Date: Thu, 18 Sep 2008 02:05:40 +1000 From: Andrew MacIntyre <andymac@bullseye.apana.org.au> To: freebsd-hackers@freebsd.org Subject: unexpected behaviour of malloc() on 7.0/amd64 Message-ID: <48D12AD4.1000806@bullseye.andymac.org>
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[If this is not an appropriate forum for this query, please suggest
a more appropriate one]
In investigating a Python 2.6rc1 regression test failure on FreeBSD
7.0/amd64, as far as I can tell, malloc() does not return NULL when
available memory (including swap) is exhausted - the process just gets
KILLed.
Using ulimit -v to set a virtual memory use limit below the available
memory does result in malloc() returning NULL when the limit is hit.
The Python regression test concerned does not fail on FreeBSD 7.0/i386,
however the C program below exhibits the unexpected behaviour on both
7.0/amd64 and 7.0/i386. The C program below does behave as
expected on FreeBSD 6.3/i386; I cannot currently test its behaviour on
FreeBSD 6.3/amd64.
I can't see this behaviour documented in the malloc() man page. I
attempted to search the gnats database but the only mention of "malloc"
is not related to this issue and doesn't involve this architecture.
Is this the intended behaviour?
---8<---8<---8<---
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#define CHUNK_SIZE 1024*1024
int main(void)
{
char* t;
char buffer[256];
int i = 0;
while (1)
{
if ((t = malloc(CHUNK_SIZE)) == NULL)
{
sprintf(buffer, "chunks allocated: %d\n", i);
printf(buffer);
break;
}
memset(t, 0, CHUNK_SIZE);
++i;
}
return 0;
}
---8<---8<---8<---
Thanks,
Andrew.
--
-------------------------------------------------------------------------
Andrew I MacIntyre "These thoughts are mine alone..."
E-mail: andymac@bullseye.apana.org.au (pref) | Snail: PO Box 370
andymac@pcug.org.au (alt) | Belconnen ACT 2616
Web: http://www.andymac.org/ | Australia
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