[dns-operations] good async DNS library

[John Levine]

In article <84CCFF1F-B98E-4E03-9767-2998AE82D072 at exonetric.com> you write:
>It might simpler to just fork a process of your existing code for every resolver request though.

If you're willing to use python, the regular dnspython library works
fine with the built in python3 concurrent.futures thread library.

I've done DNS queries in 100 threads in parallel on a not particularly
fast server with no trouble.  I could probably run more but that was
enough for my application.