As far as I remember (we might run into such a issue ~6 months ago), the TaskTracker can cache the hostname of JobTracker. Try to restart a TaskTrackers, to check if it connects correctly. Please let me know, if restart of TT helped.
2013/11/15 kumar y <ykk1...@gmail.com> > > 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 > > >
