Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!sun-barr!ames!pacbell!lll-winken!gauss.llnl.gov!casey
From: casey@gauss.llnl.gov (Casey Leedom)
Newsgroups: comp.protocols.tcp-ip
Subject: Re:  SO_KEEPALIVE considered harmful?
Message-ID: <25761@lll-winken.UUCP>
Date: 24 May 89 02:37:13 GMT
References: <8905231641.AA25794@ucbvax.Berkeley.EDU>
Sender: usenet@lll-winken.UUCP
Reply-To: casey@lll-crg.llnl.gov.UUCP (Casey Leedom)
Organization: Lawrence Livermore National Laboratory
Lines: 27

| From: dcrocker@AHWAHNEE.STANFORD.EDU (Dave Crocker)
| 
| If the group proposing the use of Keepalives has already gone through the
| exercise of convincing themselves that critical functionality will be
| lost if they are not used, then I hope the next question was/is how to
| minimize their use.

  I think that the big problem that Robert may be trying to deal with is
server crashes.  (Correct me if I'm totally off the deep end Robert.)
Currently, when an X.V11R3 server crashes or simply exits for normal
reasons and there are still clients using it, those clients will
(typically) lay around forever because they never try to contact the
server on their own and they never receive anything from the [now
defunct] server.  [One exception to this is the "xperfmon" client which
periodically attempts to update a system statistics display.  When the X
server disappears, xperfmon starts gobbling up reams of CPU time, not
recognizing the closed connection for what it is.  But this is just a
coding error.]

  I would say that any X client which only tries to use its connection to
the server in response to input from the server should run with
keep-alives on the connection.  Otherwise it will never exit.  I'm
constantly having to go around killing off abandoned xterms because some
people just can't remember to terminate all their client before shutting
down their server.

Casey