Re: [squid-users] I want to verify why squid wont cache a specific object.

From: Amos Jeffries <>
Date: Mon, 20 Aug 2012 13:03:48 +1200

On 20.08.2012 12:22, Eliezer Croitoru wrote:
> On 8/20/2012 2:37 AM, Eliezer Croitoru wrote:
>> On 8/20/2012 1:38 AM, Amos Jeffries wrote:
>>> The FFFFFFFF is the file number/name where it is being stored.
>>> Since
>>> this is an erased operation that is always the magic F value.
>>> It is not 1-to-1 related to the object being cacheable. It just
>>> means
>>> the object *currently* stored needs removing. Non-cacheable objects
>>> the
>>> RELEASE immediately follows storage, for cacheable objects being
>>> replaced the erase of old content immediately follows storage of
>>> new
>>> copies.
>> OK
> <SNIP>
> just a bit more interesting data.
> there is a different between intercepted requests(NAT and TPROXTY)
> to using regular proxy http requests.
> on regular proxy everything works fine and the file is being cached
> always.
> (I use two squids.. both with url rewriter that causes the like
> "store_url_rewite" effect on the cache.)
> it works always for youtube on the same setup so I dont really know
> what the cause can be.
> it narrows down the bug into a very small area which is:
> 3.2.1 TPROXY\INTERCEPT + cache_peer + specific requests
> vs
> 3.2.1 regular proxy + cache_peer + specific requests

Ah. The Host verification may be affecting things there. If that fails
the requested URL is marked non-cacheable (for the intercepting proxy).
We don't yet have a good separation on the storage systems to make
non-cacheables leave cached content alone. So this is likely to result
in cached content being invalidated.

IIRC you were having trouble with verification preventing relay to
peers. Which is a strong indication that the no-store flag will have
been set by that destination trust check.

> there is a different in the requests that was made on regular proxy
> or intercepted requests that the url has a "@" sign in it but it's
> not
> suppose to change a thing.
> I will file a bug later but I want first to verify more about it.

If you wish. It is a minor regression for the use-cases where traffic
is being fetched from sources other than ORIGINAL_DST. That content
should still be cacheable as it was before. It is done this way for now
so that swapping ORIGINAL_DST in for DIRECT at selection time will be
safe, and that selection point is far too late to create cache entries
when it turns out to be safely cacheable despite the verify failing.

However, I noted that your system is a two-layer proxy and both layers
are MISS'ing. For the Host verification possibility only the gateway
intercepting cache would be forced to MISS by those flags. The second
layer is completely unaware of the intercept or Host error and treats it
as normal forward-proxy traffic, caching and all. I would expect this
situation to appear as MISS on your frontend proxy and HIT on your
backend proxy before reaching the cloud proxy.

Received on Mon Aug 20 2012 - 01:03:53 MDT

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