Thursday, June 11, 2015


9:41 AM - By ajay desai 0

MapReduce component of hadoop is used for data processing. All the data analysis jobs are done by the MapReduce which is implemented in Java.

                               HIGH LEVEL MAP REDUCE ARCHITECTURE

The High level architecture of MapReduce given above consists of following components:-

1) Job Tracker

2) Task Tracker

                                 1) Job Tracker

This component is present in the name node. The job treats each and every request sent by a client as a Data Analysis Job. The job tracker splits this job into no: of tasks and assigns each and every task to a task tracker present on its respective data node.

                              2) Task Tracker

The task tracker works on the task assigned to it by the job tracker and every task tracker sends an acknowledgement about its task status to the job tracker at regular intervals of time i.e. after every 10 mins. This process of sending acknowledgement is called Heart Beat mechanism.

If the job tracker does not receive an acknowledgement from a task tracker, then the name node will mark that data node as dead and the job tracker will assign the same task to  some other task tracker present on an idle data node. this type of task execution is called as Speculative execution of Hadoop.
Because of this speculative execution, the client does not experience any delay in getting response from the Hadoop environment.

About the Author

I am Azeheruddin Khan having more than 6 year experience in c#, and ms sql.My work comprise of medium and enterprise level projects using and other Microsoft .net technologies. Please feel free to contact me for any queries via posting comments on my blog,i will try to reply as early as possible. Follow me @fresher2programmer
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