[ntp:hackers] Asynch resolver

Danny Mayer mayer at ntp.isc.org
Mon May 8 12:46:45 UTC 2006

Brian Utterback wrote:
> If it is not threaded, then how can it possibly be used to implement
> an async resolver? As you pointed out in your previous message, we
> cannot assume that the host name resolution is being done by DNS.
> Since library calls like getaddrinfo do not have a non-blocking
> interface, we cannot use them asynchronously unless they are used
> in either a separate thread or process.

BIND 8 uses it and it's very fast, supports extremely high volumes and
is single-threaded. Trust me, BIND 8 is able to do it in an asynchronous
fashion. Paul Vixie can chime in here with the gory details if you are
interested. Don't forget that ntpd is itself asynchronous, it doesn't
wait for responses to it's packets, it just moves on to the next item.
When it gets something back it processes it when it gets to it.


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