Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!uakari.primate.wisc.edu!gem.mps.ohio-state.edu!tut.cis.ohio-state.edu!purdue!mentor.cc.purdue.edu!dls
From: dls@mentor.cc.purdue.edu (David L Stevens)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: 'shutdown' vs. 'close' to free resources?
Keywords: tcp shutdown socket
Message-ID: <4577@mentor.cc.purdue.edu>
Date: 18 Oct 89 17:25:28 GMT
References: <239@melpar.UUCP>
Reply-To: dls@mentor.cc.purdue.edu (David L Stevens)
Distribution: usa
Organization: PUCC UNIX Group
Lines: 13


	UNIX's shutdown(2) corresponds to the TCP ABORT function and is NOT
generally a good way to free socket resources, unless you have another way of
determining (through the upper level protocol) that no more data need be sent.
	In particular, if you do a shutdown(2) after you've written your data,
if the data is still in a kernel buffer on your end waiting to be sent, it will
be discarded and the other guy will never see it. Close(2) is the only way to
guarantee delivery of all pending written data short of doing this in the upper
protocol.
	In other words, close(2) isn't hanging onto everything just to be mean
to you... :-) It's where some of TCP's reliability comes from.
-- 
					+-DLS  (dls@mentor.cc.purdue.edu)