cpu is 100%

[sterryxue]

Read the FAQ first: https://github.com/edenhill/librdkafka/wiki/FAQ

Description

when i found the cpu of my process is 100%, i use "top -H -p pid" command at my server
8788 root 20 0 1333484 21872 12980 R 99.3 0.6 14134:31 moniter_agent
i user "pstack pid" command
Thread 12 (Thread 0x7f095effd700 (LWP 8788)):
#0 0x00007f0985d0bc02 in pthread_mutex_lock () from /lib64/libpthread.so.0
#1 0x00000000006ae6a9 in mtx_lock (mtx=) at tinycthread.c:136
#2 0x00000000006616c8 in rd_refcnt_get (R=) at rd.h:305
#3 rd_kafka_broker_thread_main (arg=0x2092f48) at rdkafka_broker.c:3070
#4 0x00000000006ae627 in _thrd_wrapper_function (aArg=) at tinycthread.c:624
#5 0x00007f0985d09dc5 in start_thread () from /lib64/libpthread.so.0
#6 0x00007f098437676d in clone () from /lib64/libc.so.6

How to reproduce

Dual current problem at release v_0.11.4

Checklist

IMPORTANT: We will close issues where the checklist has not been completed.

Please provide the following information:

• librdkafka version v_0.11.4

[edenhill]

Instead of removing the checklist, please fill it out instead.

[edenhill]

dup of #1858