This repository contains performance tests for Java using Java Microbenchmark Harness (JMH).

Since my beginning in software development I'm facing a lot of discussions about performance. Sometimes these discussions are quite useful, but often a lot of discussions are only based on assumptions, not facts. Thus, I saw a lot of so-called performance improvements that were not helpful. Most of these "improvements" made the code more complex, less readable, and usually did not lead to a measurable performance improvement. In my opinion, one should measure, not guess. Everything else is not professional.

Thus, I always go through 4 steps when dealing with performance issues: Measure -> Analyse -> Improve -> Measure again. Besides these steps, you also have to make sure that there are no other actions that infer with your tests and make your measurements inaccurate.

I created this repository to

• shorten discussions about performance in Java. Run the tests, look at the results and make a decision.
• have a basis for implementing further performance tests to shorten discussions.

Run the benchmark tests

Command Line

Run all benchmarks:

./gradlew jmh

Build benchmark jar archives:

./gradlw jmhJar

The jar archives are stored in the build/libs directories.

Run the benchmark archives with other options:

java -jar mapping/build/libs/java-performance-mapping-0.0.1-SNAPSHOT-jmh.jar -f 1 -i 2 -r 5 -wi 2 -w 5

For details take a look at the JMH documentation

IntelliJ IDEA

Run configurations are stored in the root directory .run. So IDEA should automatically detect them. You need the https://plugins.jetbrains.com/plugin/7529-jmh-java-microbenchmark-harness plugin installed.