Date: Wed, 15 Jan 2014 21:45:47 +0000 From: Karl Pielorz <kpielorz_lst@tdx.co.uk> To: freebsd-net@freebsd.org Subject: LAST_ACK hanging around / reaping? Message-ID: <39BB47DB91A9375CDA87B5A2@study64.tdx.co.uk>
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Hi, We've a number of FreeBSD 9.2 amd64 systems - recently we've noticed a large number of TCP sessions ending up stuck in 'LAST_ACK' (sometimes this can creep up to many thousands per box). Having dug around - it appears some kind of load balancer at the 'other ends' of these connections isn't handling connection closes too well or something [I don't think it's a FreeBSD issue - it looks like a 'them' issue]. The questions are a) Should we be concerned by constantly having several thousand connections in LAST_ACK b) Is there a sysctl to change how long they'll hang around for? And, more importantly, c) If the system needs these resources - will it reap some of them? (i.e. oldest first or something) - or could they potentially just keep growing in a worst case scenario until something runs out? Thanks, -Karl
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