title: Leader election with Curator and Zookeeper
body: <p>I am running 3 instances of ZooKeeper and the config is this:</p>
  
  <pre><code>tickTime=2000
  initLimit=10
  syncLimit=5
  dataDir=/tmp/zookeeper1
  clientPort=2181
  maxClientCnxns=1000
  server.1=127.0.0.1:2888:3888
  server.2=127.0.0.1:2889:3889
  server.3=127.0.0.1:2890:3890
  </code></pre>
  
  <p>I am using the leader election example code given here:
  <a href="https://git-wip-us.apache.org/repos/asf?p=curator.git;a=tree;f=curator-examples/src/main/java/leader;h=73b547eadb98995c0ccbd06a5b76d0741ffef263;hb=HEAD">https://git-wip-us.apache.org/repos/asf?p=curator.git;a=tree;f=curator-examples/src/main/java/leader;h=73b547eadb98995c0ccbd06a5b76d0741ffef263;hb=HEAD</a></p>
  
  <p>The code runs fine with TestingServer but when I change connection string to : <code>"127.0.0.1:2181,127.0.0.1:2182,127.0.0.1:2183"</code>,  I get the exceptions:</p>
  
  <pre><code>[main-SendThread(127.0.0.1:2183)] INFO org.apache.zookeeper.ClientCnxn - Opening socket connection to server 127.0.0.1/127.0.0.1:2183. Will not attempt to authenticate using SASL (unknown error)
  [main-SendThread(127.0.0.1:2183)] INFO org.apache.zookeeper.ClientCnxn - Socket connection established, initiating session, client: /127.0.0.1:56111, server: 127.0.0.1/127.0.0.1:2183
  [main-SendThread(127.0.0.1:2183)] INFO org.apache.zookeeper.ClientCnxn - Session establishment complete on server 127.0.0.1/127.0.0.1:2183, sessionid = 0x3521552283c0000, negotiated timeout = 40000
  [main-EventThread] INFO org.apache.curator.framework.state.ConnectionStateManager - State change: CONNECTED
  [main-SendThread(127.0.0.1:2183)] INFO org.apache.zookeeper.ClientCnxn - Unable to read additional data from server sessionid 0x3521552283c0000, likely server has closed socket, closing socket connection and attempting reconnect
  [main-EventThread] INFO org.apache.curator.framework.imps.EnsembleTracker - New config event received: null
  [main-EventThread] ERROR org.apache.curator.framework.imps.CuratorFrameworkImpl - Background exception was not retry-able or retry gave up
  java.lang.NullPointerException
      at java.io.ByteArrayInputStream.&lt;init&gt;(ByteArrayInputStream.java:106)
      at org.apache.curator.framework.imps.EnsembleTracker.processConfigData(EnsembleTracker.java:163)
      at org.apache.curator.framework.imps.EnsembleTracker.access$200(EnsembleTracker.java:48)
      at org.apache.curator.framework.imps.EnsembleTracker$2.processResult(EnsembleTracker.java:134)
      at org.apache.curator.framework.imps.CuratorFrameworkImpl.sendToBackgroundCallback(CuratorFrameworkImpl.java:829)
      at org.apache.curator.framework.imps.CuratorFrameworkImpl.processBackgroundOperation(CuratorFrameworkImpl.java:611)
      at org.apache.curator.framework.imps.WatcherRemovalFacade.processBackgroundOperation(WatcherRemovalFacade.java:151)
      at org.apache.curator.framework.imps.GetConfigBuilderImpl$2.processResult(GetConfigBuilderImpl.java:210)
      at org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:619)
      at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:528)
  [main-EventThread] INFO org.apache.curator.framework.state.ConnectionStateManager - State change: SUSPENDED
  </code></pre>
  
  <p>What could be the issue?</p>