Re: Hadoop and Fedora Core 6 Adventure, Need Help ASAP

[hadoop hadoop-chetan <ha...@gmail.com>]

Hello Folks

   I somebody has successfully installed Hadoop on FC 6, Please Help
!!!!!!!!!!!

   Just bootstrapping into the Haddop madness and was attempting to install
hadoop on Fedora Core 6.
   Tried all sorts of things but couldn't get past this error which is not
starting the reduce tasks

2008-07-24 13:04:06,642 INFO org.apache.hadoop.mapred.TaskInProgress: Error
from task_200807241301_0001_r_000000_0: java.lang.NullPointerException
        at java.util.Hashtable.get(Hashtable.java:334)
        at
org.apache.hadoop.mapred.ReduceTask$ReduceCopier.fetchOutputs(ReduceTask.java:1103)
        at org.apache.hadoop.mapred.ReduceTask.run(ReduceTask.java:328)
        at
org.apache.hadoop.mapred.TaskTracker$Child.main(TaskTracker.java:2124)


Before you ask, here are the details:

 1. Running hadoop as a single node cluster
 2. Disabled IPV6
 3. Using Hadoop version */hadoop-0.17.1/*
 4. enabled ssh to access local machine
 5. Master and Slaves are set to localhost
 6. Created simple sample file and loaded into DFS
 7. Encountered error when I was running the sample with the wordcount
example provided with the package
 8. Here is my hadoop-site.xml

 <configuration>

<property>
  <name>hadoop.tmp.dir</name>
  <value>/tmp/hadoop-${user.name}</value>
  <description>A base for other temporary directories.</description>
</property>

<property>
  <name>fs.default.name</name>
  <value>hdfs://localhost:54310</value>
  <description>The name of the default file system.  A URI whose
  scheme and authority determine the FileSystem implementation.  The
  uri's scheme determines the config property (fs.SCHEME.impl) naming
  the FileSystem implementation class.  The uri's authority is used to
  determine the host, port, etc. for a filesystem.</description>
</property>

<property>
  <name>mapred.job.tracker</name>
  <value>localhost:54311</value>
  <description>The host and port that the MapReduce job tracker runs
  at.  If "local", then jobs are run in-process as a single map
  and reduce task.
  </description>
</property>

 <property>
   <name>mapred.map.tasks</name>
   <value>1</value>
   <description>
     define mapred.map tasks to be number of slave hosts
   </description>
  </property>

 <property>
   <name>mapred.reduce.tasks</name>
  <value>1</value>
   <description>
     define mapred.reduce tasks to be number of slave hosts
   </description>
  </property>

<property>
  <name>dfs.replication</name>
  <value>1</value>
  <description>Default block replication.
  The actual number of replications can be specified when the file is
created.
  The default is used if replication is not specified in create time.
  </description>
</property>

<property>
   <name>mapred.child.java.opts</name>
   <value>-Xmx1800m</value>
   <description>Java opts for the task tracker child processes.
   The following symbol, if present, will be interpolated: @taskid@ is
 replaced by current TaskID. Any other occurrences of '@' will go unchanged.
 For example, to enable verbose gc logging to a file named for the taskid in
 /tmp and to set the heap maximum to be a gigabyte, pass a 'value' of:
 -Xmx1024m -verbose:gc -Xloggc:/tmp/@taskid@.gc
   </description>
</property>


</configuration>