1645122 - Intermittent image/test/reftest/jpeg/webcam-simulacrum.mjpg == image/test/reftest/jpeg/blue.jpg | image comparison, max difference: 224, number of differing pixels: 799999

Status: RESOLVED FIXED

(Core :: Graphics: ImageLib, defect)

Description

[Treeherder Bug Filer]

Filed by: rmaries [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer.html#?job_id=305950490&repo=autoland
Full log: https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/FnHi0npYSiK3CO0VVREf1w/runs/0/artifacts/public/logs/live_backing.log
Reftest URL: https://hg.mozilla.org/mozilla-central/raw-file/tip/layout/tools/reftest/reftest-analyzer.xhtml#logurl=https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/FnHi0npYSiK3CO0VVREf1w/runs/0/artifacts/public/logs/live_backing.log&only_show_unexpected=1

---

Comment 1

[Intermittent Failures Robot]

8 failures in 5211 pushes (0.002 failures/push) were associated with this bug in the last 7 days.

Repository breakdown:

• autoland: 8

Platform breakdown:

• windows10-64-qr: 3
• windows10-64: 5

For more details, see:
https://treeherder.mozilla.org/intermittent-failures.html#/bugdetails?bug=1645122&startday=2020-06-08&endday=2020-06-14&tree=all

Comment 2

[Timothy Nikkel (:tnikkel)]

Anyone able to pull an approximate regression range for this from treeherder results?

Comment 3

[Timothy Nikkel (:tnikkel)]

Actually, this is probably bug 1641682. It landed on the 11th but was backed out, then relanded on the 14th late in the day, and the intermittent started on the 11th before stopping and then starting again on the 15th.

Comment 4

[Intermittent Failures Robot]

57 failures in 4035 pushes (0.014 failures/push) were associated with this bug in the last 7 days.

This is the #23 most frequent failure this week.

** This failure happened more than 30 times this week! Resolving this bug is a high priority. **

** Try to resolve this bug as soon as possible. If unresolved for 2 weeks, the affected test(s) may be disabled. **

Repository breakdown:

• autoland: 44
• try: 7
• mozilla-central: 6

Platform breakdown:

• windows10-64: 37
• windows10-64-shippable-qr: 5
• windows10-64-qr: 4
• windows10-64-shippable: 6
• windows7-32: 3
• windows10-aarch64: 1
• windows10-64-devedition: 1

For more details, see:
https://treeherder.mozilla.org/intermittent-failures.html#/bugdetails?bug=1645122&startday=2020-06-15&endday=2020-06-21&tree=all

Comment 5

[Timothy Nikkel (:tnikkel)]

Not bug 1641682. Get about the same amount of failures with bug 1641682 backed out.

Comment 6

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

Bug 1599160 landed at both starts and touches image loader.

Comment 7

[Emilio Cobos Álvarez (:emilio)]

Hmm, there's no stylesheets involved in those test-cases though. Only ImageDocument.css and TopLevelImageDocument.css, which don't load any image whatsoever... Plus the mjpg file is served with Cache-Control: no-cache.

Though I guess it could potentially make the "resource" URI for the image document fire the load event faster? The mjpg should block the load event anyhow... Aryx, is there a way to confirm that this is caused by bug 1599160? I'd find it a bit surprising / it'd seem it's a pre-existing bug if anything.

Comment 8

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

None of the retriggers reproduced the issue.

Comment 9

[Timothy Nikkel (:tnikkel)]

I've pushed a couple of try pushes checking asan reftests where I've been able to reproduce pretty easily to see if bug 1599160 is involved.

One thing to note about this test that is unlike almost every other reftest: the image is a multipart image and loading multipart images toplevel means we create a new (image) document for every frame/part of the multipart image.

Comment 10

[Timothy Nikkel (:tnikkel)]

Try results do strongly suggest that bug 1599160 is to blame. Using Windows Asan builds (which seem the most reliable for me)

0/19 failures with base revision 3ce9af6580b2748bd34837cb3d1aa074c6f76436 (changeset immediately before bug 1599160)
https://treeherder.mozilla.org/#/jobs?repo=try&revision=5fa54a13959beeec49640df043bfec7414d238ff

4/19 failures with base revision 419a897d7e4b9489ad51b51044f154e5bcbb605e (first with changeset with bug 1599160 landed)
https://treeherder.mozilla.org/#/jobs?repo=try&revision=092e01a3718f54c7f4bbc81586751d7a7640e1a9

Emilio is there logging we can turn on to maybe shed more light on this?

Comment 11

[Emilio Cobos Álvarez (:emilio)]

Attachment: Bug 1645122 - Properly block onload when coalescing loads with other documents. r=heycam,#style

If two loading documents hit the sheet cache and we coalesce the
resource load, there's nothing that prevents the load event on the
second document from firing right now, and there should be.

While at it, also fix the handling of the pending load count, though
it has no correctness impact on the particular test we're fixing here...

We were never decrementing it, which is of course wrong. However it
kinda ended up working because it just causes us to not defer more
loads.

The new assertions and responsibility of the counter should ensure it
stays correct.

Comment 12

[Emilio Cobos Álvarez (:emilio)]

(In reply to Timothy Nikkel (:tnikkel) from comment #9)

I've pushed a couple of try pushes checking asan reftests where I've been able to reproduce pretty easily to see if bug 1599160 is involved.

One thing to note about this test that is unlike almost every other reftest: the image is a multipart image and loading multipart images toplevel means we create a new (image) document for every frame/part of the multipart image.

So I loaded the reftest with MOZ_LOG=nsCSSLoader:5 and I saw them coalesce various loads across the ImageDocument.css. I dug a bit and I think we were not properly blocking onload for these, so I sent a patch to do that.

Tim, is there any chance you can confirm that patch fixes the issue?

Comment 13

[Timothy Nikkel (:tnikkel)]

Sure, I pushed it to try

https://treeherder.mozilla.org/#/jobs?repo=try&revision=9c079da2742f3c276ce5a9f404eb56d2d423de4c

a few retriggers should confirm.

Comment 14

[Intermittent Failures Robot]

17 failures in 843 pushes (0.02 failures/push) were associated with this bug yesterday.

Repository breakdown:

• mozilla-central: 3
• autoland: 13
• try: 1

Platform breakdown:

• windows10-64: 14
• windows7-32: 1
• windows10-64-qr: 1
• windows10-64-shippable: 1

For more details, see:
https://treeherder.mozilla.org/intermittent-failures.html#/bugdetails?bug=1645122&startday=2020-06-22&endday=2020-06-22&tree=all

Comment 15

[Timothy Nikkel (:tnikkel)]

I confirm that your patch looks to fix the problem on my try push. Thanks!

Comment 16

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/d07d66ecd6b9
Properly block onload when coalescing loads with other documents. r=heycam

Comment 17

[Dorel Luca [:dluca]]

https://hg.mozilla.org/mozilla-central/rev/d07d66ecd6b9

Comment 18

[Intermittent Failures Robot]

23 failures in 5252 pushes (0.004 failures/push) were associated with this bug in the last 7 days.

Repository breakdown:

• mozilla-central: 5
• autoland: 15
• try: 3

Platform breakdown:

• windows10-64: 17
• windows7-32: 1
• windows10-64-qr: 2
• windows10-64-shippable: 1
• windows10-64-shippable-qr: 1
• windows7-32-shippable: 1

For more details, see:
https://treeherder.mozilla.org/intermittent-failures.html#/bugdetails?bug=1645122&startday=2020-06-22&endday=2020-06-28&tree=all