Unconditional GETs and 304 from backend servers

Daniel Rodriguez coolbomb at gmail.com
Thu Jan 7 16:42:29 CET 2010


Thank you for your reply. I have been talking to our developers and
your proposed solution would take too much time and effort, but
anyways we have assigned someone to study the implications and how to
achieve that.

In another line, I see that in the varnish shopping list there is a:

"11. Backend revalidation

Support using conditional GETs to revalidate objects with the backend.
(vcl option)"

We may be interested to sponsor/pay the development of this feature. I
don't know how this may be handled and in what conditions but its
something that the company where I work could do to help the project.

Best Regards,

On Mon, Jan 4, 2010 at 10:48 AM, Tollef Fog Heen
<tfheen at redpill-linpro.com> wrote:
> ]] Daniel Rodriguez
> | The problem that we are currently having is that varnish will only ask
> | unconditional GETs, so every time that varnish ask the web server for
> | one of this objects after the age have expired (expecting a 200 and a
> | full refresh) our servers have to recreate the whole objects (some of
> | them taking a lot of CPU and time) even if this is not needed (in
> | normal conditions with conditional GET they will reply 304 with less
> | CPU usage).
> |
> | There is a possible solution to this ? maybe a workaround using VCL ?
> Varnish doesn't do conditional GETs, but you could switch the system
> around and do active cache management where you set the TTL of objects
> to infinity (well, 2 years or something other, high) and let the backend
> use purge to remove objects that should be evicted.
> --
> Tollef Fog Heen
> Redpill Linpro -- Changing the game!
> t: +47 21 54 41 73
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