(gdb) bt
#0  pubsub_on_server_timeout (evsub=<optimized out>) at res_pjsip_pubsub.c:1238
#1  0x00007ffff3d6d6f5 in on_timer () from /usr/lib/libpjsip-simple.so.2
#2  0x00007ffff19ad5a7 in pj_timer_heap_poll () from /usr/lib/libpj.so.2
#3  0x00007ffff3b33964 in pjsip_endpt_handle_events2 () from /usr/lib/libpjsip.so.2
#4  0x00007ffff44514d0 in monitor_thread_exec (endpt=<optimized out>) at res_pjsip.c:1942
#5  0x00007ffff199d55a in thread_main () from /usr/lib/libpj.so.2
#6  0x00007ffff6501b50 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
#7  0x00007ffff792ba7d in clone () from /lib/x86_64-linux-gnu/libc.so.6
#8  0x0000000000000000 in ?? ()
(gdb) thread 17
[Switching to thread 17 (Thread 0x7fffeec20700 (LWP 25966))]
#0  pubsub_on_server_timeout (evsub=<optimized out>) at res_pjsip_pubsub.c:1238
1238            ast_sip_push_task(sub->serializer, serialized_pubsub_on_server_timeout, sub);
(gdb) print *evsub
value has been optimized out
(gdb) print sub
$11 = (struct ast_sip_subscription *) 0x0