varnish not bundling simultaneous requests?

Kristian Lyngstol kristian at
Fri Apr 29 10:31:23 CEST 2011

On Thu, Apr 28, 2011 at 06:34:11PM -0700, Rich Rauenzahn wrote:
> I just ran a test where I requested (via curl) the same resource in
> parallel from varnish, and I got multiple backend requests (I checked
> my apache log).
> Could it be that there is a small race condition that is possible to
> hit such that two backend requests get initiated if they are close
> enough in time?  (my test was a curl ... & curl ... & -- if I do it by
> hand, which is slower, they seem to get bundled.)

That sounds unlikely. It's more likely that the object isn't being
cached at all. Can you provide varnishlog output from a test like that?

Also, setting obj.ttl to 1d in vcl_hit means never expiring objects, as
you reset the ttl every time they are accessed... So the only way they
are expired is if they aren't requested for a day.

- Kristian

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