I have issue with wallpaper. When I am switching desktop, wallpaper is not moving along but "stays under".
killall Dock fixes this but recently it is occurring so often that it became annoying.
What could be issue? Is there permanent solution?
It's not obvious to me why the
killall Dock command would help with this, but since it does it may be worth you doing a reset and restart of the Dock.
Reset and restart the Dock
If you go ahead with resetting and restarting the Dock you will need to re-add any non-default icons to your Dock. (I usually find it's a good opportunity for people to start afresh and only add things as they actually use them).
To reset and restart the Dock follow these steps:
killall -KILL Dock
Remember you'll need to re-add some apps back to the Dock.
If this doesn't resolve your issue, it'd be worth also testing what happens when you're booted into Safe Mode and afterwards again. See below.
Boot into Safe Mode
Follow these steps to boot your Mac into Safe Mode:
Once you've booted into Safe Mode, let me know how you went.
It took me some time to resolve it but I noticed relation between my issue and this BUG appearing in system.log:
Jun 20 09:32:48 myhost Dock: BUG in libdispatch client: kevent[EVFILT_MACHPORT] monitored resource vanished before the source cancel handler was invoked
Moreover I noticed connection between bug occurrences and my tasks performed. Bug was appearing only when I was using Sublime Text 3. I changed it for another code editor and since then I did not have this issue.