How to use benchmarks to evaluate the performance of Java functions?

A way to benchmark the performance of Java functions is to use the Java Microbenchmark Suite (JMH). Specific steps include: Adding JMH dependencies to the project. Create a new Java class annotated with @State to represent the benchmark method. Write the benchmark method in the class and annotate it with @Benchmark. Run the benchmark using the JMH command line tool.

Using benchmarks to evaluate Java function performance

Introduction

Benchmarks are An important way to evaluate the performance of your code. By running benchmarks, you can compare the execution times of different code implementations to make informed optimization decisions. This article explains how to benchmark Java functions using JMH (Java Microbenchmark Suite).

Benchmarking with JMH

JMH is a popular benchmarking library for Java. It provides annotations and APIs to easily write and run benchmarks.

To use JMH for benchmarking, perform the following steps:

1. Add JMH dependencies: In the pom.xml file, add the following dependencies:

<dependency>
  <groupId>org.openjdk.jmh</groupId>
  <artifactId>jmh-core</artifactId>
  <version>1.33</version>
</dependency>

2. Write a benchmark class: Create a new Java class and annotate the class with @State to indicate that it contains the benchmark method . For example:

@State(Scope.Benchmark)
public class MyBenchmark {

  // 初始化测试数据
  @Setup
  public void setup() {
    // ...
  }

  // 基准测试方法
  @Benchmark
  public void myFunction() {
    // ...
  }
}

3. Run the benchmark test: Use the JMH command line tool to run the benchmark test:

jmh MyBenchmark

Practical case

Consider a Java function myFunction that adds a list of integers. Here is a benchmark class to benchmark this function:

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Scope;

import java.util.List;
import java.util.stream.IntStream;

@State(Scope.Benchmark)
public class MyBenchmark {

  // 测试数据
  private List<Integer> numbers;

  @Setup
  public void setup() {
    numbers = IntStream.rangeClosed(0, 1000000).boxed().toList();
  }

  @Benchmark
  public int myFunction() {
    int sum = 0;
    for (int number : numbers) {
      sum += number;
    }
    return sum;
  }
}

After running the benchmark, you will get performance metrics such as average execution time, standard deviation, and throughput. These metrics can help you analyze your code's performance and identify areas for improvement.

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