[Varnish] #748: sess_timeout incorrectly used for in-flight requests

Varnish varnish-bugs at varnish-cache.org
Thu Aug 5 06:13:17 CEST 2010

#748: sess_timeout incorrectly used for in-flight requests
 Reporter:  xb95   |        Type:  defect
   Status:  new    |    Priority:  normal
Milestone:         |   Component:  build 
  Version:  2.1.0  |    Severity:  minor 
 Keywords:         |  
 sess_timeout, as per the docs:
 "Idle timeout for persistent sessions. If a HTTP request has not been
 received in this many seconds, the session is closed."

 In reality, (as far as I can tell from some strace debugging) this
 variable is used to set the SO_RCVTIMEO on the bereq when Varnish is
 waiting for a response from the backend.  This seems to lead to "backend
 write error: 11" errors when the backend does not respond fast enough,
 causing Varnish to return a 503 "backend unavailable" message.

 Either the documentation is wrong and sess_timeout is intended to be a
 backend response timeout, or we should have some sort of backend response
 timeout variable to tune separately.

 This is as per version 2.1.0, but a look at the changelog doesn't indicate
 any changes that seem to address this.

Ticket URL: <http://www.varnish-cache.org/ticket/748>
Varnish <http://varnish-cache.org/>
The Varnish HTTP Accelerator

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