SUMMARY When running on Wayland, plasmashell has a maximum number of windows that it can handle-- around 100. When more than this number is opened, plasmashell crashes. It can be restarted once the number of windows goes back down, but not while the number remains the same. (See the attached video.) STEPS TO REPRODUCE 1. Start a KDE Wayland session 2. Open 100 windows, then a few more OBSERVED RESULT plasmashell crashes. EXPECTED RESULT plasmashell continues to run. SOFTWARE/OS VERSIONS Windows: macOS: Linux/KDE Plasma: (available in About System) KDE Plasma Version: KDE Frameworks Version: Qt Version: ADDITIONAL INFORMATION This is happening on KDE Neon and Arch Linux (both currently with 6.0.4). The specific application does not matter. I recreated this in Neon with both Firefox and Kate, and most of my windows on Arch are typically Brave. The hardware also does not matter. I recreated this in Neon on VirtualBox, and in Arch on physical hardware (AMD CPU + NVIDIA GPU). When I'm teetering on the edge of the maximum window limit, opening the Notifications applet in the bottom panel is also able to count as a "window" and cause plasmashell to crash.
The video (~1 minute) is too large to attach. Here's a link instead: https://www.dropbox.com/scl/fi/ybenhbnf563428nr165gm/kde-plasma-100-windows.webm?rlkey=9hbuk02e2v89s0cvm5dbcex60&e=1&st=rtyscexo&dl=0
I can't seem to get gdb to give me any significant output for either plasmashell or kwin_wayland when this occurs (just threads exiting/starting, and output that shows up normally before the issue happens). Give that plasmashell's only output when the issue occurs is "The Wayland connection broke. Did the Wayland compositor die?", and that message doesn't come from plasmashell or kwin's codebase (I think it comes from Qt?), I'm not sure where to even start when it comes to debugging this.
*** This bug has been marked as a duplicate of bug 479492 ***