Processes that are started through xfce4-session autostart are owned by init (pid 1) and continue running after logoff.
I have a wallpaper changer which changes background every 5 minutes. This does not get killed at logoff and a second instance is created at new login.
In Gnome these processes were owned by gnome-session and got automatically killed. But not so with Xfce, here they are owned by init and running forever.
How can I assure that such processes get killed at logoff?
Do a manual cleanup using a custom script called from ~/.config/xfce4/xinitrc Something along the lines of pkill -u $USER descriptivename