When an application is suspended or closed it causes a large UI stutter

Bug #1518935 reported by Andrew Hayzen on 2015-11-23
This bug affects 17 people
Affects Status Importance Assigned to Milestone
Canonical System Image
Michał Sawicz
qtmir (Ubuntu)
ubuntu-app-launch (Ubuntu)
Ted Gould

Bug Description

When an application is suspended or closed it causes a large UI stutter.

What happened:
1) Open multiple applications (eg Browser and Music)
2) Switch from Browser to Music
3) Scroll up/down a listview
4) Around 2 seconds after switching from Browser to Music the process is suspended and it can be observed that a UI stutter occurs

What I expected to happen:
At step 4) for there to be no stutter in the UI

Note that this also occurs if you close an application, and happens when switching from an application to the scopes.

$ system-image-cli -i
current build number: 169
device name: mako
channel: ubuntu-touch/rc-proposed/bq-aquaris.en
last update: 2015-11-23 01:08:21
version version: 169
version ubuntu: 20151120.1
version device: 20150911
version custom: mako-1.1

Related branches

Launchpad Janitor (janitor) wrote :

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

Changed in unity8 (Ubuntu):
status: New → Confirmed
Michael Zanetti (mzanetti) wrote :

This is the relevant debug output while the stuttering occurs.

qtmir.surfaces: MirSurface["webbrowser-app"]::stopFrameDropper()
qtmir.applications: Application::setInternalState - appId= "webbrowser-app" state= SuspendingWaitProcess
qtmir.applications: TaskController::suspend - appId= "webbrowser-app"
qtmir.applications: Application::setInternalState - appId= "webbrowser-app" state= Suspended
qtmir.applications: ApplicationManager::onAppDataChanged: Received "state" update "webbrowser-app"

affects: unity8 (Ubuntu) → qtmir (Ubuntu)
Michał Sawicz (saviq) on 2015-11-23
Changed in qtmir (Ubuntu):
status: Confirmed → Triaged
importance: Undecided → High
Changed in canonical-devices-system-image:
assignee: nobody → Michał Sawicz (saviq)
importance: Undecided → High
status: New → Confirmed
milestone: none → backlog
Andrea Bernabei (faenil) wrote :

I'm currently seeing many-seconds delay on rc-proposed r308 on Krillin...

Not sure how I got there (yet) but when I switched from one app to others, it was freezing for a few seconds every time...pretty annoying :)

Andrea Bernabei (faenil) wrote :

In my case, I was continuously switching between Telegram and Twitter apps (post a tweet, then switch, chat a bit, then switch, etc)...could it have something to do with the browser? (since it's also part of the usecase presented by the bug author)

Andrew Hayzen (ahayzen) wrote :

Agreed, from playing about with this for a while now, anything that is using oxide (webbrowser or webapp) seems to cause a very large and noticeable delay. Although it should be confirmed that other apps are not susceptible to this.

Albert Astals Cid (aacid) wrote :

Cut the rope (which is also oxied based) is also a big reproducer of this bug when switching from it to somewhere else (in case you need help with reproducing)

Michał Sawicz (saviq) wrote :

<ted> So I think that the answer is, yeah, we do that syncronously.
 We do a dbus call to cgmanager to get the list of pids and try to write their proc value.
 If we fail, then we need a setuid helper for things like oxide.
 So it could be that spawning that helper is part of what is causing a delay
 I'm not sure how to do it another way though.
 We're not blocking on it running, the overhead is just starting it.

Changed in qtmir (Ubuntu):
status: Triaged → Opinion
tags: added: performance
Launchpad Janitor (janitor) wrote :

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

Changed in ubuntu-app-launch (Ubuntu):
status: New → Confirmed
Michał Sawicz (saviq) on 2016-11-11
Changed in ubuntu-app-launch (Ubuntu):
status: Confirmed → In Progress
Changed in qtmir (Ubuntu):
status: Opinion → Invalid
Changed in canonical-devices-system-image:
milestone: backlog → 14
status: Confirmed → In Progress
Changed in ubuntu-app-launch (Ubuntu):
assignee: nobody → Ted Gould (ted)
importance: Undecided → High
Daniel van Vugt (vanvugt) wrote :

Sounds like bug 1640443?

Pat McGowan (pat-mcgowan) wrote :

The silo works for me mx4 on proposed

Changed in canonical-devices-system-image:
status: In Progress → Fix Committed
Changed in canonical-devices-system-image:
status: Fix Committed → Fix Released
Ted Gould (ted) on 2017-02-04
Changed in ubuntu-app-launch (Ubuntu):
status: In Progress → Fix Released
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