Book Image

YARN Essentials

Book Image

YARN Essentials

Overview of this book

Table of Contents (17 chapters)
YARN Essentials
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Free Chapter
1
Need for YARN
9
YARN – Alternative Solutions
Index

YARN scheduling policies


The YARN architecture has pluggable scheduling policies that depend on the application's requirements and the use case defined for the running application. You can find the YARN scheduling configurations in the yarn-site.xml file. Here, you can specify the scheduling system as either FIFO, capacity, or fair scheduling as per the application's needs. You can also find the running application scheduling information in the ResourceManager UI. Many components of the scheduling system are defined briefly there.

As already mentioned, there are three type of scheduling policies that the YARN scheduler follows:

  • FIFO scheduler

  • Capacity scheduler

  • Fair scheduler

The FIFO (First In First Out) scheduler

This is the scheduling policy introduced into the system from Hadoop 1.0. The JobTracker was used to be FIFO scheduling policies. As the name indicates, FIFO means First in First Out, that is, the job submitted first will execute first. The FIFO scheduler policy does not follow any...