Apache, Zope/Plone, cache question

Federico Guizzardi <c@xxxxxxxxx> · Wed, 28 Jan 2009 14:22:33 +0100

Hi All,
i have a question about Apache cache (mod_cache). My virtual host is the 
follow:

 <VirtualHost *:80>
  ServerName www.anexample.org
  UseCanonicalName On

  <IfModule mod_cache.c>
    CacheDefaultExpire 36000
    CacheEnable mem /
    CacheIgnoreCacheControl On
    CacheIgnoreNoLastMod On
    CacheMaxExpire 7200
    CacheStoreNoStore On
    <IfModule mod_mem_cache.c>
      MCacheSize 524288
      MCacheMaxObjectCount 100000
      MCacheMinObjectSize 1
      MCacheMaxObjectSize 200000
    </IfModule>
  </IfModule>
  <IfModule mod_proxy.c>
    <Proxy balancer://mycluster>
      BalancerMember http://127.0.0.1:8081 route=8081
      BalancerMember http://127.0.0.1:8082 route=8082
      BalancerMember http://127.0.0.1:8083 route=8083
    </Proxy>
    ProxyVia On
    ProxyPass / 
balancer://mycluster/VirtualHostBase/http/www.anexample.org:80/unjlc/VirtualHostRoot/
    ProxyPassReverse / 
balancer://mycluster/VirtualHostBase/http/www.anexaple.org:80/unjlc/VirtualHostRoot/
  </IfModule>
  CustomLog /var/log/apache2/access.log combined
  ErrorLog /var/log/apache2/error.log
</VirtualHost>

On ports 808x there are three zope servers. 

In this situation, i supposed that when a public page is called (at second 
time, obviously), only apache should works to answer to my request. Looking 
with tcpdump i found that the reality is different: in some cases, apache 
asks to zope the same page, before the page was expired. 
Is it a fault of my configuration or is it the natural way?

After that, i tested with two different browsers (firefox 3 and konqueror) 
asking the same page, and i found other thing that not match with my mind: 
when i ask the main page of the site with the second browser (thinking the 
page was in cache), apache asks to zope the page.
It seems cache works using a different cache for each client. Is it real?

For debug, i tried previous tests without the balancer and/or UseCanonicalName 
directives, but nothing changes. I looked apache log too and there's no 
error, and all needed modules are loaded correctly.

Thanks for attenction.
Cheers.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
dott. Federico Guizzardi
Reflab S.r.l.
Via della Pace n.1, 56021 Cascina (PI), Italy
phone  (+39) 050 754193
fax  (+39) 050 754707
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~