1197176 - Coming back to fennec from the task switcher sometimes doesn't repaint the content area

Status: VERIFIED FIXED

(Firefox for Android Graveyard :: Toolbar, defect)

Description

[Kartikaya Gupta (email:[e-mail])]

This seems to be happening pretty frequently on Fennec Nightly, possibly a regression from bug 1180295.

Start Fennec, load a page. Enter the android task switcher, and then re-enter Fennec. The content area is black, but as soon as you touch the screen it repaints correctly.

It looks like we're not requesting a composite when we come back to the foreground. Might be related to bug 1193753 although I can't reproduce that one and I can reproduce this one pretty consistently.

Comment 1

[Kartikaya Gupta (email:[e-mail])]

This seems to be very timing-specific. If I wait on the task switcher for a couple of seconds before re-entering Fennec I don't see the problem and everything looks good. If I re-enter Fenenc as soon as possible I see the chrome and content areas flash black and then sometimes the content area gets stuck in black.

Adding some logging seems to indicate that pausing the compositor (which happens synchronously from the java UI thread) is taking a while and if I restore Fennec before it's done I get the flashing/glitching. If I wait until the compositor pause is complete there's no issue.

Comment 2

[Kartikaya Gupta (email:[e-mail])]

Attachment: Patch

This seems to do the job.

Comment 3

[Kartikaya Gupta (email:[e-mail])]

(In reply to Kartikaya Gupta (email:[e-mail]) from comment #1)
> This seems to be very timing-specific.

For the record this timing-specific-ness seemed to amplified on my local debug build. On the Nightly build I don't think I could resume fennec fast enough to hit this. However on Nightly I noticed that on some pages the issue would reproduce consistently with a scroll offset of 0 but as soon as the page was scrolled even a little bit it wouldn't reproduce. No idea what's going on but the patch fixes it on my local debug build so I'm hoping it'll fix it on Nightly also.

Comment 4

[James Willcox (:snorp) ([e-mail]) (he/him)]

Comment on attachment 8651016 [details] [diff] [review]
Patch

Review of attachment 8651016 [details] [diff] [review]:
-----------------------------------------------------------------

Very weird....a SurfaceView shouldn't really be doing anything itself as far as drawing goes. It just handles positioning and sizing for a Surface which the surfaceflinger paints.

Comment 5

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/07e73fa84838

Comment 6

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/07e73fa84838

Comment 7

[Kartikaya Gupta (email:[e-mail])]

Comment on attachment 8651016 [details] [diff] [review]
Patch

Approval Request Comment
[Feature/regressing bug #]: according to the discussion on bug 1193753, there was probably a pre-existing issue in the code (since forever) that was exposed by bug 1143575.
[User impact if declined]: according to the discussion on bug 1193753, uplifting this may fix a problem with a black screen showing up when closing the settings in fenenc
[Describe test coverage new/current, TreeHerder]: not much but it's a small patch that can't really hurt
[Risks and why]: low risk. worst case we do an extra composite when it's not needed
[String/UUID change made/needed]: none

Comment 8

[Sylvestre Ledru [:Sylvestre]]

Comment on attachment 8651016 [details] [diff] [review]
Patch

OK, let's try it. We have time to fix potential fall out. Thanks

Comment 9

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-aurora/rev/9bd80eff00dd

Comment 12

[Ritu Kothari (:ritu) (Inactive, please n-i to RyanVM, jcristau, or pascal)]

Kartikaya, bug 1154732 was resolved dup of this issue. Given that this bug also impacts FF41, could you please request uplift to Beta? The patch looks fairly safe and simple.

Comment 13

[Ritu Kothari (:ritu) (Inactive, please n-i to RyanVM, jcristau, or pascal)]

Moving the FF41 tracking flag from bug 1154732 to here.

Comment 14

[Kartikaya Gupta (email:[e-mail])]

I'm not at all convinced that bug 1154732 is a dup of this, and I requested verification on that bug. However this patch is trivial and we can request an uplift to beta regardless.

Comment 15

[Kartikaya Gupta (email:[e-mail])]

Comment on attachment 8651016 [details] [diff] [review]
Patch

Approval Request Comment
(see comment 7 and comment 12)

Comment 16

[Ritu Kothari (:ritu) (Inactive, please n-i to RyanVM, jcristau, or pascal)]

Comment on attachment 8651016 [details] [diff] [review]
Patch

Patch has been in Nightly for a while, seems safe to uplift to Beta41 as it's a one-liner.

Comment 17

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/releases/mozilla-beta/rev/fe004d290a87

Comment 18

[Flaviu Cos]

Verified as fixed in builds:
43.0a1 2015-09-03;
42.0a2 2015-09-03;
Device: Asus Transformer Pad (Android 4.2.1).

Comment 19

[Flaviu Cos]

Verified as fixed in build 41 Beta 8;
Device: Asus Transformer Pad (Android 4.2.1).