[squid-users] Only caching sometimes

Hi all,

Caching is not happening the way I expected.

I am using Squid to cache the 'expensive' output of a Zope server. Due to increased traffic on the site, I am getting many server errors (database conflict), so it is urgent that objects be cached. I instructed Zope to insert a Cache-Control header with 'max-age=7776000'. The object should be cached even if refreshment would result in changes.

All pages are made from the same script which I have tested with the Cacheability Engine. The response is, 'This object will be fresh for 12 weeks 6 days. The object had changed when validation was attempted'.

If I understand correctly from the log extracts below (access.log, store.log and Zope's Z2.log), the object has been dropped and re-entered into the cache. Why? How can I prevent this?

Thanks in advance!

Ken

--
202.202.202.202 - - [14/Jan/2004:01:47:45 +0100] "GET http://mysite.com:81/pathto/object_xyz HTTP/1.1" 500 2462 TCP_MISS:DIRECT
61.61.61.61 - - [14/Jan/2004:03:10:00 +0100] "GET http://mysite.com:81/pathto/object_xyz HTTP/1.0" 200 22366 TCP_MISS:DIRECT
64.64.64.64 - - [14/Jan/2004:03:15:06 +0100] "GET http://mysite.com:81/pathto/object_xyz HTTP/1.0" 200 22370 TCP_HIT:NONE
202.202.202.202 - - [14/Jan/2004:09:08:12 +0100] "GET http://mysite.com:81/pathto/object_xyz HTTP/1.1" 200 21699 TCP_MISS:DIRECT
206.168.0.6 - - [14/Jan/2004:09:27:07 +0100] "GET http://mysite.com:81/pathto/object_xyz HTTP/1.0" 200 21694 TCP_CLIENT_REFRESH_MISS:DIRECT
1074046198.938 RELEASE -1 FFFFFFFF C927B08545BF24772B34082FC7B5AC2A  500 1074041265        -1 1081817265 text/html 1865/1865 GET http://mysite.com:81/pathto/object_xyz
1074046199.623 SWAPOUT 00 00002075 C927B08545BF24772B34082FC7B5AC2A  200 1074046199        -1 1081822199 text/html 22053/22053 GET http://mysite.com:81/pathto/object_xyz
1074067689.816 SWAPOUT 00 00003591 C927B08545BF24772B34082FC7B5AC2A  200 1074067689        -1 1081843689 text/html 21386/21386 GET http://mysite.com:81/pathto/object_xyz
1074068826.935 SWAPOUT 00 00003662 C927B08545BF24772B34082FC7B5AC2A  200 1074068826        -1 1081844826 text/html 21386/21386 GET http://mysite.com:81/pathto/object_xyz
123.45.678.90 - Anonymous [14/Jan/2004:01:47:45 +0200] "GET /pathto/object_xyz HTTP/1.0" 200 2421 "" ""
123.45.678.90 - Anonymous [14/Jan/2004:03:09:59 +0200] "GET /pathto/object_xyz HTTP/1.0" 200 22325 "" ""
123.45.678.90 - Anonymous [14/Jan/2004:09:08:09 +0200] "GET /pathto/object_xyz HTTP/1.0" 200 21658 "" ""
123.45.678.90 - Anonymous [14/Jan/2004:09:27:06 +0200] "GET /pathto/object_xyz HTTP/1.0" 200 21658 "" "CacheabilityEngine/1.30 <http://www.mnot.net/cacheability/>"