Bug 436796

SUMMARY

Clock plasmoids (including Digital Clock and its forks) would skip or briefly display the first second of each minute (e.g. 12:34:00). In rare cases, clock plasmoids would randomly skip/briefly display other seconds as well.

STEPS TO REPRODUCE
1. Add any clock plasmoid that supports displaying seconds to the desktop or any panel, if there isn't one
2. Configure the plasmoid to show seconds (in the case of Digital Clock, right click the plasmoid, click "Configure Digital Clock", check "Show seconds" under the Appearance tab, and apply changes)
3. Observe that the clock updates irregularly when the minute increments (e.g. 12:00:59 -> 12:01:00)

OBSERVED RESULT

Within the last few seconds of any minute, the clock would slow down (i.e. one of the seconds would not update for more than 1 second). When the minute changes, the next second (e.g. 12:01:00) is shown for about half a second or not at all.

EXPECTED RESULT

The clock would consistently display each second in uniformly spaced intervals.

SOFTWARE/OS VERSIONS
Linux: Kernel 5.11 on Manjaro (I also have kernel versions 5.10 LTS and 5.4 LTS as fallbacks)
KDE Plasma Version: 5.21.4
KDE Frameworks Version: 5.81.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION

This behavior can be inconsistent, at least in recent Plasma releases, as clock plasmoids would sometimes display the first second of each minute properly. I can also work around this by restarting plasmashell over and over until the irregular updates stop, but after a while, the irregular updates return in the same plasmashell instance.

This behavior affects ALL clock plasmoids (built-in Analog Clock, Zren's Event Calendar, etc.) but is most noticable with a digital clock. This behavior also occurs when the plasmoid is loaded into Latte Dock, which I no longer use as of submitting this ticket.

I believe this is likely related to Bug #392476 since that ticket also deals with clock updates.

My Linux kernel version and distro are likely irrelevant, but they may still be helpful. This bug has persisted since I started using Plasma daily on the same machine with version 5.16. Additionally, I first spotted this behavior when I first tried Plasma on a Linux machine running Fedora 24 back in 2016!

I am frustrated that this annoyance has not been fixed in the past 5 years or so, and that I've never seen this oddity happen in other desktop environments (including Windows and macOS).