CPU usage spikes with pending messages

[Jeff Abrahamson]

When the screen lock (i3lock) is active and dunst queues a large number of messages, the CPU runs very hot. It is not unusual to hear the fan running on an otherwise quiescent machine and, on unlocking, to see the screen covered with dunst alerts (kind, though sometimes too many to read before they timeout) and the CPU load well above one, with top showing dunst chewing most of the CPU.

When the alerts dismiss, dunst drops its CPU usage to near zero and system load falls back to some reasonable quiescent level.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: dunst 1.4.1-1
ProcVersionSignature: Ubuntu 5.4.0-73.82-generic 5.4.106
Uname: Linux 5.4.0-73-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.17
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: i3
Date: Wed Jun 2 13:45:22 2021
EcryptfsInUse: Yes
InstallationDate: Installed on 2015-10-23 (2048 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
SourcePackage: dunst
UpgradeStatus: Upgraded to focal on 2020-06-04 (362 days ago)