Re: [squid-users] Strange misses of cacheable objects

On 15/04/2014 1:07 a.m., Anatoli wrote:
> Dear all,
>
> I have some strange misses of cacheable objects. Here is an example (there
> are a lot of these objects):
>
> http://www.googletagmanager.com/gtm.js?id=GTM-J5TM
>

As Michael said this one is expired immediately on arrival.
 Note: in HTTP/1.1 expired responses ARE cacheable without any special
actions.

It is also private data for the individual client. Squid is now
enforcing revalidation of private responses which make their way into
the cache. That ensures the new requestor is a valid recipient of any
cached response.

> Some other links with very similar request/response headers and squid log
> entries are
> http://www.googleadservices.com/pagead/conversion_async.js

Same for this one in regards to immediate expiry. However the ETag
header contains invalid values so HTTP/1.1 revalidation does not work.

> http://cdn.clicktale.net/www07/ptc/3a4e2875-764c-4dd7-8d30-db51f1744e3e.js
> http://cdn.clicktale.net/www/tc/WRe10.js

These URL are emitting a mix of different Vary: header contents. Which
make caching highly volatile and likely to produce incorrect responses
to clients.

 The ETag header used for unique object identification on the second one
is also containing invalid values (this time duplicates) in some responses.

Both of these server errors will cause erratic behaviour in the caching
of the objects as they undermine the reliability of the response.

>
> http://armdl.adobe.com/pub/adobe/reader/win/9.x/9.5.0/en_US/AdbeRdr950_en_US
> .exe has the same behavior and was already reported by Marko Cupać @ May 15,
> 2013; 7:17am in "adobe updates constantly re-downloading" mail. Nobody
> offered any solution.

Since Marko's original post I have seen simialr behaviour on a different
clients network when the user account logged into the machine did not
have permission to install software yet Adobe updater was running anyway
and failing at the beginning install stage.

Amos
Received on Mon Apr 14 2014 - 15:19:28 MDT