Hadoop: TaskTracker shuts down immediately after start-all.sh

Question

I am running Hadoop 1.0.1 on Ubuntu 11.10.

./bin/start-all.sh

command does not prompt any errors but the TaskTracker fails to start with the following error in the tasktracker.log file:

ERROR org.apache.hadoop.mapred.TaskTracker: Can not start task tracker because java.util.ConcurrentModificationException

at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
at java.util.AbstractList$Itr.next(AbstractList.java:343)
at org.apache.hadoop.mapred.TaskTracker$LocalStorage.checkDirs(TaskTracker.java:211)
at org.apache.hadoop.mapred.TaskTracker.<init>(TaskTracker.java:1447)
at org.apache.hadoop.mapred.TaskTracker.main(TaskTracker.java:3716)

How do I resolve this ?

Answer 1

Try first starting dfs by start-dfs.sh then MapReduce by start-mapred.sh Let's see which process actually causes the error.

Answer 2

Look at this answer: https://stackoverflow.com/a/6280989