[root@localhost tmp]# asterisk -rvvv
Asterisk 16.6.1 (debug build 16.6.1), Copyright (C) 1999 - 2018, Digium, Inc. and others.
Created by Mark Spencer <markster@digium.com>
Asterisk comes with ABSOLUTELY NO WARRANTY; type 'core show warranty' for details.
This is free software, with components licensed under the GNU General Public
License version 2 and other licenses; you are welcome to redistribute it under
certain conditions. Type 'core show license' for details.
=========================================================================
Connected to Asterisk 16.6.1 (debug build 16.6.1) currently running on localhost (pid = 6771)
localhost*CLI> 
localhost*CLI> core show locks 

=======================================================================
=== 16.6.1 (debug build 16.6.1)
=== Currently Held Locks
=======================================================================
===
=== <pending> <lock#> (<file>): <lock type> <line num> <function> <lock name> <lock addr> (times locked)
===
=== Thread ID: 0x7fbe7f73d700 LWP:6779 (worker_start         started at [ 1111] threadpool.c worker_thread_start())
=== ---> Waiting for Lock #0 (threadpool.c): MUTEX 364 threadpool_execute pool 0x21b6eb0 (1)
	asterisk __ast_pthread_mutex_lock()
	asterisk __ao2_lock()
	asterisk <unknown>()
	asterisk <unknown>()
	asterisk ast_taskprocessor_push()
	asterisk ast_threadpool_push()
	asterisk <unknown>()
	asterisk <unknown>()
=== -------------------------------------------------------------------
===
=======================================================================

    -- Remote UNIX connection
    -- Remote UNIX connection disconnected
localhost*CLI>