Path: utzoo!attcan!uunet!husc6!bu.edu!buengc!bph
From: bph@buengc.BU.EDU (Blair P. Houghton)
Newsgroups: comp.unix.ultrix
Subject: Re: Memory ``leaks'' in DEC servers
Message-ID: <5467@buengc.BU.EDU>
Date: 8 Mar 90 15:00:25 GMT
References: <2973@bacchus.dec.com> <RUSTY.90Mar7105635@garnet.berkeley.edu>
Reply-To: bph@buengc.bu.edu (Blair P. Houghton)
Followup-To: comp.unix.ultrix
Organization: Boston Univ. Col. of Eng.
Lines: 24

In article <RUSTY.90Mar7105635@garnet.berkeley.edu> rusty@garnet.berkeley.edu (rusty wright) writes:
>In article <2973@bacchus.dec.com> joel@pandora.pa.dec.com (Joel McCormack) writes:
>   (1) There is no way to give memory back to the kernel once it is
>   allocated.  So killing off all of your applications will not reduce the
>   total amount of memory consumed by the server.  It should reduce the
>   amount of memory needed to be resident.
>
>This isn't true, a program can give memory back to the kernel once it
>is allocated; do "man brk".

While it is true that you can use brk(addr) to return data
space to the system, you have to be sure that you don't
need anything above addr before you do it.  Joel said he
didn't know of any X servers that do garbage collection and
compaction, so what you end up with are long stretches of
mostly free memory with a few valid bytes hanging around.
You can only brk() back down to the highest of these.

The question is, why aren't there any garbage collectors in
X servers?

				--Blair
				  "Dare I crosspost to comp.windows.x?
				   No, I durn't..."