In-mapper Combiner Program to Calculate Average

In my previous post I described how we can use in-mapper combiner to make our M/R program more efficient. In the post, we also saw both M/R algorithm for average calculation with/without using in-mapper combiner optimization.

In this post I am posting codes for both the algorithm.

The M/R program to calculate average without in-mapper combiner is given below:

The M/R program to calculate average with in-mapper combiner is given below:


The programs took 56sec and 42sec respectively for execution on my laptop for 10million records. So we can see a 33% improvement in time while using in-mapper combiner program.