What is Job Tracker in Hadoop ?
Job Tracker is the daemon ( processing ) service for submitting & tracking Mapreduce jobs
in hadoop. The Job Tracker is the single point of failure of the Map Reduce Service.
If that goes down, all jobs which are running will be halted. In Hadoop Job Tracker performs
following actions.
a)Jobs will be submitted to the JOb Tracker by Client Applications.
b)Job Tracker talks to NameNode to determine the locatoon of the data.
c)JT ( Job Tracker ) locates Task Tracker nodes with available slots at or near the data.
d) JT Submits the work to the chosen task tracker nodes.
e) Than Tast Trackers will be monitored and if they do not submit heartbeat signals often
enough, they are deemed to have failed & the work is scheduled on a different Task Tracker.
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