[Varnish] #849: Session timeout while receiving POST data from client causes multiple broken backend requests

[Varnish]

#849: Session timeout while receiving POST data from client causes multiple
broken backend requests
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 Reporter:  lew                                                                    |        Type:  defect  
   Status:  new                                                                    |    Priority:  normal  
Milestone:                                                                         |   Component:  varnishd
  Version:  2.1.4                                                                  |    Severity:  normal  
 Keywords:  503, post, backend write error: 11 (Resource temporarily unavailable)  |  
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 The default session timeout of 5s was causing a lot of broken POSTs on our
 backends, and 503 errors in our varnish logs (showing up as "backend write
 error: 11 (Resource temporarily unavailable)") - particularly with one of
 our sites that serves mainly mobile clients.

 It appears that during a POST, if the session timeout is exceeded while
 varnish is waiting for data from the client, an incomplete/invalid POST
 request is made to the backend, and then tried again after another 5
 seconds.

 I'm not sure what the 'right' way to handle this would be, but this
 doesn't seem like good behaviour currently.

 For the moment I'm working around the issue by piping POSTs.

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Ticket URL: <http://www.varnish-cache.org/trac/ticket/849>
Varnish <http://varnish-cache.org/>
The Varnish HTTP Accelerator