Re: [squid-users] Re: Advantages of squid?

Eric B. wrote:
> "Amos Jeffries" <squid3_at_treenet.co.nz> wrote in message
> news:499751AD.5030706_at_treenet.co.nz...
>> Eric B. wrote:
>
>> I've found a noticable speed increase (50%) in all sites when I placed a
>> squid box in front of the web servers. But your experience may vary.
>
> Wow - that's amazing. I guess I'm a little confused as to how / why squid
> is so much more effective at serving static content than apache would be for
> instance. Given the same static image or the same static html, what makes
> squid so much better / faster?

In my case it was dramatic because the apache was slowed down serving
other sites as well as proxying for tomcat.

>
>>> I guess I can see squid would end up offloading some of the processing
>>> from tomcat, but if I were to put them on the same server, then it ends
>>> up being the same CPU/disk that get used, so I don't see any advantages
>>> there either - the processing power just gets shifted from one app to
>>> another.
>> Tomcat will attempting to re-generate content it does not have to, simply
>> because it has a dynamic type or because its not storing the response
>> headers. Squid will fix this minor CPU waste.
>> As I said though if they are on different boxes, that is when savings are
>> maximized.
>
> How does squid know what is static and can be cached, and what is dynamic?

As far as squid is concerned its all 'static' (dynamic stuff is
pre-created by tomcat by the time it reaches squid).
The HTTP headers tell squid how long things can be cached for, or not in
some cases.

> Is that based on configuration of file extensions? ie: cache html pages,
> jpg and gif, but not php and jsp? Furthermore, if a request is made with
> the same uri & query string, will squid cache the result?

If the headers permit yes.

Query strings, may need a little adjustment to the configuration on
older squid:
http://wiki.squid-cache.org/ConfigExamples/DynamicContent

Amos

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