Java Maven JMH Benchmarking Project

Introduction

This project demonstrates how to use JMH (Java Microbenchmark Harness) to benchmark Java code efficiently. JMH is a Java library developed by the same team that built the JVM and helps in writing reliable microbenchmarks.

Prerequisites

Ensure you have the following installed:

• Java 8+
• Maven 3+

Running the Benchmark

To generate benchmark code and run it, execute:

mvn clean install
java -jar target/benchmarks.jar

Sample Benchmark Output

Benchmark                                 Mode  Cnt   Score    Error   Units
MyBenchmark.allocateLargeArrayOperation  thrpt    5  ≈ 10⁻⁵           ops/ns
MyBenchmark.stringOperation               avgt    5   0.561 ±  0.007   ns/op

Set up sample project

Set up the sample project using Maven Archetype with the command.

mvn archetype:generate \
  -DinteractiveMode=false \
  -DarchetypeGroupId=org.openjdk.jmh \
  -DarchetypeArtifactId=jmh-java-benchmark-archetype \
  -DgroupId=com.example \
  -DartifactId=jmh \ 
  -Dversion=1.0

Understanding JMH Modes

JMH supports multiple benchmarking modes:

• Throughput: Measures operations per second.
• AverageTime: Measures average execution time per operation.
• SampleTime: Measures time for individual operations and samples results.
• SingleShotTime: Measures time for a single operation (used for very fast operations).

You can change the mode by modifying @BenchmarkMode(Mode.AverageTime).