What is Shuffle Phase

Question

I'm new to map reduce and Hadoop. What is a Shuffle Phase?

Answer 1

Once the first map tasks are completed, the nodes continue to perform several other map tasks and also exchange the intermediate outputs with the reducers as required. This process of moving the intermediate outputs of map tasks to the reducer is referred to as Shuffling.

Answer 2

The process where the intermediate results from the mapper are passed on to the reducer is called shuffle phase.

Comments

Hello @Krishnan. Thanks for your answer. I have another doubt. Is the shuffle phase just the time period where results are passed from mapper to reducer or does something happen in this phase?