[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  |       Owner:  Poul-Henning Kamp <phk@…>
     Type:  defect    |      Status:  closed
 Priority:  normal    |   Milestone:
Component:  varnishd  |     Version:  unknown
 Severity:  normal    |  Resolution:  fixed
 Keywords:            |
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Changes (by Poul-Henning Kamp <phk@…>):

 * status:  new => closed
 * owner:   => Poul-Henning Kamp <phk@…>
 * resolution:   => fixed


Comment:

 In [38ee7837bb5129276e4c75d45a554fb56ddbeb37]:
 {{{
 #!CommitTicketReference repository=""
 revision="38ee7837bb5129276e4c75d45a554fb56ddbeb37"
 The mutex protecting summing of stats into the global VSC counters
 is a contention point and scales negatively with number of thread-pools.

 Sum into a per-pool dstat structure instead, and have the first
 idle thread summ that into the global counters without blocking the
 pool mutex.

 Fixes   #1495

 (I hope)
 }}}

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Ticket URL: <https://www.varnish-cache.org/trac/ticket/1495#comment:2>
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