RE: [squid-users] squid 2 redirects but does not cache from christophe.gravier@dont-contact.us on 2006-01-23 (squid-users)

From: <christophe.gravier@dont-contact.us>
Date: Mon, 23 Jan 2006 23:46:50 +0100 (CET)

>> -----Original Message-----
>> From: christophe.gravier@univ-st-etienne.fr
>> [mailto:christophe.gravier@univ-st-etienne.fr]
>> Sent: Monday, January 23, 2006 11:22 AM
>> To: Chris Robertson
>> Subject: RE: [squid-users] squid 2 redirects but does not cache
>> >> -----Original Message-----
>> >> From: Christophe Gravier
>> >> [mailto:christophe.gravier@univ-st-etienne.fr]
>> >> Sent: Sunday, January 22, 2006 5:26 AM
>> >> To: squid-users@squid-cache.org
>> >> Subject: [squid-users] squid 2 redirects but does not cache
>> >>
>> >>
>>
>> In fact, I wanted to run it as accelerator (with caching). In
>> squid.conf I
>> read:
>> # NOTE: enabling httpd_accel_host disables proxy-caching and #
>> ICP. If you want these features enabled also, set
>> # the 'httpd_accel_with_proxy' option.
>>
>> So that's what I tried.
>>
>
> So it's a definition problem. It is a bit ambiguous. Generally, an
> accelerator accepts requests from the internet and caches pages from a
> small number of servers that it is "responsible" for. A proxy accepts
> requests from the small number of clients it is "responsible" and
> caches pages from the internet. Having the option enabled shouldn't
> hurt anything, but I think it's unnecessary.
>

So "accelerator" means reverse proxy. (I known understand your
astonishment upon this part of the configuration !)

>>
>> Well, I am aware of cookies (it's embedded in my plone solution).
>> Regarding caching itself, I don't understand why under heavy load
>> (simulated with ab apache benchmark) they are really bad
>> performances and
>> meanwhile I see in store.log ONLY "RELEASE" operation.
>
> I would imagine that's fairly normal behavior for an accelerator. You
> should only see a CREATE action when a new object is encountered that
> can be cached, but isn't. S

Sorry, that's what I don't understand. (my fault ;)).
If it is responsible for one server for example, why, even upon
restarting, didn't I see any trace of CREATE for object cached (the object
the reverse proxy caches for "relieving" the servers ?)

> WAPOUT means that the object was in memory
> and was written to disk. SWAPIN is just the opposite. I think I
> remember reading that there is a problem with the 2.5 branch of Squid
> which prevents it from performing a SWAPIN (which isn't as big a
> problem as it sounds. Most operating systems cache file accesses to
> memory), but I might be mistaken. Watch the unfiltered access log.
> You should see some TCP_HITs and TCP_MEM_HITs. As for the poor
> performance, have you had a look at
> http://plone.org/documentation/tutorial/optimizing-plone/? The page at
> http://plone.org/documentation/tutorial/optimizing-plone/what-to-cache
> seems to have some hints at making plone play well with caches.
>

Ok I got it.

Regarding plone configuration, I just follow limi's recommandation. The
fact is in his example he received :Requests per second: 864.07 [#/sec]
(mean)
I do receive
Requests per second: 3 [#/sec] (mean)

Basically, "pure" plone without *any* cahcing policy is meant to response
to 0,7 request per sec.
Using wisely RamCache and HttpCache plone product raise it to 3 request
per sec. (it's so ok for a single use accessing the website to see it
being fast).
Now it needs scalability (reverse proxy) to be able to maintain service
under loads.
I do think squid will change this rate significantly. (in fact with or
without, i don't gain any digits).

Making tail -f on access.log,

As if it only tries to match against cache only for text/html and not
images etc. ...
>> In squid.conf it is
>> said:
>> TAG: cache_store_log
>> # Logs the activities of the storage manager. Shows which #
>> objects are ejected from the cache, and which objects are #
>> saved and for how long. To disable, enter "none". There are #
>> not really utilities to analyze this data, so you can safely #
>> disable it.
>>
>> So it is ok to see "RELEASE" operation but I never see "store" or
>> "caching" or whatever. How behave ours while accessing your pages ?
>> Thanks for your tips indeed (the extension is ok and the link
>> is really
>> great).
>> Regards,
>>
>
> I don't use the store log myself. Follow the access.log, as it shows
> the results of each request.
>
> Chris
Received on Mon Jan 23 2006 - 15:47:00 MST

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