Is asychronous DNS lookup worth keeping at all?

Mark Atwood fallenpegasus at gmail.com
Tue Dec 1 16:12:42 UTC 2015


I'm inclined to say it's not worth it, and to rip it out, but I'm not yet
quite enough convinced of that to say do it.

Hal? Joel? Daniel? What do you think?

..m


On Tue, Dec 1, 2015 at 6:57 AM Eric S. Raymond <esr at snark.thyrsus.com>
wrote:

> Is asychronous DNS lookup worth keeping at all?  It's costly in code
> complexity and dependencies.  I've been thinking about how it affects
> performance and I'm now doubting that it is effective  in modern
> conditions.
>
> The basic fact here is that if you specify servers or pool hosts by
> DNS name, you can't get time corrections before the first DNS lookup
> succceeds.  Therefore, asynchronous getaddrinfo can improve time to first
> correction only if there is more than one host specified by name.
>
> Nowadays, 99.9% of all NTP installations are configured to do a single
> pool name lookup.  Some of the remainder are hand-configured by
> sysdamins who care about boot speed enough to specify IP addresses.
>
> The question is: does the remaining tiny fraction of installations
> justify the complexity cost?
> --
>                 <a href="http://www.catb.org/~esr/">Eric S. Raymond</a>
>
> "The great object is, that every man be armed. [...]
> Every one who is able may have a gun."
>         -- Patrick Henry, speech of June 14 1788
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