https://community.cloudera.com/t5/Support-Questions/why-zookeeper-goes-down-when-maximum-client-connection/m-p/166985#M129317 <P>Hi @<A href="https://community.hortonworks.com/users/393/aervits.html">Artem Ervits</A> Thanks for response. I checked /etc/zookeeper/conf/zoo.cfg and after upgradation I found same values as before. So I could not find out the exact problem on looking into the configuration files.</P><P>2017-02-08 00:41:52,616 - WARN [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxn@357] - caught end of stream exception EndOfStreamException: Unable to read additional data from client sessionid 0x15a19e6cf730013, likely client has closed socket at org.apache.zookeeper.server.NIOServerCnxn.doIO(NIOServerCnxn.java:228) at org.apache.zookeeper.server.NIOServerCnxnFactory.run(NIOServerCnxnFactory.java:208) at java.lang.Thread.run(Thread.java:745) 2017-02-08 00:41:52,675 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxn@1007] - Closed socket connection for client /172.17.0.2:34852 which had sessionid 0x15a19e6cf730013 2017-02-08 00:41:54,441 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxnFactory@197] - Accepted socket connection from /172.17.0.2:40119 2017-02-08 00:41:54,442 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:ZooKeeperServer@861] - Client attempting to renew session 0x15a19e6cf730013 at /172.17.0.2:40119 2017-02-08 00:41:54,443 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:ZooKeeperServer@617] - Established session 0x15a19e6cf730013 with negotiated timeout 10000 for client /172.17.0.2:40119 2017-02-08 00:42:19,328 - WARN [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxn@357] - caught end of stream exception EndOfStreamException: Unable to read additional data from client sessionid 0x15a19e6cf730013, likely client has closed socket at org.apache.zookeeper.server.NIOServerCnxn.doIO(NIOServerCnxn.java:228) at org.apache.zookeeper.server.NIOServerCnxnFactory.run(NIOServerCnxnFactory.java:208) at java.lang.Thread.run(Thread.java:745) 2017-02-08 00:42:19,329 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxn@1007] - Closed socket connection for client /172.17.0.2:40119 which had sessionid 0x15a19e6cf730013 2017-02-08 00:42:20,004 - INFO [SessionTracker:ZooKeeperServer@347] - Expiring session 0x15a19e6cf730013, timeout of 10000ms exceeded 2017-02-08 00:42:20,005 - INFO [ProcessThread(sid:0 cport:-1)::PrepRequestProcessor@494] - Processed session termination for sessionid: 0x15a19e6cf730013 2017-02-08 00:42:20,477 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxnFactory@197] - Accepted socket connection from /172.17.0.2:40193 2017-02-08 00:42:20,488 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:ZooKeeperServer@861] - Client attempting to renew session 0x15a19e6cf730013 at /172.17.0.2:40193 2017-02-08 00:42:20,489 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:ZooKeeperServer@610] - Invalid session 0x15a19e6cf730013 for client /172.17.0.2:40193, probably expired 2017-02-08 00:42:20,489 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxn@1007] - Closed socket connection for client /172.17.0.2:40193 which had sessionid 0x15a19e6cf730013 2017-02-08 00:42:20,588 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:NIOServerCnxnFactory@197] - Accepted socket connection from /172.17.0.2:40194 2017-02-08 00:42:20,589 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:2181:ZooKeeperServer@868] - Client attempting to establish new session at /172.17.0.2:40194 2017-02-08 00:42:20,626 - INFO [SyncThread:0:ZooKeeperServer@617] - Established session 0x15a19e6cf730015 with negotiated timeout 10000 for client /172.17.0.2:40194</P><P>Above are logs but I could not find any issue from here.</P><P>Please advise .</P> Fri, 10 Feb 2017 04:13:26 GMT amitpanda147 2017-02-10T04:13:26Z