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From Chuck Murcko <>
Subject Re: WWW Form Bug Report: "sockets left in FIN_WAIT_2 lingering state" on SunOS 4.x (fwd)
Date Fri, 20 Dec 1996 16:56:21 GMT
With our NMBCLUSTERS set to 4096, we generally restart the machines when we
see 3500 or so FIN_WAIT_2 connects. When we get a bit of time, we'll hack
our own timeout into the TCP stuff, so we don't have to do this.

If your boxes are setup to autoboot on panic, that might see you through the
interim. I'm not sure if/how you do this on SunOS, though. And that doesn't
help if you're running an SSL server.

Rob Hartill liltingly intones:
> Chuck Murcko wrote:
> >> Can this bring down a server ?. I can see lots of these via netstat -a
> >> and one of my machines just died.
> >Answer to first question is, yes, eventually. A connection stuck in FIN_WAIT_2
> >means its mbufs/mbuf_clusters(if system has the second) are not freed yet.
> >Eventually the machine either gets kvm-starved (like SunOS will) or runs
> >out of allocated non-kernel memory or list entries for mbuf_clusters.
> >Without being able to timeout FIN_WAIT_2, like Solaris 2.5+ seems to, the
> >only 'stable' recourse is to allocate a ton of mbufs/mbuf_clusters, and
> >restart the machine or, if you can, the TCP stack (IRIX allows this)
> >periodically. Otherwise you get the odd machine panic.
> Thanks for the info. Looks like I'll have to do a reboot every once in
> a while to clear things.

Chuck Murcko	N2K Inc.	Wayne PA
And now, on a lighter note:
As long as the answer is right, who cares if the question is wrong?

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