From: Andrew Apted <ajapted AT netspace DOT net DOT au>
Date: Mon, 11 Sep 2000 15:54:41 +1000
To: djgpp AT delorie DOT com
Subject: Malloc bug in DJGPP V2.03
Message-ID: <20000911155441.A493@ajax.netspace.net.au>
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Reply-To: djgpp AT delorie DOT com

I'm experiencing a problem with my DJGPP program (glBSP, a nodes
builder for DOOM) where it runs out of memory under DOS, even though
there should be plenty left.  I've memory-profiled the code (under
Linux), and the most it ever uses (not including overheads) is 9 MB,
yet my machine has 64 MB RAM.  This is with DJGPP V2.03.

Below is a test program which can reproduce the problem, which is
similiar to my program (it allocates lots of small objects, around 32
bytes each).  The most it ever uses is 9 MB (excluding overheads in
malloc), yet it always fails here with out of memory before reaching
the end.  The furthest it gets is POS 66, when CWSDPMI's internal heap
parameter is [128], and POS 131 when it is [1024].

Also below is the output of go32-v2 etc...

This is clearly a bug in DJGPP's malloc functions, right ?

Cheers,
__
\/   Andrew Apted  <ajapted AT users DOT sourceforge DOT net>
 

========================================================================

/*
 * TESTMEM
 */
#include <stdio.h>
#include <stdlib.h>

typedef struct blob_s
{
  struct blob_s *next;
  int data[7];
}
blob_t;

int main(void)
{
  int i;
  int actual = 0;
  
  blob_t ** array[16] = { NULL, };

  for (i=0; i < 256000; i++)
  {
    int hi = i % 16;  // breadth first
    int lo = i / 16;

    if ((i % 1000) == 0)
      fprintf(stderr, "POS: %d/%d  ACTUAL: %d\n", i / 1000, 255, actual);

    array[hi] = realloc(array[hi], (lo + 1) * sizeof(blob_t *));
    actual += sizeof(blob_t *);
   
    if (array[hi] == NULL)
    {
      fprintf(stderr, "OUT OF MEMORY ! (realloc)\n");
      return 1;
    }

    array[hi][lo] = calloc(1, sizeof(blob_t));
    actual += sizeof(blob_t);

    if (array[hi][lo] == NULL)
    {
      fprintf(stderr, "OUT OF MEMORY ! (calloc)\n");
      return 1;
    }

    (array[hi][lo])->data[0] = hi;
    (array[hi][lo])->data[1] = lo;
  }

  return 0;
}


========================================================================

output of go32-v2:

go32/v2 version 2.0 built Dec 24 1999 17:46:57
Usage: go32 coff-image [args]
Rename this to go32.exe only if you need a go32 that can run v2 binaries as
 well as v1 binaries (old makefiles).  Put ahead of the old go32 in your PATH
 but do not delete your old go32 - leave it in the PATH after this one.
Set GO32_V2_DEBUG=y in the environment to get verbose output.

DPMI memory available: 64455 Kb
DPMI swap space available: 13617 Kb

output of set:

COMSPEC=C:\COMMAND.COM
PATH=C:\DJGPP\BIN;C:\VIM-5.3;C:\LYNX\LYNX;C:\;C:\DOS;C:\WINDOWS;C:\AMOUSE;C:\UTILS;C:\TC;C:\XTGOLD;C:\ACRODOS
TEMP=C:\TEMP
SCSI_DRIVER=C:\IOMEGA 
SCSI_UTILITY=C:\IOMEGA 
DOOMWADDIR=C:\GAMES\DOOM2
BLASTER=A220 I7 D1 H5 P330 T6
DJGPP=C:\DJGPP\DJGPP.ENV
PROMPT=$p$g
DA=0

config.sys:

DOS=HIGH
DOS=UMB
FILES=40
FCBS=40,0
BUFFERS=40
STACKS=9,256
LASTDRIVE=Z
DEVICE=C:\WINDOWS\HIMEM.SYS
DEVICEHIGH=C:\DOS\ANSI.SYS
DEVICEHIGH=C:\WINDOWS\IFSHLP.SYS
DEVICEHIGH=C:\SBCD\SBIDE.SYS /D:SBPCD /V /P:170,15,376
SHELL=C:COMMAND.COM /E:8192 /P

autoexec.bat:

@ECHO OFF
PATH=C:\DJGPP\BIN;C:\VIM-5.3;C:\LYNX\LYNX;C:\;C:\DOS;C:\WINDOWS;C:\AMOUSE;C:\UTILS;C:\TC;C:\XTGOLD;C:\ACRODOS
SET TEMP=C:\TEMP
SET SCSI_DRIVER=C:\IOMEGA 
SET SCSI_UTILITY=C:\IOMEGA 
SET DOOMWADDIR=C:\GAMES\DOOM2
SET BLASTER=A220 I7 D1 H5 P330 T6
SET DJGPP=C:\DJGPP\DJGPP.ENV
PROMPT $p$g
C:\CDROMDRV\MSCDEX /D:SBPCD /L:R /M:8 /V
C:\DOS\SMARTDRV /X 512 512
DOSKEY /INSERT
MODE CON LINES=50
AMOUSE /R1 /C
ECHO.
MENU