Hadoop MapReduce well explains the pain is writing too much code for simple MapReduce in Java. This organic blog explains how to use MRJob package in Python to write and execute Movie ratings.

After install the sandbox from the Hortonworks, you can visit the http://localhost:50070 page to find the information about the HDFS cluster. YARN job manager can be access via http://localhost:8088.

Java Futures are the way to support asynchronuous operations. Learn the basics of Java 9 Parallelism before read this post.

The CompletableFuture has been introduced since JDK 8 (2014). This is a abstraction over the `java.util.concurrent. Learn the basics of Java 9 Parallelism before read this post.

Spring property and profile manangement is explained.