ConcurrentHashMap does not accept null keys, so get() must have been called with null.
Looking briefly, it seems that a map completion event contained a tracker http address without a hostname? That might be enough to help you debug it in your setup; I don't know. S. On 13 October 2011 22:10, Santosh Belda <[email protected]>wrote: > > > Hi, > > I have setup the hadoop on single node and worked fine but when executing > the wordcount example, following error is thornw, Is this any configuration > issue? > > bin/hadoop jar hadoop-examples-0.20.2-cdh3u1.jar wordcount > /user/hduser/testfiles /user/hduser/output > 11/10/14 10:29:53 INFO input.FileInputFormat: Total input paths to process > : > 3 > 11/10/14 10:29:53 WARN snappy.LoadSnappy: Snappy native library is > available > 11/10/14 10:29:53 INFO util.NativeCodeLoader: Loaded the native-hadoop > library > 11/10/14 10:29:53 INFO snappy.LoadSnappy: Snappy native library loaded > 11/10/14 10:29:53 INFO mapred.JobClient: Running job: job_201110141028_0001 > 11/10/14 10:29:54 INFO mapred.JobClient: map 0% reduce 0% > 11/10/14 10:29:59 INFO mapred.JobClient: map 66% reduce 0% > 11/10/14 10:30:01 INFO mapred.JobClient: Task Id : > attempt_201110141028_0001_r_000000_0, Status : FAILED > Error: java.lang.NullPointerException > at > java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:768) > at > > org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.getMapCompletionEvents(ReduceTask.java:2824) > at > > org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.run(ReduceTask.java:2744) > > 11/10/14 10:30:02 INFO mapred.JobClient: map 100% reduce 0% > 11/10/14 10:30:03 INFO mapred.JobClient: Task Id : > attempt_201110141028_0001_r_000000_1, Status : FAILED > Error: java.lang.NullPointerException > at > java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:768) > at > > org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.getMapCompletionEvents(ReduceTask.java:2824) > at > > org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.run(ReduceTask.java:2744) > > 11/10/14 10:30:05 INFO mapred.JobClient: Task Id : > attempt_201110141028_0001_r_000000_2, Status : FAILED > Error: java.lang.NullPointerException > at > java.util.concurrent.ConcurrentHashMap.get(ConcurrentHashMap.java:768) > at > > org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.getMapCompletionEvents(ReduceTask.java:2824) > at > > org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.run(ReduceTask.java:2744) > > 11/10/14 10:30:08 INFO mapred.JobClient: Job complete: > job_201110141028_0001 > 11/10/14 10:30:08 INFO mapred.JobClient: Counters: 18 > 11/10/14 10:30:08 INFO mapred.JobClient: Job Counters > 11/10/14 10:30:08 INFO mapred.JobClient: Launched reduce tasks=4 > 11/10/14 10:30:08 INFO mapred.JobClient: SLOTS_MILLIS_MAPS=9167 > 11/10/14 10:30:08 INFO mapred.JobClient: Total time spent by all > reduces > waiting after reserving slots (ms)=0 > 11/10/14 10:30:08 INFO mapred.JobClient: Total time spent by all maps > waiting after reserving slots (ms)=0 > 11/10/14 10:30:08 INFO mapred.JobClient: Launched map tasks=3 > 11/10/14 10:30:08 INFO mapred.JobClient: Data-local map tasks=3 > 11/10/14 10:30:08 INFO mapred.JobClient: Failed reduce tasks=1 > 11/10/14 10:30:08 INFO mapred.JobClient: SLOTS_MILLIS_REDUCES=3292 > 11/10/14 10:30:08 INFO mapred.JobClient: FileSystemCounters > 11/10/14 10:30:08 INFO mapred.JobClient: FILE_BYTES_READ=740427 > 11/10/14 10:30:08 INFO mapred.JobClient: HDFS_BYTES_READ=2863597 > 11/10/14 10:30:08 INFO mapred.JobClient: FILE_BYTES_WRITTEN=2161157 > 11/10/14 10:30:08 INFO mapred.JobClient: Map-Reduce Framework > 11/10/14 10:30:08 INFO mapred.JobClient: Combine output records=87431 > 11/10/14 10:30:08 INFO mapred.JobClient: Map input records=58570 > 11/10/14 10:30:08 INFO mapred.JobClient: Spilled Records=138742 > 11/10/14 10:30:08 INFO mapred.JobClient: Map output bytes=4774081 > 11/10/14 10:30:08 INFO mapred.JobClient: Combine input records=487561 > 11/10/14 10:30:08 INFO mapred.JobClient: Map output records=487561 > 11/10/14 10:30:08 INFO mapred.JobClient: SPLIT_RAW_BYTES=361 > > -- > View this message in context: > http://old.nabble.com/wordcount-example-throwing-null-pointer-with-ConcurrentHashMap-tp32650178p32650178.html > Sent from the Hadoop core-user mailing list archive at Nabble.com. >
