Can you see the logs of tasktracker for full stacktrace? On Thu, Jun 30, 2011 at 12:24 PM, Paolo Castagna < [email protected]> wrote:
> Hi, > I am using Apache Whirr to setup an Hadoop cluster on EC2 using Hadoop > 0.22.0 SNAPSHOTs (nightly) builds from Jenkins. For details, see [1,2]. > (Is there a better place where I can get nightly builds for Hadoop?) > > I have a Reducer which does not emit any (key,value) pairs (it generates > only side effect files). When I run using only one reducer everything seems > fine. If I setup multiple reducers, each one generating different side > effect > files, I get a NullPointerException: > > WARN Exception running child : java.lang.NullPointerException > at org.apache.hadoop.mapred.**TaskLogAppender.flush(** > TaskLogAppender.java:96) > at org.apache.hadoop.mapred.**TaskLog.syncLogs(TaskLog.java:**239) > at org.apache.hadoop.mapred.**Child$4.run(Child.java:225) > at java.security.**AccessController.doPrivileged(**Native Method) > at javax.security.auth.Subject.**doAs(Subject.java:396) > at org.apache.hadoop.security.**UserGroupInformation.doAs(** > UserGroupInformation.java:**1153) > at org.apache.hadoop.mapred.**Child.main(Child.java:217) > > Have you ever seen this exception/stacktrace? > > My driver is here [3] and the reducer is here [4]. > > Regards, > Paolo > > [1] https://github.com/castagna/**tdbloader3/blob/master/hadoop-** > ec2.properties<https://github.com/castagna/tdbloader3/blob/master/hadoop-ec2.properties> > [2] https://builds.apache.org/**view/G-L/view/Hadoop/job/** > Hadoop-22-Build/**lastSuccessfulBuild/artifact/** > hadoop-0.22.0-SNAPSHOT.tar.gz<https://builds.apache.org/view/G-L/view/Hadoop/job/Hadoop-22-Build/lastSuccessfulBuild/artifact/hadoop-0.22.0-SNAPSHOT.tar.gz> > [3] https://github.com/castagna/**tdbloader3/blob/master/src/** > main/java/com/talis/labs/tdb/**tdbloader3/ThirdDriver.java<https://github.com/castagna/tdbloader3/blob/master/src/main/java/com/talis/labs/tdb/tdbloader3/ThirdDriver.java> > [4] https://github.com/castagna/**tdbloader3/blob/master/src/** > main/java/com/talis/labs/tdb/**tdbloader3/ThirdReducer.java<https://github.com/castagna/tdbloader3/blob/master/src/main/java/com/talis/labs/tdb/tdbloader3/ThirdReducer.java> > >
