Book Image

YARN Essentials

Book Image

YARN Essentials

Overview of this book

Table of Contents (17 chapters)
YARN Essentials
About the Authors
About the Reviewers
Free Chapter
Need for YARN
YARN – Alternative Solutions

YARN scheduler policies

As explained in the previous section, the ResourceManager acts as a pluggable global scheduler that manages and controls all the containers (resources). There are three different policies that can be applied over the scheduler, as per requirements and resource availability. They are as follows:

  • The FIFO scheduler

  • The Fair scheduler

  • The Capacity scheduler

The FIFO (First In First Out) scheduler

FIFO means First In First Out. As the name indicates, the job submitted first will get priority to execute; in other words, the job runs in the order of submission. FIFO is a queue-based scheduler. It is a very simple approach to scheduling and it does not guarantee performance efficiency, as each job would use a whole cluster for execution. So other jobs may keep waiting to finish their execution, although a shared cluster has a great capability to offer more-than-enough resources to many users.

The fair scheduler

Fair scheduling is the policy of scheduling that assigns resources...