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From: CBFalconer <cbfalconer AT yahoo DOT com>
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Subject: Re: New DJGPP hogs memory (was: I need help)
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Date: Fri, 12 Apr 2002 11:53:20 GMT
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Eli Zaretskii wrote:
> 
> > Date: Thu, 11 Apr 2002 16:25:50 -0500
> > From: =?iso-8859-1?Q?=22Jos=E9_L=2E_S=E1nchez_Garrido=22?=
> >   <jlsgarrido AT yahoo DOT com>
> >
> > typedef struct {
> >      char af[10];
> >      char name[10];
> >
> > } record;
> >
> > record **dt, *d;
> >
> > int main (void) {
> >
> >      int count;
> >
> >      for(count=0; count<200000L; count++){
> >          dt=(record **)realloc(dt, (count+1)*sizeof(record *));
> >          d=dt[count];
> >          d=(record *)calloc(10, sizeof(record));
> >      }
> >      return(0);
> > }
> 
> Can you please tell what memory consumption did you see with each one
> of the two versions of the compiler and the library?
> 
> Also, you don't say what compiler switches did you use to compile and
> link the program.
> 
> Anyway, based on looking into this program, I think the changed
> behavior is due to the new version of malloc in libc.a from DJGPP
> v2.03 (so it has nothing to do with the compiler).  The program uses a
> very bad algorithm--reallocating an array on each iteration,
> increasing its size by 1.  It also allocates the memory in lots of
> very small chunks.  So it doesn't surprise me that you run out of free
> memory.
> 
> My recommendation is to modify the algorithm to do a better
> allocation.  If you cannot do that for some reason, you can find the
> old implementation of malloc in djlsr203.zip, file name
> src/libc/ansi/stdlib/fmalloc.c; link it with your program, and you
> will get the old behavior.

He might also try my suggested new malloc package for DJGPP, which
I have mounted at:

   <http://cbfalconer.home.att.net/download/nmalloc.zip>

which, among other things, goes to some pains to minimize the
realloc work.  I have heard nothing back on it from anyone, either
good or bad.

-- 
Chuck F (cbfalconer AT yahoo DOT com) (cbfalconer AT worldnet DOT att DOT net)
   Available for consulting/temporary embedded and systems.
   <http://cbfalconer.home.att.net>  USE worldnet address!