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From: ddb@ns.network.com (David Dyer-Bennet)
Newsgroups: comp.lang.c
Subject: Re: What if I don't free() all my dynamically allocated memory?
Keywords: Not on a Unix system, that is.
Message-ID: <1370@ns.network.com>
Date: 9 May 89 18:36:40 GMT
References: <2580@ssc-vax.UUCP> <386@nbires.nbi.com> <1384@dukeac.UUCP> <2239@athertn.Atherton.COM> <1391@dukeac.UUCP> <543@laic.UUCP>
Sender: ddb@ns.network.com (David Dyer-Bennet)
Reply-To: ddb@ns.UUCP (David Dyer-Bennet)
Organization: Terrabit Software
Lines: 26

In article <543@laic.UUCP> darin@nova.UUCP (Darin Johnson) writes:
:The only thing that makes most OS's clear allocated memory on exit, is
:virtual memory.  Without it, the OS will have to go to a lot of work to
:keep track of the memory you allocated.  If you allocate averything off
:of a stack, then it is no big deal, but what if you want to allocate something
:that won't fit in your stack space?  Believe it or not, there are a lot
:of machines that don't have virtual memory, or keep track of the memory
:you allocate, or have a near infinite upper bound on the stack?  I believe
:most small computers fall into this category, especially those that
:multitask and/or support desktop thingies and stay resident thingies.

TSS/8 on a PDP-8/I, RSTS on a pdp-11, TOPS-10 and TOPS-20 on KL-10
hardware, MS-DOS, and all versions of Unix I have seen do not display
the behavior you describe as common above.  Only Tops-10, Tops-20, and
a few of the unixes are virtual-memory systems.  Most of these probably
count as "small computers" by today's standards :-)

In my experience it's the presence of a "process" abstraction in the
operating system that allows clean handling of un-freed memory at
process termination.  Even the 8088-based Unix was able to handle that.

-- 
David Dyer-Bennet, ddb@terrabit.fidonet.org, or ddb@ns.network.com
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