1613143 - webrender can send empty transaction when parent doesn't have child's display list

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, defect)

Comment 1

[Timothy Nikkel (:tnikkel)]

Attachment: Bug 1613143. Don't allow an empty transaction to succeed with webrender if we haven't sent a display list to the parent. r?mattwoodrow

I think this probably only shows up with fission oop iframes, tabs probably avoid this path.

The problem occurs when we reconstruct the containing iframe for a style change, we briefly hide the child document, clearing the display list on the parent via ClearCachedResources. Then show it again, we attempt an empty transaction and this succeeds because there is nothing to stop it. (The non-wr case fails because the layer contents are missing and that causes the empty transaction to fail.)

So keep track if we have sent a display list to the parent to allow/disallow an empty transaction.

This fixes a couple webrender+fission reftest failures but it's also a general rendering bug in webrender+fission reproducible in a regular browser.

Comment 2

[Chris Peterson [:cpeterson]]

Tracking R-fis bugs for Fission Nightly (M6)

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/d46cb79a9b55
Don't allow an empty transaction to succeed with webrender if we haven't sent a display list to the parent. r=mattwoodrow

Comment 4

[Andrei Ciure[:aciure]]

Backed out changeset d46cb79a9b55 (bug 1613143)for causing reftest fission failures
https://hg.mozilla.org/integration/autoland/rev/1a94989cf63b3f3e51f8cfbf0c7e452a0175128f

push that caused the backout: https://hg.mozilla.org/integration/autoland/rev/d46cb79a9b5504bdbb1f32ff5c6b9e68889b9812

failure: https://treeherder.mozilla.org/#/jobs?repo=autoland&resultStatus=testfailed%2Cbusted%2Cexception&classifiedState=unclassified&searchStr=linux%2C18.04%2Cx64%2Cquantumrender%2Cdebug%2Creftests%2Cwith%2Cfission%2Cenabled%2Ctest-linux1804-64-qr%2Fdebug-reftest-fis-e10s-8%2Cr-fis%28r8%29&fromchange=4d12f98d7eb486a28bd5aea3aa2c4adef9c59cbc&tochange=e188f8d308078010981f61d7a36d6ff089d0900c

Comment 5

[Timothy Nikkel (:tnikkel)]

It's unexpected pass in a test I expect it to fix. I'll just mark it as random with fission for now because I don't know which of all my fission patches are required exactly to make it pass consistently, when all of my patches land I'll remove the annotation.

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/1012d4dab45b
Don't allow an empty transaction to succeed with webrender if we haven't sent a display list to the parent. r=mattwoodrow

Comment 7

[Cristina Coroiu [:ccoroiu]]

https://hg.mozilla.org/mozilla-central/rev/1012d4dab45b