According to zookeeper code, when you try to create a client handle to zookeeper, it resolves each of the hosts in the zookeeper connection string. If any of these fail, it throws an exception. If you use a zookeeper based producer, it tries to create a ZkClient handle which in turn tries to create a ZooKeeper handle. Since the ZooKeeper handle has to resolve every host on startup, you have to make sure that is possible.
Thanks, Neha On Tue, May 21, 2013 at 11:09 AM, Jason Rosenberg <j...@squareup.com> wrote: > Hi, > > I am seeing an unexpected situation. My producers use a zkconnection > string to connect to kafka (this is still 0.7.2). If one of the zk hosts > is taken down and removed from dns, it causes an UnknownHostException, and > the producer can't initialize. I expect this is different than the less > severe case where one of the zk's is not responding, but the host still > exists in dns, etc. We are in the process or moving some of our zk > cluster, but I had hoped that it would be ok to do in stages....e.g. as > long as most of the zk's are available in a client's connection string, it > should be ok for it proceed, without having to proactively update and > restart each client with the new zk connect string. > > However, this appears not to be the case (see exception below). Is this > expected? > > org.I0Itec.zkclient.exception.ZkException: Unable to connect to <redacted> > at org.I0Itec.zkclient.ZkConnection.connect(ZkConnection.java:66) > at org.I0Itec.zkclient.ZkClient.connect(ZkClient.java:872) > at org.I0Itec.zkclient.ZkClient.<init>(ZkClient.java:98) > at org.I0Itec.zkclient.ZkClient.<init>(ZkClient.java:84) > at > kafka.producer.ZKBrokerPartitionInfo.<init>(ZKBrokerPartitionInfo.scala:62) > at kafka.producer.Producer.<init>(Producer.scala:47) > at kafka.javaapi.producer.Producer.<init>(Producer.scala:33) > at kafka.javaapi.producer.Producer.<init>(Producer.scala:40) > ...... > Caused by: java.net.UnknownHostException: <redacted> > at java.net.Inet4AddressImpl.lookupAllHostAddr(Native Method) > at java.net.InetAddress$1.lookupAllHostAddr(InetAddress.java:850) > at > java.net.InetAddress.getAddressFromNameService(InetAddress.java:1201) > at java.net.InetAddress.getAllByName0(InetAddress.java:1154) > at java.net.InetAddress.getAllByName(InetAddress.java:1084) > at java.net.InetAddress.getAllByName(InetAddress.java:1020) > at org.apache.zookeeper.ClientCnxn.<init>(ClientCnxn.java:382) > at org.apache.zookeeper.ClientCnxn.<init>(ClientCnxn.java:327) > at org.apache.zookeeper.ZooKeeper.<init>(ZooKeeper.java:383) > at org.I0Itec.zkclient.ZkConnection.connect(ZkConnection.java:64) > ... 19 more > > Jason >
