Bug 231603

Summary:	[ iOS ] fast/scrolling/ios/reconcile-layer-position-recursive.html is a flaky failure
Product:	WebKit	Reporter:	ayumi_kojima
Component:	Scrolling	Assignee:	Nobody <webkit-unassigned>
Status:	NEW ---
Severity:	Normal	CC:	simon.fraser, webkit-bot-watchers-bugzilla, webkit-bug-importer
Priority:	P2	Keywords:	InRadar
Version:	WebKit Nightly Build
Hardware:	iPhone / iPad
OS:	Unspecified

Description ayumi_kojima 2021-10-12 12:03:10 PDT

fast/scrolling/ios/reconcile-layer-position-recursive.html

Is a flaky failure on iOS 15.

History: https://results.webkit.org/?suite=layout-tests&test=fast%2Fscrolling%2Fios%2Freconcile-layer-position-recursive.html

Result page: https://build.webkit.org/results/Apple-iOS-15-Simulator-Release-WK2-Tests/r283979%20(142)/results.html#

Diff:

--- /Volumes/Data/worker/ios-simulator-15-release-tests-wk2/build/layout-test-results/fast/scrolling/ios/reconcile-layer-position-recursive-expected.txt
+++ /Volumes/Data/worker/ios-simulator-15-release-tests-wk2/build/layout-test-results/fast/scrolling/ios/reconcile-layer-position-recursive-actual.txt
@@ -1,15 +1,15 @@
 (GraphicsLayer
   (anchor 0.00 0.00)
   (bounds 800.00 1621.00)
-  (visible rect 0.00, 1021.00 800.00 x 600.00)
-  (coverage rect 0.00, 1021.00 800.00 x 600.00)
+  (visible rect 0.00, 1020.50 800.00 x 600.00)
+  (coverage rect 0.00, 1020.50 800.00 x 600.00)
   (intersects coverage rect 1)
   (contentsScale 2.00)
   (children 1
     (GraphicsLayer
       (bounds 800.00 1621.00)
       (contentsOpaque 1)
-      (visible rect 0.00, 1021.00 800.00 x 600.00)
+      (visible rect 0.00, 1020.50 800.00 x 600.00)
       (coverage rect 0.00, 765.00 1056.00 x 856.00)
       (intersects coverage rect 1)
       (contentsScale 2.00)
@@ -22,15 +22,15 @@
           (position 8.00 1008.00)
           (bounds 300.00 300.00)
           (drawsContent 1)
-          (visible rect 0.00, 13.00 300.00 x 287.00)
+          (visible rect 0.00, 12.50 300.00 x 287.50)
           (coverage rect -8.00, -243.00 1056.00 x 856.00)
           (intersects coverage rect 1)
           (contentsScale 2.00)
           (children 1
             (GraphicsLayer
               (bounds 300.00 300.00)
-              (visible rect 0.00, 13.00 300.00 x 287.00)
-              (coverage rect 0.00, 13.00 300.00 x 287.00)
+              (visible rect 0.00, 12.50 300.00 x 287.50)
+              (coverage rect 0.00, 12.50 300.00 x 287.50)
               (intersects coverage rect 1)
               (contentsScale 2.00)
               (children 1
@@ -38,8 +38,8 @@
                   (anchor 0.00 0.00)
                   (bounds 300.00 510.00)
                   (drawsContent 1)
-                  (visible rect 0.00, 13.00 300.00 x 287.00)
-                  (coverage rect 0.00, 12.00 300.00 x 288.00)
+                  (visible rect 0.00, 12.50 300.00 x 287.50)
+                  (coverage rect 0.00, 12.50 300.00 x 287.50)
                   (intersects coverage rect 1)
                   (contentsScale 2.00)
                   (children 1
@@ -48,7 +48,7 @@
                       (bounds 210.00 410.00)
                       (drawsContent 1)
                       (visible rect 0.00, 0.00 210.00 x 250.00)
-                      (coverage rect -50.00, -38.00 300.00 x 288.00)
+                      (coverage rect -50.00, -37.50 300.00 x 287.50)
                       (intersects coverage rect 1)
                       (contentsScale 2.00)
                       (children 1
@@ -72,13 +72,13 @@
                               (contentsScale 2.00)
                               (children 2
                                 (GraphicsLayer
-                                  (position 7.00 28.00)
-                                  (approximate position 7.00 28.00)
+                                  (position 7.00 27.50)
+                                  (approximate position 7.00 27.50)
                                   (bounds 110.00 110.00)
                                   (contentsOpaque 1)
                                   (drawsContent 1)
                                   (visible rect 0.00, 0.00 110.00 x 110.00)
-                                  (coverage rect -7.00, -28.00 200.00 x 245.00)
+                                  (coverage rect -7.00, -27.50 200.00 x 245.00)
                                   (intersects coverage rect 1)
                                   (contentsScale 2.00)
                                   (children 1
@@ -89,7 +89,7 @@
                                       (contentsOpaque 1)
                                       (drawsContent 1)
                                       (visible rect 0.00, 0.00 110.00 x 110.00)
-                                      (coverage rect -62.00, -83.00 200.00 x 245.00)
+                                      (coverage rect -62.00, -82.50 200.00 x 245.00)
                                       (intersects coverage rect 1)
                                       (contentsScale 2.00)
                                     )

Comment 1 Radar WebKit Bug Importer 2021-10-12 12:04:38 PDT

<rdar://problem/84160039>

Comment 2 ayumi_kojima 2021-10-12 12:09:12 PDT

Marked test expectations https://trac.webkit.org/changeset/284001/webkit

Comment 3 ayumi_kojima 2021-10-15 15:36:50 PDT

I was not able to reproduce the failure locally on iOS 15 simulator using run-webkit-tests --force --ios-simulator --iterations 500 --exit-after-n-failures 1 fast/scrolling/ios/reconcile-layer-position-recursive.html