[Varnish] #1090: Latency for streaming using byte range requests

Varnish varnish-bugs at varnish-cache.org
Mon Feb 6 12:59:51 CET 2012

#1090: Latency for streaming using byte range requests
  Reporter:  helmer   |        Type:  enhancement
    Status:  closed   |    Priority:  normal     
 Milestone:           |   Component:  varnishd   
   Version:  3.0.2    |    Severity:  normal     
Resolution:  invalid  |    Keywords:             
Changes (by martin):

  * status:  new => closed
  * resolution:  => invalid


 In Varnish 3.0.2s, when a range request is made, the do_stream flag is
 turned off. So the request becomes just like a normal range request
 without any streaming. That is probably the cause of the latency you are
 experiencing, where the entire object will have to be fetched into Varnish
 before the range request can be delivered to the client.

 When the streaming support is released in the main branch of Varnish, we
 plan on having range support for the requests also when doing streaming
 delivery. This will then mean that the requesting client will have a
 streaming delivery of the requested range as the bytes of this range
 becomes available in the cache. The backend(/origin) request will still be
 for the full object.

 There is a patch available for the Varnish 3.0S that was posted on the
 varnish-dev mailing list some time ago by Thomas Souvignet that implements
 this mode as well.

 Your requested feature of byte range requests against the origin server is
 not something that is being worked on, as this would require support for
 partial objects which Varnish doesn't have. So Varnish will continue to
 request the full object from the origin also when streaming.

 As this is a feature request and we only use trac for bugs, I will close
 this ticket.

 Martin Blix Grydeland

Ticket URL: <https://www.varnish-cache.org/trac/ticket/1090#comment:1>
Varnish <https://varnish-cache.org/>
The Varnish HTTP Accelerator

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