gnome-shell uses 100% cpu when screen blanked

[Michael Gratton]

Recently I've noticed gnome-shell eating 100% of the CPU when the screen is blanked due to the session going idle.

This seems to have started happening sometime after upgrading to groovy back when it was still in beta.

ProblemType: Bug
DistroRelease: Ubuntu 20.10
Package: gnome-shell 3.38.1-1ubuntu1
ProcVersionSignature: Ubuntu 5.8.0-25.26-generic 5.8.14
Uname: Linux 5.8.0-25-generic x86_64
ApportVersion: 2.20.11-0ubuntu50.1
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: GNOME
Date: Thu Nov 19 17:04:37 2020
DisplayManager: gdm3
InstallationDate: Installed on 2018-08-13 (828 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
RebootRequiredPkgs:
 linux-image-5.8.0-26-generic
 linux-base
 linux-image-5.8.0-28-generic
 linux-base
RelatedPackageVersions: mutter-common 3.38.1-1ubuntu1
SourcePackage: gnome-shell
UpgradeStatus: Upgraded to groovy on 2020-09-24 (55 days ago)

[Daniel van Vugt (vanvugt)]

Thanks for the bug report. Your system log is certainly full of a lot of messages so it's easy to believe you might have high CPU too. But I can't tell what part of gnome-shell they came from.

Since so many bugs are caused by extensions, and nobody else is reporting this issue, the first thing we need to check is all:

'<email address hidden>', '<email address hidden>', '<email address hidden>', '<email address hidden>'

Please uninstall or just disable all of them in the Extensions app, then log out and log in again. Does the problem still occur? If so then it might be this:

https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/3098