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Date:      Wed, 09 Jun 1999 10:55:00 -0700
From:      Ted Faber <faber@ISI.EDU>
To:        Dan Moschuk <dan@trinsec.com>
Cc:        hackers@freebsd.org
Subject:   Re: hundreds of sockets stuck in TIME_WAIT 
Message-ID:  <199906091755.KAA13333@boreas.isi.edu>
In-Reply-To: Your message of "Wed, 09 Jun 1999 11:59:51 EDT." <19990609115951.A79834@trinsec.com> 

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Dan Moschuk wrote:
>
>I noticed on a very high traffic'd webserver, I have just over 4000 sockets
>stuck in the TIME_WAIT state.  Ideally, I want to "bend" the RFC a bit and
>close the descriptor before it hits that state, or, ignore the 2MSL wait
>when it enters that state.  

Are they casuing you a problem?  If so, what?  I'm interested because
I wrote a paper about this problem
(http://www.isi.edu/~faber/pubs/html/infocom99/ for the html,
http://www.isi.edu/~faber/pubs/time_wait.ps for postscript) and
various people have told me that although the PCBs pile up, the
performance effects are minimal in a reasonable OS (specifically in
FreeBSD).

And more directly for you, if they're not harming your performance, I
wouldn't do *anything*.  They do serve a purpose.

>
>I take it there is no sysctl switch to trigger this, so, am I going 
>kernel diving?

I don't think there is one.  Although I don't think it's a good idea
to turn off the TW state, I think it's pretty easy to do so.

I'm going to be away from my email for a few days, so don't be
surprised if you respond and don't hear from me immediately.  If folks
have evidence that accumulating TW states cause a performance problem
(although I doubt they do), I would love to know about it.



- -- 
- ----------------------------------------------------------------------
Ted Faber                                                faber@isi.edu
USC/ISI Computer Scientist                   http://www.isi.edu/~faber
(310) 822-1511 x190      PGP Key: http://www.isi.edu/~faber/pubkey.asc


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