FAQ
Hi,

I am working on 8 node Hadoop cluster, and I am trying to execute a simple
streaming Job with the specified configuration.

hadoop jar
/usr/lib/hadoop-0.20/contrib/streaming/hadoop-streaming-0.20.2-cdh3u0.jar
\-D mapred.map.max.tacker.failures=10 \-D mared.map.max.attempts=8 \-D
mapred.skip.attempts.to.start.skipping=8 \-D
mapred.skip.map.max.skip.records=8 \-D mapred.skip.mode.enabled=true \-D
mapred.max.map.failures.percent=5 \-input /user/hdfs/ABC/ \-output
"/user/hdfs/output1/" \-mapper "perl -e 'while (<>) { chomp; print; };
exit;" \-reducer "perl -e 'while (<>) { ~s/LR\>/LR\>\n/g; print ; }; exit;"

I am using cloudera's distribution for hadoop CDH3u0 with hadoop 0.20.2.
The problem in execution of this job is that the job is getting failed
everytime. The job is giving the error:

java.lang.Throwable: Child Error
at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:242)
Caused by: java.io.IOException: Task process exit with nonzero status of 1.
at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:229)

-------
java.lang.Throwable: Child Error
at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:242)
Caused by: java.io.IOException: Task process exit with nonzero status of 1.
at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:229)

STDERR on the datanodes:
Exception in thread "main" java.io.IOException: Exception reading
file:/mnt/hdfs/06/local/taskTracker/hdfs/jobcache/job_201107141446_0001/jobToken
at
org.apache.hadoop.security.Credentials.readTokenStorageFile(Credentials.java:146)
at
org.apache.hadoop.mapreduce.security.TokenCache.loadTokens(TokenCache.java:159)
at org.apache.hadoop.mapred.Child.main(Child.java:107)
Caused by: java.io.FileNotFoundException: File
file:/mnt/hdfs/06/local/taskTracker/hdfs/jobcache/job_201107141446_0001/jobToken
does not exist.

For the cause of the error I have checked the following things and still it
is crashing for which I am unable to understand the reason.

1. All the temp directories are in place
2. Memory is way more than it might be required for job (running a small
job)
3. Permissions verified.
4. Nothing Fancier done in the configuration just usual stuff.

The most weird thing is that job runs successfully sometime and fails most
of the time. Any guidance/Help regarding the issues would be really helpful.
I am working on this error from last 4 days and I am not able to figure out
anything. Please Help!!!

Thanks & Regards,
Atul

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postedJul 16, '11 at 3:46p
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