Hi Sameer, For GoGrid, you will have to configure /etc/hosts with the ip and hostname for master and slaves. If you run hostname and nslookup -sil, you will get the details for your machines. Make sure /etc/hosts has an entry like:
173.1.45.202 173.1.45.202.reverse.gogrid.com 28684_1_85017_358406 Thanks and Regards, Sonal www.meghsoft.com http://in.linkedin.com/in/sonalgoyal On Wed, Jul 28, 2010 at 6:42 AM, Sameer Joshi < [email protected]> wrote: > I installed Java and Hadoop on a GoGrid cloud server using Red Hat > Enterprise Linux Server release 5.1 (Tikanga). Hadoop installed fine and > starts fine, however I get an error (java.lang.NullPointerException at > java.util.concurrent.ConcurrentHashMap) while running the Hadoop wordcount > example. My guess was that this was a localhost or IPv6 issue. > > * I have tested replacing 'localhost' with both the local IP, and server IP > addresses (when out of options) in Hadoop conf > * I have disabled IPv6 both in sysctl.conf and hadoop-env.sh (former > followed by a server restart) > > Any thoughts? > Thank you. > > > The output is given below > > # bin/hadoop jar hadoop-0.20.2-examples.jar wordcount datasets tests/out7 > 10/07/27 05:44:59 INFO input.FileInputFormat: Total input paths to process > : > 1 > 10/07/27 05:44:59 INFO mapred.JobClient: Running job: job_201007270544_0001 > 10/07/27 05:45:00 INFO mapred.JobClient: map 0% reduce 0% > 10/07/27 05:45:12 INFO mapred.JobClient: map 100% reduce 0% > 10/07/27 05:45:17 INFO mapred.JobClient: Task Id : > attempt_201007270544_0001_r_000000_0, Status : FAILED > > Error: java.lang.NullPointerException > at java.util.concurrent.ConcurrentHashMap.get(Unknown Source) > at > > org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.getMapCompletionEvents(ReduceTask.java:2683) > > at > > org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.run(ReduceTask.java:2605) > > > 10/07/27 05:45:24 INFO mapred.JobClient: Task Id : > attempt_201007270544_0001_r_000000_1, Status : FAILED > Error: java.lang.NullPointerException > at java.util.concurrent.ConcurrentHashMap.get(Unknown Source) > at > > org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.getMapCompletionEvents(ReduceTask.java:2683) > > at > > org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.run(ReduceTask.java:2605) > > > 10/07/27 05:45:30 INFO mapred.JobClient: Task Id : > attempt_201007270544_0001_r_000000_2, Status : FAILED > Error: java.lang.NullPointerException > at java.util.concurrent.ConcurrentHashMap.get(Unknown Source) > at > > org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.getMapCompletionEvents(ReduceTask.java:2683) > > at > > org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.run(ReduceTask.java:2605) > > > 10/07/27 05:45:39 INFO mapred.JobClient: Job complete: > job_201007270544_0001 > > 10/07/27 05:45:39 INFO mapred.JobClient: Counters: 12 > 10/07/27 05:45:39 INFO mapred.JobClient: Job Counters > 10/07/27 05:45:39 INFO mapred.JobClient: Launched reduce tasks=4 > 10/07/27 05:45:39 INFO mapred.JobClient: Launched map tasks=1 > 10/07/27 05:45:39 INFO mapred.JobClient: Data-local map tasks=1 > 10/07/27 05:45:39 INFO mapred.JobClient: Failed reduce tasks=1 > 10/07/27 05:45:39 INFO mapred.JobClient: FileSystemCounters > 10/07/27 05:45:39 INFO mapred.JobClient: HDFS_BYTES_READ=15319 > 10/07/27 05:45:39 INFO mapred.JobClient: FILE_BYTES_WRITTEN=12847 > 10/07/27 05:45:39 INFO mapred.JobClient: Map-Reduce Framework > 10/07/27 05:45:39 INFO mapred.JobClient: Combine output records=934 > 10/07/27 05:45:39 INFO mapred.JobClient: Map input records=149 > 10/07/27 05:45:39 INFO mapred.JobClient: Spilled Records=934 > 10/07/27 05:45:39 INFO mapred.JobClient: Map output bytes=25346 > 10/07/27 05:45:39 INFO mapred.JobClient: Combine input records=2541 > 10/07/27 05:45:39 INFO mapred.JobClient: Map output records=2541 > > -- > Dr. Sameer Joshi, Ph.D. > Senior computer scientist, > Serene Software. >
