1045430 - [Homescreen]sometimes homescreen showed a full-black wallpaper after switching camera to background

Status: RESOLVED WONTFIX

(Firefox OS Graveyard :: General, defect)

Description

[Danny Liang [:dliang]]

There is sometimes black screen/wallpapar issue when homescreen was killed.

STR:
1. keep as many apps at background at possible, then launching camera ;
2. take some photos, then press home button to get back homescreen;
3. sometimes there showed a full-black wallpaper.

Comment 1

[Danny Liang [:dliang]]

Hi Evelyn, could you have member to check the root cause?

Comment 2

[Ryan VanderMeulen [:RyanVM]]

Based on bug 1041963 comment 15, it sounds like this affects 1.4+.

Comment 3

[Evelyn Hung]

[Blocking Requested - why for this release]: we've had a quick fix on 1.3T, but the patch there can't be carry to this release (see bug 1041963 comment 15), so we need another fix for 1.4 and later releases.

@Luke, not sure if you have time to have a quick investigation here?

Comment 4

[Luke Chang [:lchang] (inactive)]

OK, I'll take a look soon.

Comment 5

[Luke Chang [:lchang] (inactive)]

I can't reproduce this bug on Dolphin by neither hand nor monkey test.

Therefore, I reverted the patch of bug 1041963 and tried to reproduce it on Tarako. I found the root cause is that a racing condition happens when system app get "mozmemorypressure" events. In the meantime, it has a chance to kill both homescreen app and music app simultaneously and will cause Window Mgmt fails to set correct active window.

Thus, the "edges" class remains in "screen" element in system app but homescreen app is set to be the current active app abnormally. For this reason, we'll see black background on the homescreen [1].

This symptom can be fixed by https://github.com/luke-chang/gaia/commit/0382f3c0f69a6314ecab13b2fe00ba7e4cb94f6a

However, I need more time to make sure it won't cause any regression. Despite this, the patch above still can't be involved in Dolphin since we don't have in-process homescreen and music apps in v1.4 branch.


[1] see https://github.com/mozilla-b2g/gaia/blob/v1.3t/apps/system/style/system/system.css#L343

Comment 6

[Luke Chang [:lchang] (inactive)]

(In reply to Luke Chang [:lchang] from comment #5)
> This symptom can be fixed by
> https://github.com/luke-chang/gaia/commit/0382f3c0f69a6314ecab13b2fe00ba7e4cb94f6a

Per offline discussion with Danny, this patch seems doesn't resolve the whole issue in bug 1041963. We may need someone to dig more information from Window Mgmt and Edge Gesture if necessary. (Since there is already a workaround, I don't think we need to find another patch at the moment.)

To resolve exactly this bug, however, we may need another STR to make investigation easier.

Comment 7

[Danny Liang [:dliang]]

(In reply to Luke Chang [:lchang] from comment #6)
> (In reply to Luke Chang [:lchang] from comment #5)
> > This symptom can be fixed by
> > https://github.com/luke-chang/gaia/commit/0382f3c0f69a6314ecab13b2fe00ba7e4cb94f6a
We still can see the issue with this patch on monkey test. 

> 
> Per offline discussion with Danny, this patch seems doesn't resolve the
> whole issue in bug 1041963. We may need someone to dig more information from
> Window Mgmt and Edge Gesture if necessary. (Since there is already a
> workaround, I don't think we need to find another patch at the moment.)
> 
> To resolve exactly this bug, however, we may need another STR to make
> investigation easier.

Agree, this issue is not easily to reproduce by manual, now the only way is by monkey test but not 100% reproduced. We will keep monitor it and try to find the STR.

Comment 8

[Wayne Chang [:wchang]]

Triage - minus until more consistently seen reproductions

Comment 9

[BMO Automation]

Firefox OS is not being worked on