Re: malloc() fails: 32MB heap limit and how to work around?

Okay, so let me rephrase my problem: As soon as I use the -Zcrtdll 
option, the program
cannot malloc() more than 32MB memory.

I used the following test program:

#include <stdio.h>
#include <malloc.h>
#include <umalloc.h>

#include <unistd.h>

void us(void) {
  _HEAPSTATS hs;

  if (0==_ustats(_udefault(NULL),&hs))
    printf ("%lu %lu\n",
            (unsigned long)(hs._provided), (unsigned long)(hs._used));
  else
    printf("heapstatus error\n");   
}

int main (void)
{
  void *p;
  int i;
  /* Avoid deadlock due to buffer allocation in printf()! */
  setvbuf (stdout, NULL, _IOLBF, BUFSIZ);

  for (i=0; i<50; i++) {
    p=malloc(10000000);
    if (NULL==p) printf("%i: malloc failed\n",i);
    us();
  }
  return 0;
}

When compiling with "gcc proggi.c" it exhausts the user memory after 29 
mallocs()
...
298516032 290005120
29: malloc failed
301989440 290005120
30: malloc failed
...

When compiling with "gcc proggi.c -Zcrtdll" it cannot malloc more than 32MB:

10092160 10005144
20119168 20005144
30146176 30005144
3: malloc failed
33554048 30005144
4: malloc failed
....

Any clues/ workarounds?

Thomas.

Ilya Zakharevich wrote:

>On Sun, Oct 19, 2003 at 11:05:14PM +0200, Thomas Hoffmann wrote:
>  
>
>>That's an EMX feature. Usually EMX applications are limited to
>>using a 32MB heap
>>    
>>
>
>Bullocks.  EMX programs can use as much memory as is available via
>low-memory user memory space.
>
>  
>
>>_UF_SBRK_CONTIGUOUS sbrk() always allocates contiguous memory; the size 
>>of the heap is
>>limited to the initial heap size.  This is the initial setting; however, 
>>the malloc() implementation of emx
>>selects _UF_SBRK_ARBITRARY
>>    
>>
>
>Actually, this means that the default for programs which *do not* use
>EMX's malloc() (and do not call CRT library entry points which use
>EMX's malloc()) is *not* _UF_SBRK_ARBITRARY.
>
>_UF_SBRK_ARBITRARY is set during the first invocation of malloc().
>E.g., all Perl (which uses its own malloc()) needs to do is
>
>    _uflags (_UF_SBRK_MODEL, _UF_SBRK_ARBITRARY);
>
>Hope this helps,
>Ilya
>
>_______________________________________________
>Emx mailing list
>Emx-yH06IGssc98i5CQI31g/[email protected]
>http://xfreeos2.dyndns.org/mailman/listinfo/emx
>
>  
>

-- 
Thomas Hoffmann                                    Telephone: 49-351-4598831
[email protected]                                       Dresden, Germany

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