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https://issues.apache.org/jira/browse/MAPREDUCE-3926?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13218050#comment-13218050
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Mitesh Singh Jat commented on MAPREDUCE-3926:
---------------------------------------------
Hi Amar,
In Hadoop 0.23, in the Job History file, the task tracker information of
unfinished map task is stored in TASK_STARTED and MAP_ATTEMPT_STARTED.
Regards,
Mitesh
> No information of unfinished map task in Job History, if all attempts of
> another map task fail.
> -----------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-3926
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-3926
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: jobtracker
> Affects Versions: 0.20.205.0
> Reporter: Mitesh Singh Jat
> Priority: Minor
>
> No information of unfinished map task in Job History, if all attempts of
> another map task fail.
> For example,
> 1. The first map task's first attempt m_000000_0 was making progress
> 2. The second map task failed 4 times, before completion of first map task
> attempt.
> 3. Hence, a job cleanup task was launched and completed, before completion of
> first map task attempt.
> 4. After job cleanup task, runningMapCache is cleaned
> {noformat}
> completedTask() -> jobComplete() -> garbageCollect() -> this.runningMapCache
> = null;
> |-----> retireMap() -> if (runningMapCache == null) "Running cache
> for maps missing!! Job details are missing."
> {noformat}
> 5. Hence, "Running cache for maps missing!! Job details are missing." error
> comes
> (from retireMap() which is called after jobComplete() ) and no information is
> added further to Job History. Therefore, first map task's information is
> missing from Job History page.
> I have created a sample streaming MR job, to reproduce this issue.
> {code:title=mapper.sh}
> #!/bin/bash
> read line
> if [[ "$line" == "sleep" ]]
> then
> for i in 1 2 3
> do
> echo "Sleeping" >&2
> sleep 5
> done
> exit 0
> else
> echo "Exiting" >&2
> exit -1
> fi
> {code}
> Input file: in1.txt is for long running map task (here first map task)
> {code:title=/user/mitesh/input/in1.txt}
> sleep
> {code}
> Input file: in2.txt is for failing map task (here second map task)
> {code:title=/user/mitesh/input/in2.txt}
> exit
> {code}
> Running the sample streaming MR job.
> {noformat}
> $ hadoop fs -rmr -skipTrash xyz
> $ hadoop jar $HADOOP_INSTALL/hadoop-streaming.jar -Dmapred.map.max.attempts=2
> -Dmapred.min.split.size=7 -Dmapred.map.tasks=2 -mapper "mapper.sh" -file
> mapper.sh -reducer NONE -input /user/mitesh/input/in1.txt -input
> /user/mitesh/input/in2.txt -output xyz
> {noformat}
> Job History web UI
> {noformat}
> Hadoop Job job_201201310454_542302 on History Viewer
> User: mitesh
> JobName: streamjob7439640883203077520.jar
> JobConf: hdfs://nn:port/user/mitesh/.staging/job_201201310454_542302/job.xml
> Job-ACLs:
> mapreduce.job.acl-view-job: No users are allowed
> mapreduce.job.acl-modify-job: No users are allowed
> Submitted At: 27-Feb-2012 12:56:02
> Launched At: 27-Feb-2012 12:56:11 (8sec)
> Finished At: 27-Feb-2012 12:56:31 (20sec)
> Status: FAILED
> Failure Info: # of failed Map Tasks exceeded allowed limit. FailedCount: 1.
> LastFailedTask: task_201201310454_542302_m_000001
> Analyse This Job
> Kind Total Tasks(successful+failed+killed) Successful tasks Failed
> tasks Killed tasks Start Time Finish Time
> Setup 1 1 0 0 27-Feb-2012 12:56:12
> 27-Feb-2012 12:56:16 (4sec)
> Map 2 0 2 0 27-Feb-2012 12:56:16 27-Feb-2012
> 12:56:26 (10sec)
> Reduce 0 0 0 0
> Cleanup 1 1 0 0 27-Feb-2012 12:56:26
> 27-Feb-2012 12:56:31 (4sec)
> {noformat}
> Above it shows, only 2 failed tasks (belong to second map task).
> Only from JT logs, the task tracker of first map task can be found.
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