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MapReduce >> mail # user >> org.apache.hadoop.mapred.TaskTracker: Caught exception: java.net.UnknownHostException: Invalid host name:


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org.apache.hadoop.mapred.TaskTracker: Caught exception: java.net.UnknownHostException: Invalid host name:
Hi,

we changed the jobtracker name recently in our production and populated the
same value in conf files across all our worker nodes.

couple of tasktrackers ( atleast from what we saw ) are started filling  up
with the below log messages. It works when  i manual do nslookup ,dig for
the jobtracker name.

My question is

1) if it resolved the jobtracker dns name to ip , will it cache that info
in jvm or will it retry everytime ?

2) I have read something on hadoop doing reverse lookup and might run it
these kind of issues if something is not right, any suggestions on what i
can look for ?

Any help is much appreciated. Thanks in advance !!!

 ERROR org.apache.hadoop.mapred.TaskTracker: Caught exception:
java.net.UnknownHostException: Invalid host name: local host is: (unknown);
destination host is: "jobtracker.xxx.xxxx":8021;
java.net.UnknownHostException; For more details see:
http://wiki.apache.org/hadoop/UnknownHost
    at sun.reflect.GeneratedConstructorAccessor5.newInstance(Unknown Source)
    at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
    at org.apache.hadoop.net.NetUtils.wrapWithMessage(NetUtils.java:782)
    at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:741)
    at org.apache.hadoop.ipc.Client$Connection.<init>(Client.java:286)
    at org.apache.hadoop.ipc.Client.getConnection(Client.java:1280)
    at org.apache.hadoop.ipc.Client.call(Client.java:1208)
    at
org.apache.hadoop.ipc.WritableRpcEngine$Invoker.invoke(WritableRpcEngine.java:225)
    at org.apache.hadoop.mapred.$Proxy9.getBuildVersion(Unknown Source)
    at
org.apache.hadoop.mapred.TaskTracker.offerService(TaskTracker.java:1956)
    at org.apache.hadoop.mapred.TaskTracker.run(TaskTracker.java:2872)
    at org.apache.hadoop.mapred.TaskTracker.main(TaskTracker.java:4119)
Caused by: java.net.UnknownHostException
    ... 8 more
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB