Using varnish to increase the cache time of slow pages
TFigueiro at au.westfield.com
Mon Mar 12 23:21:50 CET 2012
Hi, Jonathan. Thanks for the feedback!
> However, I have a couple of quibbles with this *implementation*:
> 1) Every bit of logic you embed into VCL is something you have to work at
It's fair to note that other web framework engines seem to use the X-Runtime header for this purpose.
But yes, I agree, you might have to implement that in your backend.
> munging the TTL in VCL!), fixing your back-end's code so it outputs the
> right caching headers, possibly using the same methodology, is a more
> significant win. IMHO :-)
Ah! No need to put salt in our sores. :)
What typically happens is that new features are prioritised over improving performance. I think this is a sad reality in many companies.
What little effort goes into performance ends-up being "spread" across the application. If you have editors complaining about content freshness you can now target these specific pages.
> 2) From a more concrete PoV, I'm not sure this code copes well with
> content the back-end explicitly marks as non-cachable (i.e. ttl=0).
We have specific code in our VCL for this and assumed everyone else does. I should have mentioned that when this excerpt runs we have already 'passed' content which is not cacheable.
> Anyway, thanks for introducing the concept! Sorry if this looks a bit
> negative - it's not really meant to come over as such :-)
Not negative at all, they were all good points and I appreciate you taking the time to ping back.
This electronic mail message, including any and/or all attachments, is for the sole use of the intended recipient(s), and may contain confidential and/or privileged information, pertaining to business conducted under the direction and supervision of the sending organization. All electronic mail messages, which may have been established as expressed views and/or opinions (stated either within the electronic mail message or any of its attachments), are left to the sole responsibility of that of the sender, and are not necessarily attributed to the sending organization. Unauthorized interception, review, use, disclosure or distribution of any such information contained within this electronic mail message and/or its attachment(s), is (are) strictly prohibited. If you are not the intended recipient, please contact the sender by replying to this electronic mail message, along with the destruction all copies of the original electronic mail message (along with any attachments).
More information about the varnish-misc