Created attachment 182984 [details] lournal.log containing stack straces of threads after SIGQUIT SUMMARY Panels and widgets get unresponsive. Time display is frozen. Can't switch to applications by clicking on task panel. STEPS TO REPRODUCE 1. Most likely reproducible for me: Add a timer widget next to a clock widget on a panel. 2. Click and mouse move on both of them like crazy for a few seconds OBSERVED RESULT Time widget (seconds are displayed) frozen All panels and widgets unresponsive. All other applications not affected. EXPECTED RESULT No hang of plasmashell process. SOFTWARE/OS VERSIONS Operating System: Arch Linux KDE Plasma Version: 6.4.1 KDE Frameworks Version: 6.15.0 Qt Version: 6.9.1 Kernel Version: 6.15.4-arch2-1 (64-bit) Graphics Platform: Wayland Processors: 8 × AMD Ryzen 7 3700X 8-Core Processor Memory: 32 GiB of RAM (31.3 GiB usable) Graphics Processor: NVIDIA GeForce RTX 4060 Ti ADDITIONAL INFORMATION XDG_SESSION_TYPE=wayland XDG_CURRENT_DESKTOP=KDE WAYLAND_DISPLAY=wayland-0 Some static ENVs for forcing pure wayland and which avoided flickering in the past. Will test unsetting them. # Enable Wayland QT_QPA_PLATFORM="wayland;xcb" SDL_VIDEODRIVER="wayland,x11" GBM_BACKEND=nvidia-drm __GLX_VENDOR_LIBRARY_NAME=nvidia KWIN_TRIPLE_BUFFER=0 # Debugging QT_LOGGING_RULES="qt.qpa.*=true;qt.wayland.*=true" QT_DEBUG_PLUGINS=1 Does not help: KWIN_DRM_USE_MODIFIERS=0 QT_WAYLAND_DISABLE_WINDOWDECORATION=1 Workaround which helps: QT_QUICK_BACKEND=software I just know and understand threads in Python. Strace output of plasmashell process told me that the main thread suddenly does not realease a futex of a another thread. Full strace log attached. Just added some comments "^# " and renamed some thread numbers to "115775_Main, 115777_Hanger" for readability. Also attached a dumped stack trace of threads.
Created attachment 182985 [details] strace output of plasmashell session (zstd)
Just found another bunch of environment variables hiding in /etc/environment This old tweak coming from old and painful NVidia troubleshooting days got forgotten and causes the hangs on plasmashell: __GL_SYNC_TO_VBLANK=1 It's clearly reproducible with: $ __GL_SYNC_TO_VBLANK=1 plasmashell Still kind of a bug but doesn't affect many people probably? I'll close the topic for now. Thank you!
Thanks, good find!