Unconditional GETs and 304 from backend servers

Tollef Fog Heen tfheen at redpill-linpro.com
Mon Jan 4 10:48:11 CET 2010

]] 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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