[ZOOKEEPER-1875] NullPointerException in ClientCnxn$EventThread.processEvent

• Type: Bug
• Status: Reopened
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 3.4.5, 3.4.10
• Component/s: java client
• Labels: pull-request-available
• Assignee: Mohammad Arshad
• Reporter: Jerry He
• Created: 03/Feb/14 04:06
• Updated: 15/Jun/23 21:09

Description

We've been seeing NullPointerException while working on HBase:

14/01/30 22:15:25 INFO zookeeper.ZooKeeper: Client environment:user.dir=/home/biadmin/hbase-trunk
14/01/30 22:15:25 INFO zookeeper.ZooKeeper: Initiating client connection, connectString=hdtest009:2181 sessionTimeout=90000 watcher=null
14/01/30 22:15:25 INFO zookeeper.ClientCnxn: Opening socket connection to server hdtest009/9.30.194.18:2181. Will not attempt to authenticate using SASL (Unable to locate a login configuration)
14/01/30 22:15:25 INFO zookeeper.ClientCnxn: Socket connection established to hdtest009/9.30.194.18:2181, initiating session
14/01/30 22:15:25 INFO zookeeper.ClientCnxn: Session establishment complete on server hdtest009/9.30.194.18:2181, sessionid = 0x143986213e67e48, negotiated timeout = 60000
14/01/30 22:15:25 ERROR zookeeper.ClientCnxn: Error while calling watcher
java.lang.NullPointerException
        at org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:519)
        at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:495)

The reason is the watcher is null in this part of the code:

       private void processEvent(Object event) {
          try {
              if (event instanceof WatcherSetEventPair) {
                  // each watcher will process the event
                  WatcherSetEventPair pair = (WatcherSetEventPair) event;
                  for (Watcher watcher : pair.watchers) {
                      try {
                          watcher.process(pair.event);
                      } catch (Throwable t) {
                          LOG.error("Error while calling watcher ", t);
                      }
                  }

Issue Links

• relates to: NIFI-8394 Fix NPE error when NiFi connects to external zookeeper insecurely
• links to: GitHub Pull Request #1855