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Actually, I'm experienced enough not to need retelling truths. I'm
aware of, and how difficult it is to cache dynamic content, and it's
exactly what I wrote Vicki why it is impossible to cache YouTube :).<br>
<br>
It's not about that. It's about the fact that, with exactly the same
parameters caching and maintaining the cache at the same URL, which
I used to get 85% cache hit, I am now, with a SQUID 4, I get 0%.
That's all.<br>
<br>
26.10.15 1:17, Eliezer Croitoru пишет:<br>
<span style="white-space: pre;">> Hey Yuri,<br>
><br>
> I am not sure if you think that Squid version 4 with extreme
low hit ratio is bad or not but I can understand your sight about
things.<br>
> Usually I am redirecting to this page:
<a class="moz-txt-link-freetext" href="http://wiki.squid-cache.org/Features/StoreID/CollisionRisks#Several_real_world_examples">http://wiki.squid-cache.org/Features/StoreID/CollisionRisks#Several_real_world_examples</a><br>
><br>
> But this time I can proudly say that the squid project is
doing things the right way while it might not be understood by
some.<br>
> Before you or anyone declares that there is a low hit ratio
due to something that is missing I will try to put some sense into
how things looks in the real world.<br>
> Small thing from a nice day of mine:<br>
> I was sitting talking with a friend of mine, a MD to be exact
and while we were talking I was just comforting him about the
wonders of Computers.<br>
> He was complaining on how the software in the office moves so
slow and he needs to wait for the software to response with
results. So I hesitated a bit but then I asked him "What would
have happen if some MD here in the office will receive the wrong
content\results on a patient from the software? he described it to
me terrified from the question 'He can get the wrong decision!'
and then I described to him how he is in such a good place when he
doesn't need to fear from such scenarios.<br>
> In this same office Squid is being used for many things and
it's crucial that besides the option to cache content the
possibility to validate cache properly will be set right.<br>
><br>
> I do understand that there is a need for caches and sometimes
it is crucial in order to give the application more CPU cycles or
more RAM but sometimes the hunger for cache can consume the actual
requirement for the content integrity and it must be re-validated
from time to time.<br>
><br>
> I have seen couple times how a cache in a DB or other levels
results with a very bad and unwanted result while I do understand
some of the complexity and caution that the programmers take when
building all sort of systems with cache in them.<br>
><br>
> If you do want to understand more about the subject pick your
favorite scripting language and just try to implement a simple
object caching.<br>
> You would then see how complex the task can be and you can
maybe then understand why caches are not such a simple thing and
specially why ignore-no-cache should not be used in any
environment if it is possible.<br>
><br>
> While I do advise you to not use it I would hint you and
others on another approach to the subject.<br>
> If you are greedy and you have hunger for cache for specific
sites\traffic and you would like to be able to benefit from
over-caching there is a solution for that!<br>
> - You can alter\hack squid code to meet your needs<br>
> - You can write an ICAP service that will be able to alter
the response headers so squid would think it is cachable by
default.<br>
> - You can write an ECAP module that will be able to alter the
response headers ...<br>
> - Write your own cache service with your algorithms in it.<br>
><br>
> Take in account that the squid project tries to be as fault
tolerance as possible due to it being a very sensitive piece of
software in very big production systems.<br>
> Squid doesn't try to meet the requirement of "Maximum Cache"
and it is not squid that as a caching proxy makes a reduction of
any cache percentage!<br>
> The reason that the content is not cachable is due to all
these application that describe their content as not cachable!<br>
> For a second of sanity from the the squid project, try to
contact google\youtube admins\support\operators\forces\what-ever
to understand how would you be able to benefit from a local cache.<br>
> If and when you do manage to contact them let them know I was
looking for a contact and I never managed to find one of these
available to me on the phone or email. You cannot say anything
like that on the squid project, the squid project can be contacted
using an email and if required you can get a hold of the man
behind the software(while he is a human).<br>
><br>
> And I will try to write it in a geeky way:<br>
> deny_info 302:<a class="moz-txt-link-freetext" href="https://support.google.com/youtube/">https://support.google.com/youtube/</a>
big_system_that_doesnt_want_to_be_cached<br>
><br>
> Eliezer<br>
><br>
> * P.S If you do want to write an ICAP service or an ECAP
module to replace the "ignore-no-cache" I can give you some code
that will might help you as a starter.<br>
><br>
><br>
> On 25/10/2015 17:17, Yuri Voinov wrote:<br>
>><br>
> Hi gents,<br>
><br>
> Pay attention to whether someone from the test SQUID 4 as
extremely low<br>
> of cache hits from the new version? Particularly with respect
to sites<br>
> HTTPS directive "no cache"? After replacing the Squid 3.4 to
4 squid<br>
> cache hit collapsed from 85 percent or more on the level of
5-15<br>
> percent. I believe this is due to the exclusion of support
guidelines<br>
> ignore-no-cache, which eliminates the possibility of
aggressive caching<br>
> and reduces the value of caching proxy to almost zero.<br>
><br>
> This HTTP caches normally. However, due to the widespread use
of HTTPS<br>
> trends - caching dramatically decreased to unacceptable
levels.<br>
><br>
> Noticed there anyone else this effect? And what is now with
caching?<br>
><br>
>><br>
>><br>
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>><br>
><br>
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