Leader election with Curator and Zookeeper

Question

I am running 3 instances of ZooKeeper and the config is this:

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 am using the leader election example 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 runs fine with TestingServer but when I change connection string to : "127.0.0.1:2181,127.0.0.1:2182,127.0.0.1:2183", I get the 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 issue?

I was using Curator Framework version 3.0.0. I got it working with version 2.9.1. Not sure what the issue is.. — Kunal P.Bharati
If you would, please post this as a bug at issues.apache.org/jira/browse/CURATOR - it looks like it might be a new issue with 3.0.0 — Randgalt
@Randgalt, Thanks. Done here: issues.apache.org/jira/browse/CURATOR-285 — Kunal P.Bharati

Guest Guest · Accepted Answer · 2016-01-06T19:25:53

I am hitting the same issue. I think it might be related to the Zookeeper 3.5.1 ClientCnxn. Even though I return back to curator 2.6.0, I still see the same stack trace. A GET_CONFIG event type is sent without the 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:528)

Leader election with Curator and Zookeeper

2 Answers