[Varnish] #1754: n_objecthead increase just before oomkill

Varnish varnish-bugs at varnish-cache.org
Mon Feb 22 14:38:45 CET 2016

#1754: n_objecthead increase just before oomkill
 Reporter:  lkarsten  |       Owner:
     Type:  defect    |      Status:  new
 Priority:  normal    |   Milestone:
Component:  varnishd  |     Version:
 Severity:  normal    |  Resolution:
 Keywords:            |

Comment (by slink):

 Just in case this helps, here's some background and a hypothesis: The
 malloc stevedore size you configure is a net value, limiting the total sum
 of all allocations which varnishd may issue to the malloc implementation,
 usually jemalloc. Because varnishd requests allocations of different
 sizes, memory freed by expiring objects or lru nuking them may not be
 usable, by the malloc implementation, to satisfy new allocation requests,
 so the gross amount of memory required may be significantly larger than
 the net value configure. My personal ballpark figure from real life
 experience is a factor of 2-3.
 My hypothesis on what you're seeing is that allocations are satisfied
 until your cache is forced to nuke objects, from which point on you'd see
 the gross/net ratio rise.

Ticket URL: <https://www.varnish-cache.org/trac/ticket/1754#comment:9>
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