RE: Pre-fetching some URLs

From: LCDR Mark Purcell <>
Date: Fri, 25 Oct 1996 14:43:12 +0100

On Friday, 25 October, 1996 07:52, Claude Lecommandeur
[SMTP:Claude.Lecommandeur@Epfl.Ch] wrote:
> I had always thought that the commented lines in squid.conf were the
> actual default wired in squid. Looks like this is not true. It is very
> disturbing.

I guess this is the point I was trying to make, rather than suggesting that
the current defaults are wrong.

I realise this isn't shrink-wrapped software but a lot of people install it
out of the box and assume that the commented lines are defaults (squid.conf
states there is no default for ttl_pattern but further down it states there
is a default of 30 days and further down it states a default of 3 days).

I know I was confused and it would appear that others were/ are as well.
 It wasn't until I spent a couple of hours playing around with settings and
turning up the debug level that I understood what the values actually
meant. Ideally everyone would do this and the world would be a better
informed place.

The whole reason I starting looking into this was because I was constantly
getting documents being cached for up to three days (default for TAG http)
from sites which changed daily, it wasn't until I enabled ttl_pattern that
TTL was calculated based on the last modified date. This still doesn't
completely solve the problem because if any of your parents or neighbors
haven't enabled ttl_pattern (default config) then they will cache and
UDP_HIT (for 3 days by default) these stale documents.

Unfortunately a lot of big sites don't have the time to tune parameters and
have dumped software if it doesn't work 'reasonably' out of the box. (c.f. dumping squid because of a 1 second response time) While this
approach to software may or may not be 'reasonable' it is a factor of the
'real world' which we have to work with.

Enough philosophy. What about solutions?? I stand by my original
suggestion that ttl_pattern be enabled by default, the values are actually
irrelevant as long as they aren't too large. The three day default (listed
in squid.conf) seems reasonable:

ttl_pattern . 4320 20% 4320


Mark Purcell
Lieutenant Commander, RAN
+44 (1793) 783 739  (tel/fax)
Received on Fri Oct 25 1996 - 06:45:55 MDT

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