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From: kunst AT prl DOT philips DOT nl (Pieter Kunst)
Subject: Re: malloc()/free()/heap and thrashing
Sender: news AT prl DOT philips DOT nl (USENET News System)
Organization: Philips Research Laboratories, Eindhoven, The Netherlands
References: <DDCwp4 DOT DxJ AT jade DOT mv DOT net>
Date: Wed, 16 Aug 1995 10:52:42 GMT
Lines: 20
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Dj-Gateway: from newsgroup comp.os.msdos.djgpp

In article <DDCwp4 DOT DxJ AT jade DOT mv DOT net> "A.Appleyard" <A DOT APPLEYARD AT fs2 DOT mt DOT umist DOT ac DOT uk> writes:
>  I have written a text editor AAEMACS in djgpp C++. As it alters lines of the
>text it calls `new' and `delete' a lot (particularly on objects of type `class
>line' (info re a line of the text being edited) and of type `char[]' (the text
>of a line)). I have looked through the source form of malloc() etc and I now
>thus know something of how djgpp's heap handling system works. After I have
>been editing a big file for a while with AAEMACS, the unmistakable symptoms of
>virtual store "store thrashing" start: very slow operation and long stalls
>accompanied by much hard disk noise. I am fairly sure that my program is not
>affected by major "memory leaks" (i.e. store got by `new' being lost sight of
>rather than properly `delete''d).

You might be helped by an article in Dr.Dobbs Journal in the
August 1995 (or September 1995) issue which discusses problems
with this sort of large (de-)allocations. Routines are given to
resolve the problem. Sources can be obtained as well via ftp.mv.com
Mail me if you need more details of the exact issue and title.

Pieter.