161547 2016-09-02 13:57:57 -0700 REGRESSION: [mac-wk2 debug] LayoutTest tiled-drawing/scrolling/fixed/four-bars-zoomed.html is a flaky failure 2016-09-21 08:40:45 -0700 1 1 1 Unclassified WebKit WebKit Misc. WebKit Nightly Build Unspecified Unspecified NEW https://bugs.webkit.org/show_bug.cgi?id=105223 InRadar P2 Normal --- 1 ryanhaddad simon.fraser ap jonlee simon.fraser webkit-bug-importer oldest_to_newest 1225937 0 ryanhaddad 2016-09-02 13:57:57 -0700 LayoutTest tiled-drawing/scrolling/fixed/four-bars-zoomed.html is a flaky failure This test is a flaky failure on mac-wk2 debug bots https://build.webkit.org/builders/Apple%20Yosemite%20Debug%20WK2%20(Tests)/builds/14759 https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=tiled-drawing%2Fscrolling%2Ffixed%2Ffour-bars-zoomed.html --- /Volumes/Data/slave/yosemite-debug-tests-wk2/build/layout-test-results/tiled-drawing/scrolling/fixed/four-bars-zoomed-expected.txt +++ /Volumes/Data/slave/yosemite-debug-tests-wk2/build/layout-test-results/tiled-drawing/scrolling/fixed/four-bars-zoomed-actual.txt @@ -43,9 +43,9 @@ (coverage rect 0.00, 0.00 341.30 x 254.35) (intersects coverage rect 1) (contentsScale 2.30) - (tile cache coverage 0, 0 341 x 445) - (tile size 785 x 512) - (top left tile 0, 0 tiles grid 1 x 2) + (tile cache coverage 0, 0 445 x 445) + (tile size 512 x 512) + (top left tile 0, 0 tiles grid 2 x 2) (children 4 (GraphicsLayer (position -4.00 -4.00) 1227311 1 ryanhaddad 2016-09-07 13:06:19 -0700 First failure according to the dashboard is ~r204892, but that change itself seems unrelated. 1227752 2 ap 2016-09-08 13:54:45 -0700 <rdar://problem/28213422> 1228286 3 ryanhaddad 2016-09-09 12:04:38 -0700 Marked test as flaky in http://trac.webkit.org/projects/webkit/changeset/205758 1231981 4 ap 2016-09-20 22:44:08 -0700 I can reproduce this 100% by simply running the test alone: run-webkit-tests LayoutTests/tiled-drawing/scrolling/fixed/four-bars-zoomed.html Or, it reproduces 50 times like this: run-webkit-tests LayoutTests/tiled-drawing/scrolling/fixed/four-bars-zoomed.html --repeat 50 --no-retry -v --run-singly 1231982 5 ap 2016-09-20 22:44:51 -0700 The test has a 10 ms timer, which is never good in regression tests. 1231983 6 ap 2016-09-20 22:50:20 -0700 And if I change the timeout to 1000 ms, then the results are different yet. Simon, is logging tile sizes meaningful at all? Are there any common techniques for deflaking tests of this kind? 1232071 7 simon.fraser 2016-09-21 08:40:45 -0700 Seems like the test is racing with the tile-size timer. I wonder if we could turn off dumping of the tile caches for this test.