Date: Thu, 11 Jul 2013 17:35:04 +0400 From: Gleb Smirnoff <glebius@FreeBSD.org> To: Andre Oppermann <andre@freebsd.org> Cc: freebsd-net@FreeBSD.org, Andriy Gapon <avg@FreeBSD.org> Subject: Re: Listen queue overflow: N already in queue awaiting acceptance Message-ID: <20130711133504.GB67810@FreeBSD.org> In-Reply-To: <51DE5C8C.3090404@freebsd.org> References: <51DE591E.7040405@FreeBSD.org> <51DE5C8C.3090404@freebsd.org>
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On Thu, Jul 11, 2013 at 09:19:40AM +0200, Andre Oppermann wrote: A> On 11.07.2013 09:05, Andriy Gapon wrote: A> > kernel: sonewconn: pcb 0xfffffe0047db3930: Listen queue overflow: 193 already in A> > queue awaiting acceptance A> > last message repeated 113 times A> > last message repeated 518 times A> > last message repeated 2413 times A> > last message repeated 2041 times A> > last message repeated 1741 times A> > last message repeated 1543 times A> > last message repeated 1283 times A> > last message repeated 1178 times A> > last message repeated 1020 times A> > ... A> > A> > What does this messages mean? A> A> That your server process lagging behind in accepting new connections and a A> quite a number of them get aborted due to a backlogged listen queue. A> A> Making the accept queue longer doesn't help, it's user-space that can't keep A> up with the rate of new incoming connections. A> A> You can either reduce the rate of new incoming connections, optimize your A> server process to accept more connections in the same time, or get a beefier A> machine. A> A> > Is it really that important to be printed? A> A> The log messages are at DEBUG level. People probably want to know about A> their server not keeping up and throwing incoming connection attempts away. A> A> > Finally, why is it not throttled? A> A> The frequency it happens with is important to determine if this is only A> a temporary spike (micro-burst) or persistent condition. IMO, this should be a single counter accessible via sysctl, with no printf(). Those, who need details on whether this is micro-burst or persistent condition, can run monitoring software that draws plots. -- Totus tuus, Glebius.
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