Xref:	news2.mv.net comp.os.msdos.djgpp:807
From:	beale AT leland DOT Stanford DOT EDU (John Beale)
Newsgroups:	comp.os.msdos.djgpp
Subject:	malloc/free ends up fragmenting dynamic memory?
Date:	5 Feb 1996 13:26:32 -0800
Organization:	Stanford University, CA 94305, USA
Lines:	21
Message-ID:	<4f5sm8$2kt@cardinal1.Stanford.EDU>
NNTP-Posting-Host:	cardinal1.stanford.edu
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

I don't know if this problem is specific to DJGPP or generic to gcc or all
C compilers, can anyone advise?

I'm using DJGPP v2.0 beta 4 under DOS 5 with cwsdpmi.exe. I observe
that my program, which dynamically allocates and frees (malloc() and
free()) many large and different-sized arrays, eventually ends up not being
able to malloc even a mid-sized array when it used to be able to malloc
many of that size. Quitting the program and restarting solves the problem.

I am guessing that the many malloc/free operations fragments the memory
store analgous to hard disk filesystem fragmentation with many saves and
deletes, such that a contiguous memory segment for a large malloc() can no
longer be found. Is there a malloc_unfragment() command or equivalent?  How
do other people handle this problem?

Thanks very much for any assistance.

John Beale   -------------------------  beale AT jumpjibe DOT stanford DOT edu
--------------------------    http://jump.stanford.edu:8080/beale/

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