[Varnish] #897: sess_mem "leak" on hyper-threaded cpu
Varnish
varnish-bugs at varnish-cache.org
Wed Apr 13 18:52:42 CEST 2011
#897: sess_mem "leak" on hyper-threaded cpu
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Reporter: askalski | Type: defect
Status: new | Priority: normal
Milestone: | Component: build
Version: trunk | Severity: major
Keywords: sess_mem leak n_sess race condition |
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Comment(by askalski):
Attached is a patch that solves the race condition without locking in the
acceptor thread (thanks to Mithrandir for pointing that out.) It does so
by splitting the "n_sess" statistic into "n_sess_new" (no mutex), and
"n_sess_delete" (mutex, worker). The worker threads then calculate the
number of outstanding sessions by subtracting. I didn't bother checking
for counter overflow, because it would take 1000 years at a rate of 500+
million sessions per second for that to happen.
--
Ticket URL: <http://www.varnish-cache.org/trac/ticket/897#comment:3>
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