Hello Paul, I am not involved in packaging kicad or wxwidgets, just trying to collect some more information.
Could you recheck - could it be that this pid 309563 was still running from a previous kicad session and your hanging kicad was another, newer process? Because, I guess, the __run_exit_handlers should just run at process exit. The last line in your backtrace point to this line, with a loop which would fit into the picture: https://sources.debian.org/src/wxwidgets3.0/3.0.4+dfsg-15/src/common/object.cpp/#L177 When you are in gdb and try to leave the current function by "finish", do you get again to the debugger prompt, or is it causing already the 100% CPU usage again? Kind regards, Bernhard