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]. Any help? Regards, Paolo [1] 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 [3] 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
