Kafka cannot shutdown

[Json Tu <ka...@126.com>]

Hi all,
	We have a kafka cluster with 11 nodes, and we found there are some partition’s replica num is not equal to isr’s num，because our data traffic is small，we think it should isr’s num should equal to replica’s num at last，
but it can not recovery to normal，so we try to shutdown a broker that have follower partition and not catch up with leader.
	before we shutdown the broker，we found the broker’s id is not in zookeeper’s ids children list，so I think it is disconnected to zookeeper again for some network traffic，but the procedure is alive. we have found this phenomenon for several
times, we think it is the zookeeper callback missed, so the zkclient cannot register it again.
	but it is not my point，my point is，we stop the kafka，but it cannot normal exit，because it will stop at kafkacontroller.shutdown() for very very long time，and we cannot exit the broker util we use kill -9.