Hadoop MapReduce

Topics 

• Hadoop MapReduce operational architecture 
• MapReduce general concepts 
• Hadoop MapReduce programming 
• Hadoop MapReduce framework 
• Hadoop MapReduce example: Word Count
• Executing Hadoop MapReduce application 
• Input file and Input format

Hadoop MapReduce Operational Architecture

• Job submitter (client): submit jobs to job tracker 
• One Job Tracker node: send tasks to task trackers and coordinate them 
• Multiple Task Tracker nodes: execute job tasks

Job Execution Flow 

1. Job submitter (client) submits a job to Job Tracker 
2. Job Tracker creates execution plan 
3. Job Tracker sends tasks to Task Trackers 
4. Task Trackers performs tasks and also report progress to Job Tracker via heartbeats 
5. Job Tracker manages “map” and “reduce” phases 
6. Job tracker updates states

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