Date: Fri, 11 Jun 2010 21:23:43 +0200 From: Vikash Badal <Vikash.Badal@is.co.za> To: "freebsd-questions@freebsd.org" <freebsd-questions@freebsd.org> Subject: threads and malloc/free on freebsd 8.0 Message-ID: <9B425C841283E0418B1825D40CBCFA613D9E3CA643@ZABRYSVISEXMBX1.af.didata.local>
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Greetings.
I have a thread socket application that seems to be behaving strangely
In a worker thread, I have the following.
<CODE>-----------
=20 LogMessage(DEBUG_0, "allocated %ld", malloc_usable_size(inst));
=20 =20
=20 free(inst);
=20 =20
=20 LogMessage(DEBUG_0, "after free allocated %ld", malloc_usable_size(i=
nst));
=20 free(inst);
=20 =20
=20 return 0;
-----------</CODE>
output> allocated 2304
output> after free allocated 2304
from playing around, this should have segfaulted but it didn't:
if I try this from a non threaded, non socket code:
<CODE>------------------
=20 char *z;
=20 z =3D (char*)malloc(1000);
=20 printf("malloc is %ld\n", malloc_usable_size(z));
=20 free(z);
=20 printf("after malloc is %ld\n", malloc_usable_size(z));
------------------</CODE>
Output> malloc is 1024
Output> Segmentation fault (core dumped)
Can anyone enlighten me ? why did the 2nd free not cause a segmentation f=
ault ?
If im not clear, please forgive me.
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