[lttng-dev] Mem leak in lttng_ust lttng_probes_get_event_list()

[Mathieu Desnoyers]

Hi, 

Please open an issue on the bug tracker with all the information requested 
in the bug reporting guidelines. See https://bugs.lttng.org/ 

Thanks, 

Mathieu 

----- On Mar 28, 2016, at 2:09 AM, Aravind HT <aravind.ht at gmail.com> wrote: 

> Hi,
> I have seen that the RES mem from TOP increases over time for an application
> that
> is being traced. When analyzed with valgrind, I see the following

> ==12429== 175,824 bytes in 594 blocks are possibly lost in loss record 30 of 30
> ==12429== at 0x4C29810: calloc (in
> /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
> ==12429== by 0x54AF21E: calloc (in
> /usr/lib64/liblttng-ust-libc-wrapper.so.0.0.0)
> ==12429== by 0x526C27B: lttng_probes_get_event_list (in
> /usr/lib64/liblttng-ust.so.0.0.0)
> ==12429== by 0x526AD9E: ??? (in /usr/lib64/liblttng-ust.so.0.0.0)
> ==12429== by 0x5267FAF: ??? (in /usr/lib64/liblttng-ust.so.0.0.0)
> ==12429== by 0x503CFE2: start_thread (pthread_create.c:312)
> ==12429== by 0x579BAFC: clone (clone.S:111)

> There is a memleak seen when lttng_probes_get_event_list() gets called during
> listing of
> trace points, example "lttng list -u". Each time lttng_probes_get_event_list()
> gets called,
> objd_alloc() is called and a new list of trace points generated in
> lttng_probes_get_event_list()
> and stored.
> This entry in the objd_table is not reused when "lttng list -u" gets called
> again in the future
> and is also not removed until the application exits resulting in memory
> consumption.

> I can see that the objd_table is meant to be used as a cache but somehow the
> full implementation is not present..is this a work still in progress ? If not,
> to solve this, whenever lttng_probes_get_event_list() is called, we could check
> if we have results available in the objd_table from an earlier call for a
> particular owner and name and re-use it.

> Regards,
> Aravind.

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-- 
Mathieu Desnoyers 
EfficiOS Inc. 
http://www.efficios.com 
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