[erlang-questions] Tracking memory leaks in NIF/Linkedin drivers with Valgrind (or anything else)

[Lukas Larsson]

Hello,

use the suppress file in erts/emulator/valgrind/suppress.standard to remove
many of the false positive errors. It will not remove all, but many of the
extra errors you see. To remove all you have to use
erts/emulator/valgrind/suppress.patched.3.6.0, but this requires a patched
version of valgrind as the normal suppression syntax was not expressive
enough for our needs.

Lukas


On Sun, Mar 17, 2013 at 10:35 AM, Zabrane Mickael <zabrane3@REDACTED>wrote:

> Hi guys,
>
> I'm trying to use Valgrind to track memory leaks in C NIF/Linkedin drivers.
> For this, I've built a "Debug  Enabled" ERTS with Valgrind and SMP flavor:
> http://www.erlang.org/doc/installation_guide/INSTALL.html
>
> 1/ First attempt: start an Erlang node and turn it off immediately:
>
> $ cerl -valgrind
> [...]
>
> 1> init:stop().
>
> [...]
> ==61127==    at 0xC713: malloc (vg_replace_malloc.c:274)
> ==61127==    by 0x1002C25F0: erts_sys_alloc (in
> /opt/r16b/usr/lib/erlang/erts-5.10.1/bin/beam.valgrind.smp)
> ==61127==    by 0x10000B6B3: erts_alloc (in
> /opt/r16b/usr/lib/erlang/erts-5.10.1/bin/beam.valgrind.smp)
> ==61127==    by 0x10000B5AC: erts_alloc_permanent_cache_aligned (in
> /opt/r16b/usr/lib/erlang/erts-5.10.1/bin/beam.valgrind.smp)
> ==61127==    by 0x1001053E7: init_db (in
> /opt/r16b/usr/lib/erlang/erts-5.10.1/bin/beam.valgrind.smp)
> ==61127==    by 0x10002884B: erl_init (in
> /opt/r16b/usr/lib/erlang/erts-5.10.1/bin/beam.valgrind.smp)
> ==61127==    by 0x10002D273: erl_start (in
> /opt/r16b/usr/lib/erlang/erts-5.10.1/bin/beam.valgrind.smp)
> ==61127==    by 0x10000191F: main (in
> /opt/r16b/usr/lib/erlang/erts-5.10.1/bin/beam.valgrind.smp)
> ==61127==
> ==61127== ERROR SUMMARY: 420 errors from 13 contexts (suppressed: 0 from 0)
>
> 420 errors reported.
>
> Rickard Green explained why Valgrind reported these (false) numbers at:
> http://erlang.org/pipermail/erlang-questions/2010-February/049591.html
>
>
> 2/ Second attempt: simply load "crypto" module and stop it:
>
> $ cerl -valgrind
> [...]
>
> 1> crypto:start().
> 2> crypto:stop().
> ok
> 3>
> =INFO REPORT==== 17-Mar-2013::10:18:26 ===
>     application: crypto
>     exited: stopped
>     type: temporar
> 4> init:stop().
>
> [...]
> ==59400==    at 0xC713: malloc (vg_replace_malloc.c:274)
> ==59400==    by 0x1002C25F0: erts_sys_alloc (in
> /opt/r16b/usr/lib/erlang/erts-5.10.1/bin/beam.valgrind.smp)
> ==59400==    by 0x10000B6B3: erts_alloc (in
> /opt/r16b/usr/lib/erlang/erts-5.10.1/bin/beam.valgrind.smp)
> ==59400==    by 0x10000B5AC: erts_alloc_permanent_cache_aligned (in
> /opt/r16b/usr/lib/erlang/erts-5.10.1/bin/beam.valgrind.smp)
> ==59400==    by 0x1001053E7: init_db (in
> /opt/r16b/usr/lib/erlang/erts-5.10.1/bin/beam.valgrind.smp)
> ==59400==    by 0x10002884B: erl_init (in
> /opt/r16b/usr/lib/erlang/erts-5.10.1/bin/beam.valgrind.smp)
> ==59400==    by 0x10002D273: erl_start (in
> /opt/r16b/usr/lib/erlang/erts-5.10.1/bin/beam.valgrind.smp)
> ==59400==    by 0x10000191F: main (in
> /opt/r16b/usr/lib/erlang/erts-5.10.1/bin/beam.valgrind.smp)
> ==59400==
> ==59400== ERROR SUMMARY: 460 errors from 15 contexts (suppressed: 0 from 0)
>
> Valgrind now reorts 460 errors instead of 420 (see above).
>
> I know, there's no memory leak in "crypto" ... but this doesn't help at
> all. Completely useless.
>
> So, my question is very simple:
> How Valgrind can help me to track memory leaks in my own NIF/linked-in
> drivers then?
> How can I distinguish between these falsy reported numbers and the real
> ones?
>
> Finally, is there any other way than Valgrind?
>
> Regards,
> Zabrane
>
>
>
>
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>
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