Re: Re: mod_mem_cache on a proxy server

[Frederic Paillart <Frederic.PAILLART@xxxxxxxxxxx>]

Hi Francois,

I've already sent a POST regarding the mod_mem_cache usage.
http://httpd.markmail.org/search/?q=paillart#query:paillart+page:1+mid:bws5recajzhtqc7k+state:results

>From my point of view, this module is not really usable.
I've benchmarked the mod_disk_cache module and found same results as for mod_mem_cache in my use case (download iso files).
So the best way is to use this cache implementation.
Thanks to the sendfile mechanism !!!

Regarding your problem :

1. You have to configure your cache to not store the Set-Cookie Header :
CacheIgnoreHeaders Set-Cookie

2. Because your clients don't send conditional Headers, it will receive always the whole content.
In such case, the cache will be efficient only between apache and mongrel.

3. You set both the Expires and Cache-Control:max-age headers. According to the HTTP/1.1 specifications :

"The max-age directive takes priority over Expires, so if max-age is present in a response, the calculation is simply:
freshness_lifetime = max_age_value"

So only the Cache-Control:max-age header (300) will be taken into account.
Unfortunately you have also set a Last-Modified header to "Thu Apr 03 11:19:22 UTC 2008".

According to the HTTP/1.1 specifications :

"Also, if the response does have a Last-Modified time, the heuristic expiration value SHOULD be no more than some fraction of the interval since that time. A typical setting of this fraction might be 10%.
The calculation to determine if a response has expired is quite simple:

      response_is_fresh = (freshness_lifetime > current_age)"

From my point of view, your content is already deprecated, so it will not be cached.
To verify these hypotheses, you can send me your apache error_log by enabling the DumpIO  :
DumpIOInput On
DumpIOOutput On
LogLevel debug

Bye

Fred


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title:Development Engineer
tel;work:04 42 36 43 38
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