Substituting wallpaper under mir produces blackout

[Allan LeSage]

Seeing that when when we change wallpaper (even 'Cancel') under mir, I'm led to a blackout; davmor2 reporting 100% CPU for system settings.

[Dave Morley (davmor2)]

So for me I go to change the walllpaper under mir while monitoring adb shells top

I got apport at 98.8% initially and then the following

 1657 phablet 20 0 279m 120m 51m S 99.2 17.3 5:04.69 system-settings

The screen is blank and the system unresponsive. This is on maguro.

On Surface Flinger the Background just changed.

[Sebastien Bacher (seb128)]

Thank you for your bug report, what the settings are doing is basically writting a gsettings config key, that unity is picking...
Could you

- give us the bug number from apport, that's likely a segfault (we need a good stacktrace on it, could you get one manually if the retracing doesn't work)?

- check on other devices? (I think somebody said, the other day on IRC, that the issue was specific to maguro)

- check what happens if you change the gsettings key by hand?
e.g
$ adb shell
$ su - phablet
$ gsettings set org.gnome.desktop.background picture-uri 'file:///directory/to/an/image.jpg'

[Allan LeSage (allanlesage)]

seb128 to your points above:

- Two crashes coincide with this settings hang: gallery-app reported as lp:1234767 , unity8 reported as lp:1234737 .
- Hang occurs on both mako (mine) and maguro (davmor2's).
- Setting manually as you describe has the effect of changing the wallpaper successfully, no hang.

[Sebastien Bacher (seb128)]

if unity8 is segfaulting, it could explain why the change doesn't get applied then, since unity is the process drawing the background...

[Ken VanDine (ken-vandine)]

When changing it from system-settings, there is a crossfade from the toolkit. Maybe that is triggering a crash?

[Allan LeSage (allanlesage)]

More to test here? To whom would we address the crossfade question? Asking b/c I don't know.

[Sebastien Bacher (seb128)]

the crossfade is a toolkit feature, so the sdk team most likely

[Ken VanDine (ken-vandine)]

You can test to see if crossfade is triggering it with qmlscene using this QML file. Just replace test1.png and test2.png to images that exist on the device.

[Allan LeSage (allanlesage)]

Ken's test behaves as expected; also having installed upstart-app-launch-tools at his direction, `upstart-app-launch gallery-app` does nothing, just get a warning: http://paste.ubuntu.com/6193234/ .

[Allan LeSage (allanlesage)]

Correction, with a fully-qualified login as phablet, gallery-app launch works properly.

[Allan LeSage (allanlesage)]

Per ted's request here are bustle logs from seb128's gsettings tweak above.

[Allan LeSage (allanlesage)]

This may be related to lp:1235195 , or at least someone's making the inference that unity8 is implicated over there?

Laney, kenvandine, seb128, what further can I test to 'complete' this bug for us?

[Allan LeSage (allanlesage)]

Persists in image 83 FWIW.

[Ken VanDine (ken-vandine)]

I attached 2 click packages that provide an importer and exporter for an image using content-hub. To test this, install both click packages and set the default source for pictures to the exporter example with gsettings.

sudo click install --force-missing-framework --user=$USER com.ubuntu.developer.ken-vandine.hub-importer_0.1_all.click
sudo click install --force-missing-framework --user=$USER com.ubuntu.developer.ken-vandine.hub-exporter_0.1_all.click
gsettings set com.ubuntu.content.hub.default pictures com.ubuntu.developer.ken-vandine.hub-exporter_hub-exporter_0.1

Search for "hub" in the applications scope, and launch "Hub Importer". Click on the "Import from default" button. You should see Hub Exporter launch and take focus. Click the "Export" button. The application won't close, so swipe to switch back to the Hub Importer app. You should see the ubuntuone-music icon displayed.

[Allan LeSage (allanlesage)]

Ken all as you describe in the script, the ubuntuone-music icon is displayed, even. I'm going to wait for a resolution to lp:1234609 (proposed cause of related lp:1235195 ) and test again.

[Iain Lane (laney)]

I don't think this is a problem any more, is it?

[Sebastien Bacher (seb128)]

the issue was not in system settings but in Mir not liking the gallery-app exiting iirc