnail syntax as Resolved.Jul 26 2016, 11:08 PM

• Fjalapeno claimed this task.Aug 2 2016, 4:59 PM

• Fjalapeno added a project: iOS-app-v5.0.6-Hotfix.

• Fjalapeno moved this task from Tasks from Product Backlog to Needs Code Review on the iOS-app-v5.0.6-Hotfix board.

JoeWalsh mentioned this in rAPIOSba5930732e5c: Merge pull request #811 from wikimedia/feature/T140845/no-gallery-download.Aug 2 2016, 8:03 PM

• Fjalapeno moved this task from Needs Code Review to Ready for PM Signoff on the iOS-app-v5.0.6-Hotfix board.Aug 2 2016, 9:42 PM

• JMinor closed this task as Resolved.Aug 11 2016, 6:31 PM