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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