On 29/05/17 05:21, Yuri wrote:
28.05.2017 21:09, Eduardo Carneiro пишет:
Ok. Tell me what technical details you need and I post here.
Configs. Logs. Topology. Usecases. Examples for single transactions.
But if this were an ignoring cache-control issue, wouldn't that happen on
squid 3.5.19 and previous versions as well?
With the same conf works on 3.5.19 but not in newest squid3 versions.
Once more. Ignoring cache-control in squid is deprecated due to RFC
requirements. So, it leads to drops down with byte HIT in general. I do
not remember when it exactly desupported in squid's code, but seems
approx. at some 3.5.x.
From 3.5.19 onwards ..
3.5.21 added support for Squid to differentiate between revalidation
checks that were always vs sometimes necessary. Fixing the situation
where responses had both a CC:private or CC:no-cache header and
information stating cacheability "freshness".
3.5.22 fixed issues that were then seen with missing Last-Modified and
old Date values, and the Collapsed Forwarding feature.
3.5.23 added support for caching objects with "Vary: *" which depended
on the change in .21, and caching of 3034 responses. Also fixed the main
outstanding issue behind Host verify MISS happening, and a regression in
the .22 collapsed forwarding change.
3.5.24 fixed a regression in the "cache deny" access control handling
which was causing some thing to be cached and revalidated when they
should not have. This may make some things now un-cacheable if there is
a misconfiguration in that directive.
3.5.25 fixed a stall that happens when SSL-Bump interacts with Host
verification through the SNI value. While not strictly related, having
it fixed allows a lot more Google/YouTube/Akamai transactions to reach
the caching stages so their operations start to be visible instead of
splice/tunnel'ed.
The expected effect of these changes was to fix several major
unnecessary bandwidth uses;
- cached YouTube videos starting mid-video when someone else using the
proxy had only partially watched the same video - causing the user to
force-refresh and purge the cached video.
- Chrome and similar Google originated downloads being a MISS for
identical objects.
- the often cited terrible HIT reduction on some major hosting
services (again Google, though also Akamai) traffic since 3.2 Host
verify was added.
- collapsed forwarding resulting in large objects being stored to the
cache then immediately deleted by a parallel fetch.
Amos
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