Java client fails to connect to Zookeeper and HBase

Question

I wrote a simple HBase client program to perform CRUD operations in my HBase cluster (1 Master and 3 Region Server). The Zookeeper instance is only running in the master server and the quorum includes all the 4 servers. The cluster is running fine and can perform read/write using YCSB client (means there are nothing wrong in the server/zookeeper side).

Now in the eclipse classpath I have added all the HBase libs and hbase-0.94.7.jar (which contains the hbase-default.xml file). I have also added the original hbase-site.xml file from the cluster in the project.

Initially, I ran the client code using the unmodified hbase-default.xml and what I've found that the client is trying to communicate with the localhost for zookeeper instance. And thus ignoring the hbase-site.xml.

Then I've modified the 3 parameters which holds the public IP address of the Master/Zookpeer server and tried again. This time I am getting the below error where the client is continuously trying to connect with the Zookeeper and its other quorum members.

I have all the 4 servers in the Zookeeper quorum and lets say their IP addresses are:

• WWWW // HBase master and Zookeeper Server

• XXXX // HBase RS and Zookeeper Quorum Member

• YYYY // HBase RS and Zookeeper Quorum Member

• ZZZZ // HBase RS and Zookeeper Quorum Member

---

13/06/19 13:06:23 INFO zookeeper.ZooKeeper: Initiating client connection, connectString=W.W.W.W:2181,X.X.X.X:2181,Y.Y.Y.Y:2181,Z.Z.Z.Z:2181 sessionTimeout=180000 watcher=hconnection

13/06/19 13:06:23 INFO zookeeper.RecoverableZooKeeper: The identifier of this process is 5828@Kamal-VAIO

13/06/19 13:06:24 INFO zookeeper.ClientCnxn: Opening socket connection to server W.W.W.W:2181. Will not attempt to authenticate using SASL (unknown error)

13/06/19 13:06:25 WARN zookeeper.ClientCnxn: Session 0x0 for server null, unexpected error, closing socket connection and attempting reconnect

java.net.ConnectException: Connection refused: no further information

---

13/06/19 13:06:25 WARN zookeeper.RecoverableZooKeeper: Possibly transient ZooKeeper exception: org.apache.zookeeper.KeeperException$ConnectionLossException: KeeperErrorCode = ConnectionLoss for /hbase/hbaseid

13/06/19 13:06:25 INFO util.RetryCounter: Sleeping 2000ms before retry #1...

13/06/19 13:06:25 INFO zookeeper.ClientCnxn: Opening socket connection to server X.X.X.X:2181. Will not attempt to authenticate using SASL (unknown error)

13/06/19 13:06:26 WARN zookeeper.ClientCnxn: Session 0x0 for server null, unexpected error, closing socket connection and attempting reconnect

java.net.ConnectException: Connection refused: no further information

---

... and so on

Answer 1

The Problem has been solved.

Solution:

1. Right Click on the Project in Eclipse
2. Go to Properties
3. Select Java Build Path
4. Go to Libraries
5. Click Add Class Folder
6. Add a new folder named conf
7. Press all OK
8. Copy my hbase-site.xml into the conf folder
9. Also add the ip-host lists of my HBase cluster into Win 7 hosts file and save.
10. Run the hbase codes and the client can successfully connect to Zookeeper and HBase master.

NOTE: Step 10 is must, otherwise the client will get the hostnames from the Zookeeper instance and will not able to resolve them.

Many thanks everyone.

Answer 2

Actually the problem is with kafka-client. So in this case, you have to use explicitly kafka-client dependency version 1.0.2 . sometimes other kafka-client versions giving problems. In my case after setting kafka-client version & scope "provided", the error disappeared.

 <dependency>
            <groupId>org.apache.kafka</groupId>
            <artifactId>kafka-clients</artifactId>
            <version>1.0.2</version>
            <scope>provided</scope>
        </dependency>