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From: Jason Evans <jasone@FreeBSD.org>
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Date: Sat, 28 Apr 2012 11:29:01 -0700
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To: Aleksandr Rybalko <ray@dlink.ua>
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Cc: current@freebsd.org
Subject: Re: <jemalloc>: jemalloc_arena.c:182: Failed assertion: "p[i] == 0"
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On Apr 28, 2012, at 5:09 AM, Aleksandr Rybalko wrote:
>>> On Apr 21, 2012, at 11:54 AM, David Wolfskill wrote:
>>>>=20
>>>> But contrib/jemalloc/src/arena.c contains a function,
>>>> arena_chunk_validate_zeroed():
>>>>=20
>>>>   175 static inline void
>>>>   176 arena_chunk_validate_zeroed(arena_chunk_t *chunk, size_t
>>>> run_ind) 177 {
>>>>   178         size_t i;
>>>>   179         UNUSED size_t *p =3D (size_t *)((uintptr_t)chunk +
>>>> (run_ind << LG_PAGE)); 180
>>>>   181         for (i =3D 0; i < PAGE / sizeof(size_t); i++)
>>>>   182                 assert(p[i] =3D=3D 0);
>>>>   183 }
>=20
> maybe it somehow related to low count of free memory, because I see
> that very frequently on my box. (Atheros AR7242 mips32be with 32M of
> RAM)
>=20
> After "#ifdef" of that function body, box behave good (seems) :)

Yes, arena_chunk_validate_zeroed() (which is debug-only code) has the =
side effect of faulting in untouched pages, so it potentially increases =
physical memory usage.  In practice, this sanity checking has saved =
jemalloc from regressions that would otherwise manifest as mysterious =
application memory corruption (and would have prevented even more =
regressions, had it existed earlier).  You can disable it and many other =
performance-sacrificing debug features by defining MALLOC_PRODUCTION in =
/etc/make.conf.

Jason=