Date: Sun, 02 Oct 2011 11:10:24 +0100 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: Doug Barton <dougb@freebsd.org> Cc: freebsd-stable@freebsd.org, Jeremy Chadwick <freebsd@jdc.parodius.com> Subject: Re: 7.3 + kqueue + apache/php + DNS lookup problem Message-ID: <4E883890.4020704@infracaninophile.co.uk> In-Reply-To: <4E866A70.8060203@FreeBSD.org> References: <4E865146.8090108@FreeBSD.org> <20111001003735.GA28346@icarus.home.lan> <4E866A70.8060203@FreeBSD.org>
next in thread | previous in thread | raw e-mail | index | archive | help
This is an OpenPGP/MIME signed message (RFC 2440 and 3156)
--------------enig53E550BC93E0603B67CCCE20
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
On 01/10/2011 02:18, Doug Barton wrote:
>> Does this happen when httpd tries to do DNS resolution for, say, an
>> > incoming connection to the web server (e.g. trying to resolve the
>> > incoming IP address of the client to an FQDN), or is it happening wi=
thin
>> > some PHP code (assuming PHP is installed/used as an Apache module)
>> > that's trying to do DNS resolution of some kind?
> It's a php module doing a lookup for the hostname of the back-end mysql=
> server.
Hmmm... Is this a function of DNS traffic being via UDP? Presumably
you're not seeing the same sort of delays when eg. apache connects to
mysql via TCP.
Hard to think of another UDP protocol you could use to test -- SNMP
perhaps? Or somehow forcing the DNS traffic to go via TCP? Tricky to
make that happen when the resolver is on localhost. Of course, since
DNS will only fall back to TCP after trying UDP, that's going to be even
slower overall than your current situation, but the point here is to
examine the truss output for timing details specifically around where
the TCP query is issued.
Cheers,
Matthew
--=20
Dr Matthew J Seaman MA, D.Phil. 7 Priory Courtyard
Flat 3
PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate
JID: matthew@infracaninophile.co.uk Kent, CT11 9PW
--------------enig53E550BC93E0603B67CCCE20
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: OpenPGP digital signature
Content-Disposition: attachment; filename="signature.asc"
-----BEGIN PGP SIGNATURE-----
Version: GnuPG/MacGPG2 v2.0.16 (Darwin)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/
iEYEARECAAYFAk6IOJcACgkQ8Mjk52CukIwKWQCfUPe85Qs07MkU2GC4zfRkrTFv
za4An0tWh7LsUuxdfbfVU40SLbEyo4ZM
=71kT
-----END PGP SIGNATURE-----
--------------enig53E550BC93E0603B67CCCE20--
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4E883890.4020704>