Varnish stuck on most served content

[Hauke Lampe]

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On 30.03.2011 10:51, Diego Roccia wrote:

> Varnish servers are HP DL360 G6 with 66Gb RAM and 4 Quad-Core Xeon CPUs,
> running varnish 2.1.6 (Updated from 2.0.5 1 month ago).

varnish 2.1.6 hasn't been released, yet, AFAIK.

> It's happening often that they freeze serving contents. and I noticed a
> common pattern: the content that get stuck is always one of the most
> served, like a css or js file, or some component of the page layout,

Do you run 2.1.4 or 2.1.5? Is the "freeze" a constant timeout, i.e. does
it eventually deliver the content after the same period of time?

There was a bug in 2.1.4 that could lead to the symptoms you describe.
If the client sent an If-Modified-Since: header and the backend returned
a 304 response, varnish would wait on the backend connection until
"first_byte_timeout" elapsed.

In that case, the following VCL code helps:

sub vcl_pass {
	unset bereq.http.if-modified-since;
	unset bereq.http.if-none-match;
}
http://cfg.openchaos.org/varnish/vcl/common/bug_workaround_2.1.4_304.vcl

See also this thread:
http://www.gossamer-threads.com/lists/varnish/misc/17155#17155



Hauke.


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