Leadership election with curator and zoo

Question

I run 3 instances of ZooKeeper and this is config:

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 

I use the example of the leader selection code given here: https://git-wip-us.apache.org/repos/asf?p=curator.git;a=tree;f=curator-examples/src/main/java/leader ; h = 73b547eadb98995c0ccbd06a5b76d0741ffef263; hb = HEAD

The code works fine with TestingServer, but when I change the connection string to: "127.0.0.1:2181,127.0.0.1:2182,127.0.0.1:2183" , I get exceptions:

 [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.<init>(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 

What could be the problem?

Answer 1

I'm doing the same thing. I think this could be due to Zookeeper 3.5.1 ClientCnxn. Despite the fact that I will return to curator 2.6.0, I still see the same stack trace. A GET_CONFIG event type is dispatched without event data.

My stack trace looks like this:

  org.apache.curator.framework.imps.CuratorFrameworkImpl: Background exception was not retry-able or retry gave up
 !  java.lang.NullPointerException: null
 !  at java.io.ByteArrayInputStream. (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∗28)

Answer 2

If Zookeeper 3.5.1 is used, then curator recipes 3.2.1+ fix this problem.