Bug 46662 – CrashTracer: 1,803 crashes in Safari at com.apple.WebCore: -[AccessibilityObjectWrapper accessibilityIsIgnored] + 56

• Status: RESOLVED
• Resolution: FIXED
• Component: Accessibility

[chris fleizach]

54 com.apple.WebCore:  -[AccessibilityObjectWrapper accessibilityIsIgnored] + 56 <==
        54 com.apple.AppKit:  NSAccessibilityPostNotificationForObservedElement + 99
          54 com.apple.WebCore:  WebCore::AXObjectCache::postPlatformNotification + 234
            54 com.apple.WebCore:  WebCore::AXObjectCache::notificationPostTimerFired + 76
              54 com.apple.WebCore:  WebCore::ThreadTimers::sharedTimerFiredInternal + 151
                54 com.apple.WebCore:  WebCore::timerFired + 53
                  54 com.apple.CoreFoundation:  __CFRunLoopRun + 6488
                    54 com.apple.CoreFoundation:  CFRunLoopRunSpecific + 575
                      54 com.apple.HIToolbox:  RunCurrentEventLoopInMode + 333
                        49 com.apple.HIToolbox:  ReceiveNextEventCommon + 310
                        | 49 com.apple.HIToolbox:  BlockUntilNextEventMatchingListInMode + 59
                        |   49 com.apple.AppKit:  _DPSNextEvent + 708
                        |     49 com.apple.AppKit:  -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 155
                        |       49 com.apple.Safari:  -[BrowserApplication nextEventMatchingMask:untilDate:inMode:dequeue:]
                        |         47 com.apple.AppKit:  -[NSApplication run] + 395
                        |         | 47 com.apple.AppKit:  NSApplicationMain + 364
                        |         |   47 com.apple.Safari:  start
                        |         pruning: 1 com.apple.AppKit:  -[NSScroller trackKnob:] + 1959
                        |         pruning: 1 com.apple.AppKit:  -[NSScrollView scrollWheel:] + 711
                        pruning: 5 com.apple.HIToolbox:  ReceiveNextEventCommon + 148

[chris fleizach]

The problem is that when posting a notification after a timer callback, an updateLayout can be called which invalidates the object that initiated the updateLayout.

[chris fleizach]

rdar://8203386

[chris fleizach]

Created attachment 68984 [details]
patch

[Beth Dakin]

Comment on attachment 68984 [details]
patch

Awesome! I don't love the name prepareAccessibilityMethod, but I'm not sure I have a better suggestion. What about something like updateObjectBackingStore? Is that too specific? Anyway, I don't think the title *needs* to change, but I thought I would mention it.

[chris fleizach]

we can go with updateObjectBackingStore

[chris fleizach]

http://trac.webkit.org/changeset/68461