[squid-users] Getting the full file content on a range request, but not on EVERY get ...

[Alex Rousskov]

On 05/12/2016 02:36 PM, Amos Jeffries wrote:

> Have you given collapsed_forwarding a try? Its supposed to prevent all
> the duplicate requests making all those extra upstream connections unti
> at least the first one has finished getting the object.

For the record, collapsed forwarding collapses requests _before_ there
is any response [header], not after the "first" request got the object
[body]. Once there is a response [header], the usual caching code path
kicks in and no collapsing is needed.

Cache hits on that "usual caching code path" read from a "public" cache
entry. Normally, those public entries are created when Squid receives a
response [header]. Collapsed forwarding creates that entry before Squids
gets the response [header], and, hence, before Squid can know for sure
whether the response is going to be cachable, with all the risks that
entails.


Please do not misinterpret my email as a recommendation to give (or not
to give) collapsed forwarding a try. I have _not_ analyzed the problems
discussed on this thread. I just wanted to correct the description
above. Nothing more.


HTH,

Alex.