Re: pjsip Digest, Vol 172, Issue 2, Memory Leak from pjmedia_snd_port_create2

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Hello Mario,

at least you should be able to easily verify if memory fragmentation is
the root cause or not: just call malloc_trim() - either from your
program or manually from GDB - after you see the leak. "malloc_trim()"
walks down the whole heap to find unused memory chunks and so should be
able to return the memory back to the OS even if you necounter memory
fragmentation. If the RSS memory size of your program goes back to
normal after calling malloc_trim(), you are dealing with memory
fragmentation. Otherwise it's likely a real leak.


Best regards,

   Christian

On 2/4/22 6:19 PM, MÅrîØ Raƒƒin wrote:
Dear Members,
    I further investigated the memory leak I am experimentig.

The steps to get this leak are the following:

1. create a cache pool from the factory using "pj_pool_create"
2. create a media port to generate a 40 ms sine wave samples e record
from microphone using "pjmedia_port_info_init"
3. create a sound port "pjmedia_snd_port_create2"
4. connect the the media port to the sound device
"pjmedia_snd_port_connect"
5. after the 40ms tone is output and the echo has been received
disconnect the port "pjmedia_snd_port_disconnect"
6. release the pool (pj_pool_release)

Calling this each minute the heap size increases until I get in one
day, an out of memory (at the beninning I exploit only 3.3% of the
available memory).
In this code all the memory is allocated int the pool using
pj_pool_alloc. I also tried to remove all the calls to the ALSA driver
with any improvement.

What I observed is that if I only allocate/deallocate the media port
the leak is not present. It start when I call
"pjmedia_snd_port_create2" even if I don't connect the port to the
sound device.

Moreover dumping the cache pools I find their size is stable and
reasonable.
Nevertheless, pmap shows an increasing size of the heap used by the
process.
Andreas Wehrmann suggested a possible memory fragmentation issue but I
am not sure it could cause such a dramatic memory waste and I can not
explain why pjmedia_snd_port_create2 create this issue while the
allocation of the media port, which is more demanding, does not
produce the issue.

The alsa audio device starts a thread which captures the audio frames
and sends frames to the audio dev.  I have some suspect on the stack
allocation of this thread but it should use the memory pools (I use
"pj_thread_create") so everithing should be released with the pool.

I have run out the ideas on the possible cause of this leak, every
hint will be extremely appreciated.

mario


Il 29/01/2022 09:30, pjsip-request@xxxxxxxxxxxxxxx ha scritto:
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Today's Topics:

    1. Memory Leak with alsa driver (MÅrîØ Raƒƒin)
    2. Re: Memory Leak with alsa driver (Andreas Wehrmann)


----------------------------------------------------------------------

Message: 1
Date: Fri, 28 Jan 2022 18:24:00 +0100
From: MÅrîØ Raƒƒin <raffin@xxxxxxxxxxxxxx>
Subject:  Memory Leak with alsa driver
To: pjsip@xxxxxxxxxxxxxxx
Message-ID: <7244f6b2-38e6-390c-06dc-35c2e205ecf7@xxxxxxxxxxxxxx>
Content-Type: multipart/alternative;
    boundary="------------Id3V26CN7btFojAhitK5fSdz"

Dear All,
      I am debugging an application which exploit the pjsip stack.
I noticed a memory leak when using the alsa driver since each time I
open and close the audio, pmap shows and increment on the user memory
(4-12 KB each time).

Apparently this increment is in the heap region:

20608:   /home/root/easysip
Address   Kbytes     RSS   Dirty Mode  Mapping
00010000    1324    1324      28 r-x-- /home/root/easysip
0016a000       4       4       4 r---- /home/root/easysip
0016b000      20      20      16 rw--- /home/root/easysip
00170000     524     464     464 rw---   [ anon ] <--------increment
on this area
b09da000       4       0       0 -----   [ anon ]
b09db000    8192       8       8 rw---   [ anon ]
b39d8000       4       0       0 -----   [ anon ]
b39d9000    8192      16      16 rw---   [ anon ]
b41d9000       4       0       0 -----   [ anon ]
b41da000    8192      16      16 rw---   [ anon ]
b49da000       4       0       0 -----   [ anon ]
b49db000    8192      12      12 rw---   [ anon ]
....
b549b000     332     332       0 r-x--
/usr/lib/pulseaudio/libpulsecommon-12.2.so
b54ee000      64       0       0 -----
/usr/lib/pulseaudio/libpulsecommon-12.2.so
b54fe000       4       4       4 r----
/usr/lib/pulseaudio/libpulsecommon-12.2.so
b54ff000       4       4       4 rw---
/usr/lib/pulseaudio/libpulsecommon-12.2.so
b5500000     952     836     836 rw---   [ anon ] <--------then
increment on this area
b55ee000      72       0       0 -----   [ anon ]
...

I have spent 10 day looking for a trouble in the code which manages
the ALSA but everything looks fine.
In the code there aren't malloc or calloc, all the memory is managed
by the pj_pool and the pools used during the audio stream are released.

I noticed that the first 5/6 times I open ond close the audio, the
memory does not grow, then it starts to increase. This behaviour make
me think to a memory pool which first uses its allocated space and
then start allocating more space.

However, the pj_pool_factory_dump() shows that the pools size is
stable and there are not pools growing. I use a single pool factory

The only functions which allocate ram outside the pj_pools are
snd_pcm_open() which is followed by snd_pcm_close() and
snd_pcm_(hw|sw)_params_malloc() which is always followed by the
snd_pcm_(hw|sw)_params_free()

The memory area where the pools are allocated is the same I see
growing with pmap.
I wonder wether there is some wrong use of the memory pools which
could cause this kind of problems (for instance, what happen if I
create two time a pool with the same name? however I didn't found
this in my code ).

Is it possible that when the memory of the pool is released, for some
reason the system retain it?

Every idea that could help me to debug this issue will be very
appreciated.

Thank you.
Best regards.
Mario


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