On my Dell XPS 9520/i7-12700H/32GB/RX 3050Ti system (but using the Intel iGPU) with a frequency of about once a week (of absolutely solid, almost 24/7 use) Plasma will freeze up whilst alt-tabbing between windows.
When this happened most recently (about 20 minutes ago) I had a metric ton of Firefox windows and tabs open, plus 5 Chrome windows with maybe 30 tabs (total) and about 5 Konsole windows (also with multiple tabs). Discover was open too. I.e. there was a lot of stress on the RAM and ZRAM (although that’s set to a healthy 31GB).
This has happened at least 3 times now, and only since I updated to KDE Plasma 5.27. I’m currently running 5.27.2 and X11. I’m running X11 because I was having problems with power settings in Wayland not being honored: that’s apparently now been fixed. Because I - voluntarily - reboot infrequently I haven’t switched back to Wayland (to test the fix and just use Wayland generally) so I don’t know if this has an X11-specific component.
The odd thing is that even though Plasma is frozen solid - looks like a deadlock somewhere to me - the machine is still alive. So I log into a TTY session via ctrl-alt-F3 and kill off startplasma-x11. Then I get bounced into SDDM and can log back in. The previous session is gone of course but pretty much everything is recoverable (thankfully I wasn’t editing when any of this happened, although emacs would have likely saved my bacon, give or take).
Has anyone else experienced this behavior? I did a search of course but didn’t find anything recent that sounded similar. I have a sneaking suspicion that it could be related to this laptop, specifically its high-performance processor (since if it is a deadlock it’s undoubtedly due to an IPC/thread synchronization issue).
Presumably, if I attach gdb to the startplasma-x11 process, and have symbols, I might discover if there is an actual deadlock, or at least that all threads are waiting on various IPC mechanisms?