testing kafka consumer and producer failed on connection - apache-zookeeper

Question

I have been trying to test a kafka installation and using the guide created a producer and consumer. When trying to retrieve a message I get the following error:
WARN Session 0x0 for server null, unexpected error, closing socket connection and
attempting reconnect (org.apache.zookeeper.ClientCnxn)
java.net.ConnectException: Connection refused
at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:739)
at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1146)
[2014-03-04 18:01:20,628] INFO Terminate ZkClient event thread. (org.I0Itec.zkclient.ZkEventThread)
[2014-03-04 18:01:21,315] INFO Opening socket connection to server kafka-test/192.xxxxxx.110:2182 (org.apache.zookeeper.ClientCnxn)
[2014-03-04 18:01:21,418] INFO Session: 0x0 closed (org.apache.zookeeper.ZooKeeper)
Exception in thread "main" org.I0Itec.zkclient.exception.ZkTimeoutException: Unable to connect to zookeeper server within timeout: 6000
at org.I0Itec.zkclient.ZkClient.connect(ZkClient.java:880)
at org.I0Itec.zkclient.ZkClient.<init>(ZkClient.java:98)
at org.I0Itec.zkclient.ZkClient.<init>(ZkClient.java:84)
at kafka.consumer.ZookeeperConsumerConnector.connectZk(ZookeeperConsumerConnector.scala:151)
at kafka.consumer.ZookeeperConsumerConnector.<init>(ZookeeperConsumerConnector.scala:112)
at kafka.consumer.ZookeeperConsumerConnector.<init>(ZookeeperConsumerConnector.scala:123)
at kafka.consumer.Consumer$.create(ConsumerConnector.scala:89)
at kafka.consumer.ConsoleConsumer$.main(ConsoleConsumer.scala:178)
at kafka.consumer.ConsoleConsumer.main(ConsoleConsumer.scala)
[2014-03-04 18:01:21,419] INFO EventThread shut down (org.apache.zookeeper.ClientCnxn)

Answer 1

Kafka
Looks like you're not connecting to Zookeeper correctly. I'm not sure of your setup (multi-machine, VMs, containers) so it's hard to say what's wrong. From the debug output I see the following line hinting at your expected Zookeeper IP:
[2014-03-04 18:01:21,315] INFO Opening socket connection to server kafka-test/192.xxxxxx.110:2182 (org.apache.zookeeper.ClientCnxn)
Kafka looks for Zookeeper at the address specified by the zookeeper.connect configuration property in the $KAFKA_HOME/config/server.properties file. Be sure to edit that before starting Kafka. Also, try giving the actual public IP of your Zookeeper instance, not just 127.0.0.1 as that solves a lot of confusion if you're running in containers. In your case it looks like it would be:
zookeeper.connect=192.xxxxxx.110:2182
Also relevant to the Kafka config if you're running on AWS or operating in a container, don't forget to update the following two configuration properties to make sure clients who connect to Kafka see the correct public IP
advertised.host.name
advertised.port
and Kafka sees the correct internal IP
host.name
port
Zookeeper
Zookeeper has some gotchas when setting it up as well. On your Zookeeper instance, don't forget to edit the server configuration property in the zoo.cfg (usually in /etc/zookeeper/conf) file to point to the correct IP for your Zookeeper instance. In your case probably the following:
server.1=192.xxxxxx.110:2888:3888
Those last two ports (2888 3888) are only needed if you're running a Zookeeper cluster (for followers to connect to the leader and Zookeeper leader election, respectively, so be sure to unblock them on firewallish things if you have multiple Zookeeper servers).

Answer 2

Check your zookeeper connection with telnet command:
telnet 192.xxxxxx.110 2181
You probably get an error, in which case check that the process is running:
ps -ef | grep "zookeeper.properties"
If it's not running, start it by going into kafka home directory:
bin/zookeeper-server-start.sh config/zookeeper.properties &

Answer 3

Something wrong with your Zookeper configuration. Make sure your zookeeper is up and running. The default port it runs on is 2181
Bit more info and some code could be useful I believe.

Answer 4

I hit the same issue and the problem was the max client connections property in zookeeper config.
if you see something like "maxClientCnxns = 20" in the config file in /etc/zookeeper/conf, comment it out and restart zookeeper.

Answer 5

You may also check if the all the connections available have already been exhausted. If you are using an API to connect to ZK, make sure you free up the connection after you're done.

Answer 6

I also meet the problem. When I shutdown the firewall of the zk node, it will work.