RESOLVED FIXED 216591
REGRESSION(r266677): ASSERTION FAILED in PaintFrequencyTracker::end() 
https://bugs.webkit.org/show_bug.cgi?id=216591
Summary REGRESSION(r266677): ASSERTION FAILED in PaintFrequencyTracker::end()
Said Abou-Hallawa
Reported 2020-09-15 17:03:14 PDT
Painting RenderLayers can be called from code paths which do not schedule RenderingUpdate through RenderingUpdateScheduler. This means RenderLayer::paintLayerContents() may be called while Page::updateRendering() is not on the call stack. This will make timestampForPaintFrequencyTracking() returns zero in this case. So PaintFrequencyTracker::end() will fail the assertion ASSERT(m_firstPaintTime). An example for this case is taking a snapshot of the page, or calling FrameView::paintContentsForSnapshot(). Another example is updating control tints or calling FrameView::updateControlTints().
Attachments
Patch (8.68 KB, patch)
2020-09-15 17:54 PDT, Said Abou-Hallawa 		simon.fraser: review+
DetailsFormatted DiffDiff
Patch (9.15 KB, patch)
2020-09-15 19:03 PDT, Said Abou-Hallawa 		no flags
DetailsFormatted DiffDiff
Patch (8.81 KB, patch)
2020-09-15 21:27 PDT, Said Abou-Hallawa 		no flags
DetailsFormatted DiffDiff
Show Obsolete (1) View All Add attachment proposed patch, testcase, etc.
Wenson Hsieh
Comment 1 2020-09-15 17:32:14 PDT
(In reply to Said Abou-Hallawa from comment #0) > Painting RenderLayers can be called from code paths which do not schedule > RenderingUpdate through RenderingUpdateScheduler. This means > RenderLayer::paintLayerContents() may be called while > Page::updateRendering() is not on the call stack. This will make > timestampForPaintFrequencyTracking() returns zero in this case. So > PaintFrequencyTracker::end() will fail the assertion > ASSERT(m_firstPaintTime). An example for this case is taking a snapshot of > the page, or calling FrameView::paintContentsForSnapshot(). Another example > is updating control tints or calling FrameView::updateControlTints(). To clarify — `timestampForPaintFrequencyTracking()` will only return 0 if `Page::updateRendering()` has never been called (not if `RenderLayer::paintLayerContents()` is called while `Page::updateRendering()` is not on the call stack).
Said Abou-Hallawa
Comment 2 2020-09-15 17:54:47 PDT
Created attachment 408881 [details] Patch
Said Abou-Hallawa
Comment 3 2020-09-15 18:36:53 PDT
<rdar://problem/68635418>
Said Abou-Hallawa
Comment 4 2020-09-15 19:03:45 PDT
Created attachment 408885 [details] Patch
Said Abou-Hallawa
Comment 5 2020-09-15 21:27:00 PDT
Created attachment 408896 [details] Patch
EWS
Comment 6 2020-09-15 23:33:20 PDT
Committed r267137: <https://trac.webkit.org/changeset/267137> All reviewed patches have been landed. Closing bug and clearing flags on attachment 408896 [details].
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