Backend polling not working

Poul-Henning Kamp phk at
Wed Oct 14 20:34:52 CEST 2009

In message <4AD60D6D.1070909 at>, Izak Burger writes:
>Hi all,
> - Anonymous [14/Oct/2009:18:38:38 +0200] "GET /plonesite 
>HTTP/1.1" 200 0 ""
>Note the zero after the 200 status. I suspect this causes a problem on 
>line 220 of bin/varnishd/cache_backend_poll.c, where rlen is the length 
>of data read from zope:
>         if (rlen == 0)
>                 return;
>The result of this is a sick backend, eg:

Yes, if we get no bytes, we do not accept it as a good probe.

>Using wireshark to log at the network traffic confirms that the HTTP 
>request is sent, but no response, corresponding with the access log.

That would sort of indicate that the problem is on the backend.

You may need to customize the HTTP request used for probing with
the ".request =" line in your backend probe definition, in order
to explain things to your backend.  A Host: header maybe ?


Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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