The problem got fixed by using ip-address in all hadoop configuration files and also in /etc/hosts file.
Anyway, thanks Ted. To partially answer your question - line ReduceTask.java:2683 is 'List<MapOutputLocation> loc = mapLocations.get(host);' From: Ted Yu [mailto:[email protected]] Sent: Sunday, July 18, 2010 6:11 PM To: [email protected] Subject: Re: Error: java.lang.NullPointerException at java.util.concurrent.ConcurrentHashMap.get Have you looked at https://issues.apache.org/jira/browse/MAPREDUCE-969 ? It points to https://issues.apache.org/jira/browse/HADOOP-4744 See if HADOOP-4744 is contained in the hadoop version you're running. I am reading cdh3b2 source code. Please confirm that ReduceTask.java:2683 is this line: List<MapOutputLocation> loc = mapLocations.get(host); If so, you can print the value of host, or value of URI u which host is derived. Cheers On Fri, Jul 16, 2010 at 9:42 AM, Chinni, Ravi <[email protected]> wrote: Hadoop version: 0.20.2 From: Ted Yu [mailto:[email protected]] Sent: Friday, July 16, 2010 12:34 PM To: [email protected] Subject: Re: Error: java.lang.NullPointerException at java.util.concurrent.ConcurrentHashMap.get What version of hadoop are you using ? On Fri, Jul 16, 2010 at 8:56 AM, Chinni, Ravi <[email protected]> wrote: I am trying to run the terasort example with a small input on a 4 node cluster. I just did the minimal configuration (fs.default.name, master, slaves etc.), but did not do anything specific to terasort. I am getting the following java.lang.NullPointerException on running terasort example: 10/07/16 11:48:29 INFO terasort.TeraSort: starting 10/07/16 11:48:29 INFO mapred.FileInputFormat: Total input paths to process : 1 10/07/16 11:48:29 INFO util.NativeCodeLoader: Loaded the native-hadoop library 10/07/16 11:48:29 INFO zlib.ZlibFactory: Successfully loaded & initialized native-zlib library 10/07/16 11:48:29 INFO compress.CodecPool: Got brand-new compressor Making 1 from 10 records Step size is 10.0 10/07/16 11:48:30 INFO mapred.JobClient: Running job: job_201006251254_0010 10/07/16 11:48:31 INFO mapred.JobClient: map 0% reduce 0% 10/07/16 11:48:38 INFO mapred.JobClient: map 50% reduce 0% 10/07/16 11:48:39 INFO mapred.JobClient: map 100% reduce 0% 10/07/16 11:48:43 INFO mapred.JobClient: Task Id : attempt_201006251254_0010_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.getM apCompletionEvents(ReduceTask.java:2683) at org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.run( ReduceTask.java:2605) 10/07/16 11:48:49 INFO mapred.JobClient: Task Id : attempt_201006251254_0010_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.getM apCompletionEvents(ReduceTask.java:2683) at org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.run( ReduceTask.java:2605) 10/07/16 11:48:57 INFO mapred.JobClient: Task Id : attempt_201006251254_0010_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.getM apCompletionEvents(ReduceTask.java:2683) at org.apache.hadoop.mapred.ReduceTask$ReduceCopier$GetMapEventsThread.run( ReduceTask.java:2605) Also, I got similar error from reduce jobs on running a streaming map-reduce application. In this case also, the map tasks completed successfully. Any pointers are appreciated. Thanks, Ravi Chinni ________________________________________________________________________ _____ ATTENTION: The information contained in this message (including any files transmitted with this message) may contain proprietary, trade secret or other confidential and/or legally privileged information. Any pricing information contained in this message or in any files transmitted with this message is always confidential and cannot be shared with any third parties without prior written approval from Syncsort. This message is intended to be read only by the individual or entity to whom it is addressed or by their designee. If the reader of this message is not the intended recipient, you are on notice that any use, disclosure, copying or distribution of this message, in any form, is strictly prohibited. If you have received this message in error, please immediately notify the sender and/or Syncsort and destroy all copies of this message in your possession, custody or control.
