recording_thread can not unlock session when record application is executed on hangup at the same time.

[Django-xinfa]

Occasionally, some calls can not be released. I tracked the logs with the code and found this issue. Like recording_thread seems to be waiting for a signal so much that it can't be unlocked when record application is executed on hangup at the same time.

My vesion is based on 1.10.9. But I added some logs so that the number of lines of code wasn't exactly the same as the standard version.

I compared the code for 1.10.12 and found no changes in recording_thread. I don't know why the code doesn't call "switch_thread_cond_wait" before making a judgment on whether the session is valid or not.

Here's some useful output information by "pstack":

Thread 5 (Thread 0x7f1d10e35700 (LWP 61196)):
#0 0x00007f1d92e7539e in pthread_rwlock_wrlock () from /lib64/libpthread.so.0
#1 0x00007f1d95fa9c89 in fspr_thread_rwlock_wrlock (rwlock=) at locks/unix/thread_rwlock.c:97
#2 0x00007f1d95c65645 in switch_thread_rwlock_wrlock (rwlock=) at src/switch_apr.c:253
#3 0x00007f1d95ca3dbc in switch_core_session_write_lock (session=) at src/switch_core_rwlock.c:156
#4 0x00007f1d95c98683 in switch_core_session_thread (thread=, obj=) at src/switch_core_session.c:1747
#5 0x00007f1d95c93d5a in switch_core_session_thread_pool_worker (thread=0x7f1bc4030860, obj=) at src/switch_core_session.c:1792
#6 0x00007f1d95faff80 in dummy_worker (opaque=0x7f1bc4030860) at threadproc/unix/thread.c:151
#7 0x00007f1d92e71ea5 in start_thread () from /lib64/libpthread.so.0
#8 0x00007f1d9241a8dd in clone () from /lib64/libc.so.6
Thread 4 (Thread 0x7f1d110d4700 (LWP 80516)):
#0 0x00007f1d92e7539e in pthread_rwlock_wrlock () from /lib64/libpthread.so.0
#1 0x00007f1d95fa9c89 in fspr_thread_rwlock_wrlock (rwlock=) at locks/unix/thread_rwlock.c:97
#2 0x00007f1d95c65645 in switch_thread_rwlock_wrlock (rwlock=) at src/switch_apr.c:253
#3 0x00007f1d95ca3dbc in switch_core_session_write_lock (session=) at src/switch_core_rwlock.c:156
#4 0x00007f1d95c98683 in switch_core_session_thread (thread=, obj=) at src/switch_core_session.c:1747
#5 0x00007f1d95c93d5a in switch_core_session_thread_pool_worker (thread=0x7f1c1002c3e0, obj=) at src/switch_core_session.c:1792
#6 0x00007f1d95faff80 in dummy_worker (opaque=0x7f1c1002c3e0) at threadproc/unix/thread.c:151
#7 0x00007f1d92e71ea5 in start_thread () from /lib64/libpthread.so.0
#8 0x00007f1d9241a8dd in clone () from /lib64/libc.so.6
Thread 3 (Thread 0x7f1d109eb700 (LWP 81381)):
#0 0x00007f1d92e75a35 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x00007f1d95d42e12 in recording_thread (thread=, obj=) at src/switch_ivr_async.c:1329
#2 0x00007f1d95faff80 in dummy_worker (opaque=0x7f1c640bb9f0) at threadproc/unix/thread.c:151
#3 0x00007f1d92e71ea5 in start_thread () from /lib64/libpthread.so.0
#4 0x00007f1d9241a8dd in clone () from /lib64/libc.so.6
Thread 2 (Thread 0x7f1bc9ad3700 (LWP 165508)):
#0 0x00007f1d92e75a35 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x00007f1d95d42e12 in recording_thread (thread=, obj=) at src/switch_ivr_async.c:1329
#2 0x00007f1d95faff80 in dummy_worker (opaque=0x7f1cd01eb590) at threadproc/unix/thread.c:151
#3 0x00007f1d92e71ea5 in start_thread () from /lib64/libpthread.so.0
#4 0x00007f1d9241a8dd in clone () from /lib64/libc.so.6
Thread 1 (Thread 0x7f1d9649f780 (LWP 74493)):
#0 0x00007f1d924119a3 in select () from /lib64/libc.so.6
#1 0x00007f1d95fb15c5 in fspr_sleep (t=) at time/unix/time.c:246
#2 0x00007f1d95ca69d2 in switch_core_runtime_loop (bg=bg@entry=1) at src/switch_core.c:1201
#3 0x0000000000402f48 in main (argc=, argv=) at src/switch.c:1228