Web Application fail to load properly every other time is launched

[Victor Tuson Palau]

I am testing a game called ninjaflips. Works fine the first time you launch it , but the second time wont load correctly. If you close it and try again it will launch fine and so on..

Attached logs for working and not working plus click package

[Victor Tuson Palau (vtuson)]

app log when failing to load

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Olivier Tilloy (osomon)]

Those two lines, from the failed log, seem to be relevant:

    [0828/103105:ERROR:cache_creator.cc(125)] Unable to create cache
    [0828/103105:ERROR:appcache_storage_impl.cc(1819)] Failed to open the appcache diskcache.

[Olivier Tilloy (osomon)]

Following up discussion on IRC with Alex and Bill, there was a suspicion that this problem might be linked to the use of the SessionStorage object in the webapp container. I discarded this hypothesis by commenting out all SessionStorage-related code in WebApp.qml and verifying that the app still runs fine only every other time.

[Bill Filler (bfiller)]

Note the MR linked in this bug should no longer be linked as it doesn't address this issue.

[Bill Filler (bfiller)]

The MR should be linked to this bug:
https://bugs.launchpad.net/webapps-core/+bug/1372243

[Chris Coulson (chrisccoulson)]

This breaks because disk_cache::VerifyStats() fails the signature check for the cache stats (the actual signature appears to be all zeroes, which might suggest that the stats aren't ever serialized to disk. This happens in 2 places - on a 30 second timer and during shutdown).

How are applications stopped when you swipe them away in the app switcher?

[Chris Coulson (chrisccoulson)]

Fixed with http://bazaar.launchpad.net/~oxide-developers/oxide/oxide.trunk/revision/769

[Olivier Tilloy (osomon)]

> How are applications stopped when you swipe them away
> in the app switcher?

QtMir calls ubuntu_app_launch_stop_application(…), which calls into Upstart’s D-Bus Stop method.

[Chris Coulson (chrisccoulson)]

Thanks, although I'm still not entirely clear. I should rephrase my question :)

Is the application given a chance to shut down cleanly (ie, the destructors for things like the QCoreApplication and any QQmlEngines run), or is it just killed? This bug would suggest either the latter, or resources not being cleaned up properly (which would sync the application cache to disk and would have prevented this problem)

[Olivier Tilloy (osomon)]

I’m not sure how exactly upstart’s Stop() method is implemented, but from my observations swiping an application away from the app switcher doesn’t give it a chance to shut down cleanly, i.e. it is killed. Which explains the issue.