Re: [squid-users] Request processing question

From: Henrik Nordstrom <>
Date: Sun, 06 Apr 2008 10:59:48 +0200

lör 2008-04-05 klockan 23:26 -0400 skrev David Lawson:
> I've got a couple questions about how Squid chooses to fulfill a
> request. Basically, I've got a cache with a number of sibling peers
> defined. Some of the time it makes an ICP query to those peers and
> then does everything it should do, takes the first hit, makes the HTTP
> request for the object via that peer, etc. Some, perhaps most, of the
> time, it doesn't even make an ICP query for the object, it just goes
> direct to the origin server.

The primary distinction is hierarchical/nonhierarchical requests.
Siblings is only queried on hierarchical requests.

  - reload requests
  - cache validations if you have non-Squid ICP peers
  - non-GET/HEAD/TRACE requests
  - authenticated requests
  - matching hierarchy_stoplist

> I've also got a broader, more general question of how a request flows
> through the Squid process, when ACLs are processed, are they before or
> after any rewriter is done to the URLs, etc., but that's a really
> secondary thing, right now I'm just concerned with the ICP question.

Depends on which access directive you look at. Generally speaking
http_access is before url rewrites, the rest after.

Received on Sun Apr 06 2008 - 03:01:15 MDT

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