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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 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 :). 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. 26.10.15 1:17, Eliezer Croitoru пишет: > Hey Yuri, > > 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. > Usually I am redirecting to this page: http://wiki.squid-cache.org/Features/StoreID/CollisionRisks#Several_real_world_examples > > 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. > 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. > Small thing from a nice day of mine: > 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. > 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. > 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. > > 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. > > 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. > > If you do want to understand more about the subject pick your favorite scripting language and just try to implement a simple object caching. > 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. > > While I do advise you to not use it I would hint you and others on another approach to the subject. > 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! > - You can alter\hack squid code to meet your needs > - You can write an ICAP service that will be able to alter the response headers so squid would think it is cachable by default. > - You can write an ECAP module that will be able to alter the response headers ... > - Write your own cache service with your algorithms in it. > > 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. > 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! > The reason that the content is not cachable is due to all these application that describe their content as not cachable! > 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. > 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). > > And I will try to write it in a geeky way: > deny_info 302:https://support.google.com/youtube/ big_system_that_doesnt_want_to_be_cached > > Eliezer > > * 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. > > > On 25/10/2015 17:17, Yuri Voinov wrote: >> > Hi gents, > > Pay attention to whether someone from the test SQUID 4 as extremely low > of cache hits from the new version? Particularly with respect to sites > HTTPS directive "no cache"? After replacing the Squid 3.4 to 4 squid > cache hit collapsed from 85 percent or more on the level of 5-15 > percent. I believe this is due to the exclusion of support guidelines > ignore-no-cache, which eliminates the possibility of aggressive caching > and reduces the value of caching proxy to almost zero. > > This HTTP caches normally. However, due to the widespread use of HTTPS > trends - caching dramatically decreased to unacceptable levels. > > Noticed there anyone else this effect? And what is now with caching? > >> >> >> _______________________________________________ >> squid-users mailing list >> squid-users@xxxxxxxxxxxxxxxxxxxxx >> http://lists.squid-cache.org/listinfo/squid-users >> > > _______________________________________________ > squid-users mailing list > squid-users@xxxxxxxxxxxxxxxxxxxxx > http://lists.squid-cache.org/listinfo/squid-users -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJWLS1vAAoJENNXIZxhPexGgtUH/RG6RwfaSitWYIWNf/ZyxLFQ D0+FCxd9U5l4xG7hCy/mN6UKl38nCWJAxqB16eo2OlvGrYrC1bUJSOdXwQj4cK64 vyu6HzNqN7PMywFIEclv1ie9rqivcepJftK2SJjlARZs1vRZeqzQJoH7NZCqKfPy Q6HHNtJ0MrtzqW9S0JYNrgWX0/PcMJT5eZQ1ShTSU1t99cubtJ6HpKF+OC/G+95N b8/TVdUfR1dZcvuLsaG2xqOKI2CCuD/Uk6z9QZzNujkhrTUM0Cn+2T77qf4+aeS4 endIfbcfQiCkMoV5kC0Vsb6HkazAvbPmmEm/WKHgUDRptGMHcwSQHQVXZ7AwDzk= =WXnQ -----END PGP SIGNATURE----- |
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