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RE: Multi handle DNS cache entry expiration

From: Vladimir Grishchenko <vladgri_at_hotmail.com>
Date: Mon, 1 Apr 2013 10:46:25 -0700

> > With one multi and 4 easy handles at max often it takes more than 60 seconds
> > between gethostbyname calls. Using 7.23.1 and sync resolver.
>
> Then perhaps you should consider upping the timeout?
>
> CURLOPT_DNS_CACHE_TIMEOUT is a bit funny as it is still set per easy handle
> even when you use the multi handle, which could perhaps be a reason for change
> at some point...
>
> --
>
> / daniel.haxx.se

I'm not fully clear about your suggestion about upping the timeout. Currently our app only talks to one host only so yes, generally upping the timeout would be a sensible thing to do. However I would expect to see a gethostbyname call every 60 seconds by default but it sometimes takes longer when requests are going out back to back.

Can this have something to do with cached connections, as if there is a match for a given hostname/port and the connection is considering to be good no name lookup is attempted despite the fact the corresponding DNS cache entry is technically stale per configured CURLOPT_DNS_CACHE_TIMEOUT value?
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Received on 2013-04-01