You should probably read this before using parallel Streams !

Have you ever wondered “what’s the benefit of using a parallel Stream instead of a sequential Stream in Java” ?

A long time ago, I asked myself this question and at that time I found a nice article with benchmarks. Recently, I tried to get my hands on it again but impossible to find the article. So I did some benchmarks on my own and I will share the results with you.

Context

First some background: the Stream API is available in the JDK since the version 8 released in 2014. So I assume that now most of you will know what is a Stream and how to use it, but I will explain the specifics between a sequential Stream and a parallel one.

To understand the specifics of parallel Streams we need to first understand some basics of Stream in general. Streams are composed of three components: a source, some intermediate operations and a terminal operation.

• The source is the operation generating the data from which a stream will be applied. You can create Streams from any Collection, Array or you can even create one with Stream.of(). There are more ways to create Streams, those were just examples. To create a parallel Stream you have several possibilities: you can directly create the Stream as parallel from a Collection with myCollection.parallelStream() or you can use the intermediate operation .parallel() on an existing Stream to transform it into a parallel Stream;
• Intermediate…