[Varnish] #1236: requests to same url sometimes hang

Varnish varnish-bugs at varnish-cache.org
Mon Dec 10 13:29:01 CET 2012

#1236: requests to same url sometimes hang
 Reporter:  reinhard  |       Owner:
     Type:  defect    |      Status:  closed
 Priority:  normal    |   Milestone:
Component:  varnishd  |     Version:  3.0.3
 Severity:  normal    |  Resolution:  worksforme
 Keywords:            |

Comment (by martin):

 The Varnish min/max thread settings are per thread pool, and the number of
 pools defaults to 2. So you were running with a total minimum of 2, which
 is why the problem showed only at the 3rd request.

 There are a number of runtime parameters that governs thread behavior in
 Varnish. Look in the man page and also in that section of the Varnish
 book. Note also that while Varnish will scale up the number of threads
 automatically when there is consistent thread pressure over time, that
 algorithm isn't designed for these low numbers and a request can be
 starved in that case.

 The default of 1 in the RPMs is just too low to make a running Varnish
 instance, and I believe this has been changed in recent RPMs (but your
 configuration files may stuck form an earlier release?) You should
 configure more like a minimum of 100. Varnish' threads are cheap, and if
 they are not ever being used they hardly take up any resources either.

 Martin Blix Grydeland

Ticket URL: <https://www.varnish-cache.org/trac/ticket/1236#comment:3>
Varnish <https://varnish-cache.org/>
The Varnish HTTP Accelerator

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