Bug 230857 - [ iOS 14 & 15 ] fast/images/image-subsampling.html is a flaky image failure
Summary: [ iOS 14 & 15 ] fast/images/image-subsampling.html is a flaky image failure
Status: NEW
Alias: None
Product: WebKit
Classification: Unclassified
Component: Images (show other bugs)
Version: WebKit Nightly Build
Hardware: iPhone / iPad Unspecified
: P2 Normal
Assignee: Nobody
Keywords: InRadar
Depends on:
Reported: 2021-09-27 13:58 PDT by ayumi_kojima
Modified: 2021-09-29 15:39 PDT (History)
7 users (show)

See Also:

Image diff (9.02 KB, image/png)
2021-09-27 13:59 PDT, ayumi_kojima
no flags Details

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Description ayumi_kojima 2021-09-27 13:58:04 PDT

Is a flaky image failure on iOS (both iOS 14 and iOS 15). The test failure is mainly seen on Release, but it also seen on Debug.

History: https://results.webkit.org/?suite=layout-tests&test=fast%2Fimages%2Fimage-subsampling.html

Result page: https://build.webkit.org/results/Apple-iOS-14-Simulator-Release-WK2-Tests/r283111%20(3394)/results.html
Comment 1 Radar WebKit Bug Importer 2021-09-27 13:58:32 PDT
Comment 2 ayumi_kojima 2021-09-27 13:59:26 PDT
Created attachment 439394 [details]
Image diff
Comment 3 ayumi_kojima 2021-09-27 14:07:42 PDT
Marked test expectations: https://trac.webkit.org/changeset/283133/webkit
Comment 4 ayumi_kojima 2021-09-29 12:06:54 PDT
I was not able to reproduce the image failure locally on iOS 14 simulator using run-webkit-tests --force --ios-simulator --iterations 100 --exit-after-n-failures 1 fast/images/image-subsampling.html. 

(The revision I tested was r281967. The failure has been seen for a while according to the history, so I should be able to reproduce with that revision if it was reproducible.)
Comment 5 Alexey Proskuryakov 2021-09-29 14:56:35 PDT
Actual image is missing the red square.

This seems almost impossible. Why would these work

ctx.fillStyle = "green"
ctx.fillStyle = "blue"

and ctx.fillStyle = "red" right before them not work?