Re: [squid-users] Accelerating proxy not matching cgi files

From: Amos Jeffries <>
Date: Thu, 25 Aug 2011 02:02:01 +1200

On 24/08/11 06:51, Mateusz Buc wrote:
> 2011/8/23 Amos Jeffries:
>> You have an internal part of your site performing GET requests?
>> Or did you mean it generates an index page containing a set of volatile URLs
>> for IMG or A tags?
> Sorry, it was misunderstanding. index.cgi contains set of volatile
> URLs, such as the gen.cgi link example I provided earlier.


>> Ouch. Bad, bad, bad for caching. Caches only works when the URLs are stable
>> with repeated calls to the same ones.
> I forgot to mention that gen.cgi URLs only change, when the log data
> changes, so sometimes it could be once for a 15 minutes I suppose. It

I kind of assumed that was the case. All my previous suggestions still
apply unchanged.
  This extra info only means that you can probably succeed with simple
the ETag calculations. Which leads to some rather nice effects.

> all depends on the information index.cgi gets from data-gathering
> software. It changes timestamps or other info in URL only when log
> data changes.

That is where I have a big conceptual problem:
  gen.cgi is accessing and using the data. Yet does not have any way to
identify when it last changed?
  If you can make gen.cgi have that info index.cgi knowledge becomes

> Today I made an expirement and analyzed apache server
> logs. It turned out that about 40% of all gen.cgi links were repeated
> at least once - it means that they were downloaded at least twice. So
> I guess they should be cached at least for a while, shouldn't they?

Maybe. We would need to see the HTTP headers produced by gen.cgi to be
sure. From the description of how index.cgi/gen.cgi interact I think it
highly likely the lack of Cache-Control and Last-Modified information
from gen.cgi is causing the cache algorithms to determine its unsafe to


Please be using
   Current Stable Squid 2.7.STABLE9 or 3.1.14
   Beta testers wanted for
Received on Wed Aug 24 2011 - 14:03:23 MDT

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