RE: [users@httpd] Reverse Proxy Cache not Caching in 2.2.2

[Axel-Stéphane SMORGRAV <Ax...@europe.adp.com>]

> Anyway- looking at the log lines he sent later, perhaps this gives a clue:

Very clever. I can't believe I missed this. 

> Maybe this hostname is confusing mod_cache somehow.  The fact that it is caching the URL, but then doesn't serve from cache because nobody thinks they have it tells me it could be a weird naming issue.

The cache storage key is computed partly based on the return of ap_get_server_name which normally (unless UseCanonicalName DNS) will return either r->hostname or r->server->server_hostname (where r is the request_rec structure). Should the return value of ap_get_server_name be different at the time mod_cache determines whether there is an appropriate response, compared to the time at which the response is stored, the lookup would be made using a different key than the one under which the response would be stored, and hence the response would never be served from cache despite being stored in the cache.

Problem is that I have not found any good reason why the values of r->hostname or r->server->server_hostname should change during request processing. But I'll leave this excercise to someone who knows Apache internals well.

What I can suggest however, is to try to issue a request for the same URL using a browser that sets a Host header in the request (force HTTP 1.1 ??). The above warning is issued only when the request does not contain a host header. I tried to request http://media.rightmove.co.uk/14k/13115/13115_418671A_18671_IMG_00_t.JPG myself, but it appears to be served by "Server: Apache/1.3.29 (Unix)"

-ascs

-----Original Message-----
From: Nathan Seven [mailto:scosol@scosol.org] 
Sent: Wednesday, May 31, 2006 7:21 PM
To: users@httpd.apache.org
Subject: Re: [users@httpd] Reverse Proxy Cache not Caching in 2.2.2

Yes- my mind choked and read "2.2" instead of "2.2.2"-

Anyway- looking at the log lines he sent later, perhaps this gives a
clue:

 > [Tue May 30 11:29:34 2006] [warn] [client 10.6.3.3] proxy: no HTTP
0.9 request (with no host line) on incoming request and preserve host set forcing hostname to be media.rightmove.co.uk for uri /14k/ 13115/13115_418671A_18671_IMG_00_t.JPG

Maybe this hostname is confusing mod_cache somehow.  The fact that it is caching the URL, but then doesn't serve from cache because nobody thinks they have it tells me it could be a weird naming issue.

Anyway- there are other reasons that the response may not get cached, depending on the headers in the response and what you have things like CacheIgnoreCacheControl and CacheIgnoreNoLastMod etc-

http://httpd.apache.org/docs/2.2/mod/mod_cache.html

-SS

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