Problem with 304 responses from backend (results in 503 errors)

Christian Scholz mrtopf at
Sun Dec 19 18:23:50 CET 2010


I am using varnishd (varnish-2.1.4 SVN 5447M) and I am having a
problem if the backend returns a 304 error as this results in varnish
hanging for 60s and then returning a 503.

I put the logfile at, and
the relevant lines are this (done with varnishlog -o):

14 ObjProtocol  c HTTP/1.1
14 ObjStatus    c 304
14 ObjResponse  c Not Modified
14 ObjHeader    c Server: Zope/(2.12.11, python 2.6.5, linux2) ZServer/1.1
14 ObjHeader    c Date: Sun, 19 Dec 2010 17:02:18 GMT
14 ObjHeader    c X-Cache-Rule: product.simplelayout
14 ObjHeader    c ETag: |Authenticated;Internal;Member|****|1292695386.0
14 ObjHeader    c X-Cache-Operation:
14 ObjHeader    c X-Varnish-Action: FETCH (pass - not cacheable)
14 FetchError   c eof read_error: 11
14 VCL_call     c error deliver
14 VCL_call     c deliver deliver
14 TxProtocol   c HTTP/1.1
14 TxStatus     c 503
14 TxResponse   c Service Unavailable

So the backend returns a 304 without a content-length header.

You can see my varnish vcl here:

The result of this is that every second reload of a page results in a 503.

Does somebody know if I am doing something wrong or if that's a bug
either in varnish or Plone?

Thanks in advance!


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