Learning Java Benchmarking Harness

This project is used to learn Java benchmarking. The benchmarking tool itself is the Oracle Java Benchmarking Harness which we dont use directly but as Gradle Plugin.

With JMH you can test the performance of Java code. JMH will not just simply execute the test methods but also do things like warm up iterations to prevent wrong results because of the JIT compiler. Results of such an tests will look like this

# Run complete. Total time: 00:00:13

Benchmark                          Mode  Cnt  Score   Error   Units
SimpleBenchmark.myFirstBenchmark  thrpt    3  3,728 ± 9,612  ops/ms

Run

To execute all Tests in the com.codecrafters.jmh package simply run

./gradlew clean jmh

By default all JMH tests must be in the src/jmh/java directory. This will give you the ability to add JMH tests to existing projects without creating an extra project.

How-to

You can add new benchmarks by adding a new method with an @Benchmark annotation (same as adding tests in JUnit). By default the test will use the configuration from the build.gradle file. Of course you can manually change the configuration of every single test by using JMH Annotations.

All possible gradle JMH properties can be found on the gradle plugin documentation. Best way to learn more about the Annotations is by looking into the official sample tests.