Re: libpq should not look up all host addresses at once

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От Noah Misch
Тема Re: libpq should not look up all host addresses at once
Дата
Msg-id 20180812062615.GA2619236@rfd.leadboat.com
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Ответ на Re: libpq should not look up all host addresses at once  (Tom Lane <tgl@sss.pgh.pa.us>)
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On Thu, Aug 09, 2018 at 02:32:58PM -0400, Tom Lane wrote:
> Chapman Flack <chap@anastigmatix.net> writes:
> > On 08/09/2018 11:05 AM, Tom Lane wrote:
> >> So I think what this code should do is (1) look up each hostname as it
> >> needs it, not all at once, and (2) proceed on to the next hostname
> >> if it gets a DNS lookup failure, not fail the whole connection attempt
> >> immediately.  As attached.
> 
> > Would it be worth the complexity to be a little async about it,
> > fling a few DNS requests out, and try the hosts in the order the
> > responses come back?
> 
> It would be nice if an async connection request didn't have to block during
> DNS lookups ... but I don't know of any portable library API for async DNS
> requests

https://c-ares.haxx.se/ is the async DNS API that I've experienced.  It works
well if you really need such a thing, but I haven't needed it in libpq.


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