Hope you are doing well
1) You can easily identify the long running map-reduce jobs from the WebUI of Jobhistory server daemon
To start the Jonhistoryserver daemon in a node run the command below :
./sbin/mr-jobhistory-daemon.sh start historyserver
Now To access the history server:
2) Method To Tune Up the Long Running Jobs:
Change the Priority of a Job:
hadoop job -set-priority <job-id> <priority>
There are total 5 different priority level are there. These priority levels are listed below:
From the names of the priority levels, it is quite obvious that highest priority is given to the jobs whose priority level is VERY_HIGH and least priority is given to the jobs whose priority level is VERY_LOW
In the following example, the priority of the long running job is set to VERY_LOW
hadoop job -set-priority job_201403160138_54485 VERY_LOW
I hope this will resolve the query
Pelase let me know if you have any further issue regarding this.
Feel free to contact us in case you have any query.