AMuse:
Hey all, I wanted to chime in on this thread because I'm suddenly seeing DNS "Overload" errors (and corresponding notices that my system is overloaded on prometheus) lately as well.
The hardware and OS and configs for my public exit haven't changed - what has changed is that I upgraded tor itself, and added ipv6.
You appear to be running tor 0.4.6.8 on FreeBSD.
As has been previously stated on this thread the code involved has been changed in tor 0.4.6.9 and 0.4.7.3-alpha.
So you will have to wait till FreeBSD ports ship that version.
https://www.freshports.org/security/tor/
After upgrading the tor version the overload indicator on will disappear when it it was DNS related (there can be other reasons).
kind regards, nusenu