I looked up and have those as well and many more but those are associated with app name.(like Skype, Mail and others)
One way to find more is to use console and type xpcd in search.
I did that and it found some apps without correct permission.
So the suggestion is to restore the permissions that might stop the xpcd events.
I also found a good answer and explanation here.
That isn't actually launchctl creating a new process; it's most likely
dnsmasq (or other apps) itself. If it fork()s into the background, launchd can't tell;
then when it talks to launchd, launchd creates an anonymous entry for
it. Make sure example dnsmasq doesn't background itself.
(The - listed for the regular launchctl list output indicates that the
original dnsmasq process exited.)