[SR-Users] Memory leak in tm with push notifications

[Ivaylo Markov]

Just in case anyone runs into this kind of problem in the future -
commits 72f5eaeeef0239ebd16a2d645b83e83eb1a2b506 and
5fe2a1a1c67b550431dcae3c98701073f7edd953 (currently in the master branch
only) seem to fix this.


On 05/28/2018 06:01 PM, Ivaylo Markov wrote:
> Hello,
>
> I am trying to set up Kamailio as a push notifications proxy, closely
> following the example in the "Kamailio in a Mobile World" presentation
> (https://www.slideshare.net/FedericoCabiddu/kamailioinamobileworld-51617342).
> I am running Debian 9 and Kamailio 5.1.3 from the official Debian
> repositories.
> I believe the main modules involved in the issue below are tm, tmx, and
> tsilo.
>
> Every call passing through the proxy leads to a small memory leak in the tm
> module - there is a large amount of "delayed free" memory cells from tm's
> internal hash table. At some point the shared memory runs out and Kamailio
> restarts. Using the "kamcmd corex.shm_summary" command I was able to see
> that the top users of shared memory are "tm: h_table.c: build_cell" and
> "core: core/sip_msg_clone.c: sip_msg_shm_clone" with the same allocation
> count.
>
> I experimented with removing different parts of the configuration and
> noticed that commenting out the "t_continue(...)" call in the "PUSHJOIN"
> route
> (see slide #22) prevents the leak from happening. Maybe something in that
> function is incrementing the reference counter to the hash table cell, but
> it is not decrementing the counter when done?
>
> I tried looking around the source code of the tm and tmx modules, but saw
> nothing suspicious. I also tried using gdb with a breakpoint in
> t_continue_helper (tm/t_suspend.c:166) hoping to see what else is accessing
> the htable cell, but was unable to find anything of use.
>
> Has someone encountered anything like this? Can you provide more directions
> on debuggin this? I can provide some bits of configuration, but an entire
> test setup would be rather difficult, unfortunately.
>
> Thank you for your time,
> Ivo
>
>
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