[Varnish] #897: sess_mem "leak" on hyper-threaded cpu

[Varnish]

#897: sess_mem "leak" on hyper-threaded cpu
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 Reporter:  askalski                             |        Owner:  phk   
     Type:  defect                               |       Status:  closed
 Priority:  normal                               |    Milestone:        
Component:  varnishd                             |      Version:  3.0.2 
 Severity:  major                                |   Resolution:  fixed 
 Keywords:  sess_mem leak n_sess race condition  |  
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Changes (by Martin Blix Grydeland <martin@…>):

  * status:  reopened => closed
  * resolution:  => fixed


Comment:

 (In [596246ea3fc36847dc27d1672dd37a8fef817ac5]) Make n_sess be the
 difference between in use and released session
 objects.

 This avoids a memory race on the n_sess counter, which can lead to
 excessive session object allocation. Keeping the counters of in use
 and released separate allows the acceptor to continue to run lockless.

 Fixes: #897

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Ticket URL: <https://www.varnish-cache.org/trac/ticket/897#comment:12>
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