Re: Squid 2.0 PATCH2 no-query peers and HUP.

From: John Sloan <>
Date: Tue, 20 Oct 1998 14:36:51 +0100 (BST)

On Tue, 20 Oct 1998, Niall Doherty wrote:

> Hi John,
> > I've set my caches to peer with each other no-query, since they all have
> > cache-digests enabled, and yet they still were sending ICP to each other
> > (I would have thought that this was unncessesary?).
> The default is to send ICP queries. If you want HTCP you specify "htcp"
> as an option and the port number (probably 4827 instead of 3130).
> Maybe the default should be to have no "querying" method unless explicitly
> specified, but this would mean changing the syntax of the config file quite
> a bit I think.

The default seems to be to send ICP queries _and_ request cache digests.
This seems redundant, and negates part of the point of using cache digests
(the savings on inter-cache traffic). I would have though a peer request
algorithm which checked for cache_digest, and fell back to ICP query if
that didn't exist would have been more useful. It would ameliorate the
startup problem I discovered as well.
> > Anyway I made this change and HUPed them in fairly quick succession, and
> > managed to get the following error appearing in the cache_log:
> >
> > 1998/10/20 12:55:13| internalStart: unknown request:
> > GET /squid-internal-periodic/store_digest HTTP/1.0
> >
> > So far it appears that only one cache is getting CACHE_DIGEST_HITs from
> > one of the others. I guess because the other initial cache_digest
> > requests all failed in this manner.
> This is most likely a sibling asking you for your cache digest, which
> you haven't got built internally yet. It'll get built sooner or later
> (look at the Event Queue in the cache manager to see when it's due next)
> and then those messages will disappear.

I only got them the once. And indeed as I expected some time later all
caches are succesfully getting cache digest hits from each other. However
the failure mode when the cache_digest hasn't yet been built is a little
graceless. That was the nature of my comment, more than anything else.

> Niall


John Sloan
UK Unix Systems Administrator
UUNET Worldcom
Received on Tue Oct 20 1998 - 07:52:15 MDT

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