[Varnish] #1495: WRK_SumStat lock contention with high number of thread pools

[Varnish]

#1495: WRK_SumStat lock contention with high number of thread pools
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 Reporter:  dormando  |       Type:  defect
   Status:  new       |   Priority:  normal
Milestone:            |  Component:  build
  Version:  unknown   |   Severity:  normal
 Keywords:            |
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 May also be increasing just as active threads increase.

 Increasing thread_stats_rate did improve speed but not as much as I
 expected.

 More context: https://gist.github.com/dormando/05689cdc5709881b382a

 Can run tests or provide more details if needed.

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Ticket URL: <https://www.varnish-cache.org/trac/ticket/1495>
Varnish <https://varnish-cache.org/>
The Varnish HTTP Accelerator