gnome-shell is taking more and more CPU over time, UI becomes slowly unusable

[James Mason]

I'm a relatively heavy desktop user, having multiple browsers running at any given time, lots of terminal windows, etc. However, my browsers don't use a lot of CPU as most of the tabs are suspended at any given moment.

On a regular basis, over time, my desktop becomes less and less usable. It starts with becoming noticeably slower, laggy, and eventually absolutely requiring a reboot since it becomes totally unusable.

At the same time my my system load is low, and remains low, while gnome-shell appears only to take more and more CPU. I often see it using 30, 50, 90, and sometimes 100% CPU, while the rest is idle.

It reaches the point where terminals don't easily

The only "fix" is rebooting, or restarting X.

I must admit that I've been seeing this on my laptop for years now, and there is no improvement in sight even though I upgrade Ubuntu to the next version every time an update is out.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: gnome-shell 3.36.2-1ubuntu1~20.04.1
ProcVersionSignature: Ubuntu 5.4.0-33.37-generic 5.4.34
Uname: Linux 5.4.0-33-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.3
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Thu Jun 18 11:53:00 2020
DisplayManager: gdm3
RelatedPackageVersions: mutter-common 3.36.2-1ubuntu1~20.04.1
SourcePackage: gnome-shell
UpgradeStatus: Upgraded to focal on 2020-04-28 (50 days ago)

[Daniel van Vugt (vanvugt)]

Thanks for the bug report.

The attachment 'ShellJournal.txt' seems to show this is a duplicate of bug 1880405. But also, we find most high CPU issues are caused by unsupported gnome-shell extensions and you have a few:

  '<email address hidden>',
  'TaskBar@zpydr',
  '<email address hidden>'

so please try disabling those via gnome-shell-extension-prefs.

[James Mason (jmason583)]

This seems to have been the case. So far so good. If it changes I'll act accordingly.

How about gnome-shell issuing an alert to the user that something nasty is happening in the background without them knowing about it?

[Daniel van Vugt (vanvugt)]

I guess you could make that argument for all programs -- why don't they monitor themselves for bugs, or at least for high CPU. The argument is stronger for something like gnome-shell that allows 3rd party extensions to introduce bugs.

If you would like to see such self-monitoring in future then please report it at:

  https://gitlab.gnome.org/GNOME/gnome-shell/-/issues

[James Mason (jmason583)]

Agreed, on both :)

I'll submit a suggestion there.

Thank you Daniel

[James Mason (jmason583)]

Daniel, how does one produce the shell journal log? I'm afraid the problem resurfaced even after I removed all the extensions.

[Daniel van Vugt (vanvugt)]

To get all of it:

  journalctl -b0 > journal.txt

Or to just watch for the latest messages:

  journalctl -f