HiveServer2 hangs silently, need to check how many live connections are on HS2, how can this be done ?
I think there is no direct way to do this but you can try to grep some log text.
take a heap dump of hiveserver2 and use object query language ( SELECT toString(s.username) FROM INSTANCEOF org.apache.hive.service.cli.session.HiveSessionImpl s ) to know live sessions at that moment. to run object query language you can use jvisualvm or Eclipse MAT.
By connecting to web ui over port 10002 one could check the number of live sessions on that instance of hiveserver