We're using CDH 5.0.0 which ships with HIVE 0.12.0. We're running HiveServer2 and connect to it via JDBC. We have zookeeper support enabled. If a connection is made to HS2 and not explicitly closed via JDBC then a connection made to zookeeper is never released. It reaches a point where HS2 hangs and stops executing any new queries. It's easy to replicate with a simple script that connects to HS2 via JDBC and runs a simple query like 'show tables'. At the same time run this on the hive server machine to monitor zookeeper connections: 'while sleep 1; do netstat -anlp | grep 2181 | wc -l; done' .. If you close the connection explicitly the count will go down soon after the program exits.