126970 2014-01-14 01:57:04 -0800 [ATK] AXChildrenChanged notification handling is a performance black hole 2014-01-14 07:41:26 -0800 1 1 1 Unclassified WebKit WebKitGTK 528+ (Nightly build) Unspecified Unspecified RESOLVED FIXED P2 Normal --- 1 zan webkit-unassigned aboxhall apinheiro cfleizach commit-queue dmazzoni jcraig jdiggs mario samuel_white oldest_to_newest 967725 0 zan 2014-01-14 01:57:04 -0800 in AXObjectCache::postPlatformNotification, handling the AXChildrenChanged is causing great performace reduction when loading the single-page HTML Living Standard document. http://trac.webkit.org/browser/trunk/Source/WebCore/accessibility/atk/AXObjectCacheAtk.cpp#L196 http://www.whatwg.org/specs/web-apps/current-work/ 967726 1 zan 2014-01-14 01:58:53 -0800 Commenting out that code block reduces the time of load from 60 seconds down to 15 seconds. The ref-deref cycle is fired more than a million times during the load, and AccessibilityObject::updateBackingStore() is called twice per cycle, causing additional work that hinders the performance. 967727 2 221130 mario 2014-01-14 02:03:58 -0800 Created attachment 221130 Patch proposal This should be enough to fix this issue. Sorry for the issue in the first place (and thanks Zan for reporting it) 967778 3 221130 gustavo 2014-01-14 05:40:21 -0800 Comment on attachment 221130 Patch proposal View in context: https://bugs.webkit.org/attachment.cgi?id=221130&action=review > LayoutTests/accessibility/children-changed-sends-notification-expected.txt:12 > -PARAGRAPH notification: AXChildrenAdded > -GLOBAL notification: AXChildrenAdded on element with role AXRole: AXParagraph > PARAGRAPH notification: AXChildrenRemoved > GLOBAL notification: AXChildrenRemoved on element with role AXRole: AXParagraph > +PARAGRAPH notification: AXChildrenAdded > +GLOBAL notification: AXChildrenAdded on element with role AXRole: AXParagraph Does this not affect Mac? Is this test specific for ATK? 967816 4 221130 mario 2014-01-14 07:12:11 -0800 Comment on attachment 221130 Patch proposal (In reply to comment #3) > (From update of attachment 221130 [details]) > View in context: https://bugs.webkit.org/attachment.cgi?id=221130&action=review > > > LayoutTests/accessibility/children-changed-sends-notification-expected.txt:12 > > -PARAGRAPH notification: AXChildrenAdded > > -GLOBAL notification: AXChildrenAdded on element with role AXRole: AXParagraph > > PARAGRAPH notification: AXChildrenRemoved > > GLOBAL notification: AXChildrenRemoved on element with role AXRole: AXParagraph > > +PARAGRAPH notification: AXChildrenAdded > > +GLOBAL notification: AXChildrenAdded on element with role AXRole: AXParagraph > > Does this not affect Mac? Is this test specific for ATK? The mac is currently skipping this test, so yes, this test is specific to ATK. Thanks for the review! 967832 5 221130 commit-queue 2014-01-14 07:41:24 -0800 Comment on attachment 221130 Patch proposal Clearing flags on attachment: 221130 Committed r161966: <http://trac.webkit.org/changeset/161966> 967833 6 commit-queue 2014-01-14 07:41:26 -0800 All reviewed patches have been landed. Closing bug. 221130 2014-01-14 02:03:58 -0800 2014-01-14 07:41:24 -0800 Patch proposal 0001-ATK-AXChildrenChanged-notification-handling-is-a-per.patch text/plain 4881 mario RnJvbSBmNWI4MzhhNmM2MjRjM2RiYTgwNjJhYTRkZjAxN2VjY2Q1NmFhYWI4IE1vbiBTZXAgMTcg MDA6MDA6MDAgMjAwMQpGcm9tOiBNYXJpbyBTYW5jaGV6IFByYWRhIDxtYXJpby5wcmFkYUBzYW1z dW5nLmNvbT4KRGF0ZTogVHVlLCAxNCBKYW4gMjAxNCAxMDowMjoyMyArMDAwMApTdWJqZWN0OiBb UEFUQ0hdIFtBVEtdIEFYQ2hpbGRyZW5DaGFuZ2VkIG5vdGlmaWNhdGlvbiBoYW5kbGluZyBpcyBh CiBwZXJmb3JtYW5jZSBibGFjayBob2xlCiBodHRwczovL2J1Z3Mud2Via2l0Lm9yZy9zaG93X2J1 Zy5jZ2k/aWQ9MTI2OTcwCgotLS0KIExheW91dFRlc3RzL0NoYW5nZUxvZyAgICAgICAgICAgICAg ICAgICAgICAgICAgICAgIHwgICAxMyArKysrKysrKysrKysKIC4uLmhpbGRyZW4tY2hhbmdlZC1z ZW5kcy1ub3RpZmljYXRpb24tZXhwZWN0ZWQudHh0IHwgICAgNCArKy0tCiBTb3VyY2UvV2ViQ29y ZS9DaGFuZ2VMb2cgICAgICAgICAgICAgICAgICAgICAgICAgICB8ICAgMjEgKysrKysrKysrKysr KysrKysrKysKIC4uLi9XZWJDb3JlL2FjY2Vzc2liaWxpdHkvYXRrL0FYT2JqZWN0Q2FjaGVBdGsu 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