308667 2026-02-25 13:21:43 -0800 [iOS] webanimations/threaded-animations/scroll-timeline-root-scroller.html is a flaky text failure 2026-03-13 16:31:53 -0700 1 1 1 Unclassified WebKit Animations WebKit Nightly Build Unspecified Unspecified RESOLVED FIXED InRadar P2 Normal --- 1 d_delatoba d_delatoba graouts webkit-bot-watchers-bugzilla webkit-bug-importer oldest_to_newest 2184926 0 d_delatoba 2026-02-25 13:21:43 -0800 webanimations/threaded-animations/scroll-timeline-root-scroller.html is a flaky text failure on both release and debug however, release flakes do not show on bots and are extremely flaky. HISTORY: https://results.webkit.org/?suite=layout-tests&test=webanimations%2Fthreaded-animations%2Fscroll-timeline-root-scroller.html&platform=ios&recent=false&style=debug&recent=false DIFF: https://build.webkit.org/results/Apple-iOS-26-Simulator-Debug-WK2-Tests/308173%40main%20(779)/webanimations/threaded-animations/scroll-timeline-root-scroller-pretty-diff.html DIFF URL: --- /Volumes/Data/worker/Apple-iOS-26-Simulator-Debug-WK2-Tests/build/layout-test-results/webanimations/threaded-animations/scroll-timeline-root-scroller-expected.txt +++ /Volumes/Data/worker/Apple-iOS-26-Simulator-Debug-WK2-Tests/build/layout-test-results/webanimations/threaded-animations/scroll-timeline-root-scroller-actual.txt @@ -1,3 +1,3 @@ -PASS The timeline current time updates as its source is scrolled with a root scroller +FAIL The timeline current time updates as its source is scrolled with a root scroller assert_equals: After scrolling to 700, the timeline time is 50.00% expected "50.00%" but got "0.00%" REPRODUCTION: I was able to reproduce this on iOS 26.2 debug and release ToT with the following: Release: run-webkit-tests --no-build --no-retry --no-show-results --exit-after-n-failures=1 --expect-pass --iterations=2000 --force -f --clobber-old-results --ios-simulator --release webanimations/threaded-animations/scroll-timeline-root-scroller.html --udid < 3 udids > Debug: run-webkit-tests --no-build --no-retry --no-show-results --exit-after-n-failures=1 --expect-pass --iterations=1000 --force --clobber-old-results --ios-simulator --debug webanimations/threaded-animations/scroll-timeline-root-scroller.html I am going to mark expectations as pass fail while this pends investigation. 2184927 1 webkit-bug-importer 2026-02-25 13:22:06 -0800 <rdar://problem/171197721> 2184930 2 d_delatoba 2026-02-25 13:25:50 -0800 Pull request: https://github.com/WebKit/WebKit/pull/59446 2184931 3 ews-feeder 2026-02-25 13:27:43 -0800 Test gardening commit 308231@main (0733cc3c8b6c): <https://commits.webkit.org/308231@main> Reviewed commits have been landed. Closing PR #59446 and removing active labels. 2184995 4 d_delatoba 2026-02-25 16:36:45 -0800 This could be a test issue where one UIHelper.renderingUpdate() is not sufficient since it waits for a local animation frame + setTimeout in the web process but may not guarantee the UI process has handled the scroll thus resulting in the test not receiving a scroll. This is also supported by the fact that this is much flakier when running at high cpu usage and debug. Adding another UIHelper.renderingUpdate() allows the test to pass all iterations - even in parallel so I am going to put this fix up as a pr. But I do think it's worth mentioning this could be masking an actual WebKit issue where timeline updates are not happening when they should. 2185002 5 d_delatoba 2026-02-25 16:46:10 -0800 Pull request: https://github.com/WebKit/WebKit/pull/59461 2190158 6 ews-feeder 2026-03-13 16:31:51 -0700 Committed 309241@main (f8885281fecb): <https://commits.webkit.org/309241@main> Reviewed commits have been landed. Closing PR #59461 and removing active labels.