Trouble understanding Varnishlog

. gmoniey at gmail.com
Wed Jan 12 08:11:08 CET 2011


Hmm..So essentially the browser cache is preventing Varnish from returning
the result. This definitely makes sense, but I could have sworn that the
X-Varnish header does not show up when I attempt the same request from a
different browser.

It seems regardless of the scenario, even if I clear my browser cache on the
current page, I cannot get the X-Varnish header to show 2 values. I will
keep digging, and see if I can come up with a test case.

On Tue, Jan 11, 2011 at 8:48 AM, Lucas Brasilino
<lucas.brasilino at gmail.com>wrote:

> Hi
>
> > Can someone explain why the object is not being returned as a cached
> object?
>
> Because your client is performing a conditional request and so
> revalidating using
> If-None-Match/Etag headers the already cached object in your machine.
>
> Your client is issuing:
>
> >   15 RxHeader     c If-None-Match: "4ee85970d12afd8992d3dc1651f07b9d"
>
> It means: please send me the object if none match with this Etag value.
>
> Varnish responds:
>
> >   15 TxStatus     c 304
> >   15 TxResponse   c Not Modified
> [...]
> >   15 TxHeader     c ETag: "4ee85970d12afd8992d3dc1651f07b9d"
>
> It means: the object you have is the same one I have.
>
> Transfering an object you already have is a waste of resources :)
>
> regards
> Lucas Brasilino
>
>
>
> > I'm confused around the fact that it says there is a 'hit', but the
> > X-Varnish header only has 1 field.
> > I read that if the Set-Cookie header is sent, then varnish does not cache
> > the object, but I'm pretty sure thats not being sent. Is there another
> rule
> > I'm missing? Thanks.
> > Here is an excerpt of the log:
> >   15 SessionOpen  c 10.0.19.23 59326 :80
> >   15 ReqStart     c 10.0.19.23 59326 1001168302
> >   15 RxRequest    c GET
> >   15 RxURL        c /items?xzy=true
> >   15 RxProtocol   c HTTP/1.1
> >   15 RxHeader     c Host: XYZ
> >   15 RxHeader     c User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X
> > 10.6; en-US; rv:1.9.2.13) Gecko/20101203 Firefox/3.6.13 GTB7.1
> >   15 RxHeader     c Accept:
> > text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
> >   15 RxHeader     c Accept-Language: en-us,en;q=0.5
> >   15 RxHeader     c Accept-Encoding: gzip,deflate
> >   15 RxHeader     c Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
> >   15 RxHeader     c Keep-Alive: 115
> >   15 RxHeader     c Connection: keep-alive
> >   15 RxHeader     c Cookie: __qca=P0-707762352-1283409801091;
> > __utma=182775871.333345873.1284063320.1293103561.1293171223.24;
> >
> __utmz=182775871.1284063320.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none);
> > km_lv=x; km_ai=T7R0VpZshcfDBJiF4n8Edt1vrrI; km_uq=; __utmv=182775871.p
> >   15 RxHeader     c If-None-Match: "4ee85970d12afd8992d3dc1651f07b9d"
> >   15 VCL_call     c recv
> >   15 VCL_return   c lookup
> >   15 VCL_call     c hash
> >   15 VCL_return   c hash
> >   15 Hit          c 1001168004
> >   15 VCL_call     c hit
> >   15 VCL_return   c deliver
> >   15 VCL_call     c deliver
> >   15 VCL_return   c deliver
> >   15 TxProtocol   c HTTP/1.1
> >   15 TxStatus     c 304
> >   15 TxResponse   c Not Modified
> >   15 TxHeader     c Date: Tue, 28 Dec 2010 23:19:53 GMT
> >   15 TxHeader     c Via: 1.1 varnish
> >   15 TxHeader     c X-Varnish: 1001168302
> >   15 TxHeader     c Cache-Control: private, max-age=0, must-revalidate
> >   15 TxHeader     c ETag: "4ee85970d12afd8992d3dc1651f07b9d"
> >   15 TxHeader     c Connection: keep-alive
> >   15 Length       c 0
> >   15 ReqEnd       c 1001168302 1293578393.040635109 1293578393.040782928
> > 0.000112057 0.000097990 0.000049829
> >   15 Debug        c "herding"
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> >
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