I've created a patch based on trunk for about MAPREDUCE-4502.
Could someone review it?
I have the a concern that I'm out of the way for merging.
I'm planning to do the action as follows:
1. Updating documents to help reviewers understand how the patch works.
2. Adding benchmarks for evaluation.
This is the my first try with the large patch for Hadoop, so I'd appreciate
if experienced hadoop developers give advice for the contribution.