基于JMH对ArrayList和LinkedList插入操作进行性能测试

基于JMH对ArrayList和LinkedList插入操作进行性能测试

​​Java基准测试工具 —— JMH使用指南​​

实验思路

测试以下三种情况，插入性能差距。

• ArrayList
• ArrayList 指定初始化长度
• LinkedList

导入maven依赖

<dependency>
    <groupId>org.openjdk.jmh</groupId>
    <artifactId>jmh-core</artifactId>
    <version>1.23</version>
</dependency>
<dependency>
    <groupId>org.openjdk.jmh</groupId>
    <artifactId>jmh-generator-annprocess</artifactId>
    <version>1.23</version>
</dependency>

测试用代码

import org.openjdk.jmh.annotations.*;
import org.openjdk.jmh.infra.Blackhole;
import org.openjdk.jmh.runner.Runner;
import org.openjdk.jmh.runner.RunnerException;
import org.openjdk.jmh.runner.options.Options;
import org.openjdk.jmh.runner.options.OptionsBuilder;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.TimeUnit;

@BenchmarkMode(Mode.AverageTime)
@Warmup(iterations = 3, time = 1)
@Measurement(iterations = 5, time = 5)
@Threads(4)
@Fork(1)
@State(value = Scope.Benchmark)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
public class ListTest {

    private int size = 500_0000;

    public static void main(String[] args) throws RunnerException {
        Options opt = new OptionsBuilder()
                .include(ListTest.class.getSimpleName())
                .forks(1)
                .build();

        new Runner(opt).run();
    }

    @Benchmark
    public void arrayList(Blackhole blackhole) {
        List<Integer> a = new ArrayList<>();
        for (int i = 0; i < size; i++) {
            a.add(1);
        }
        System.out.println(a.size());
    }

    @Benchmark
    public void arrayList2(Blackhole blackhole) {
        List<Integer> a = new ArrayList<>(size);
        for (int i = 0; i < size; i++) {
            a.add(1);
        }
        System.out.println(a.size());
    }

    @Benchmark
    public void linkedList(Blackhole blackhole) {
        List<Integer> a = new LinkedList<>();
        for (int i = 0; i < size; i++) {
            a.add(1);
        }
        System.out.println(a.size());
    }

}

执行结果

REMEMBER: The numbers below are just data. To gain reusable insights, you need to follow up on
why the numbers are the way they are. Use profilers (see -prof, -lprof), design factorial
experiments, perform baseline and negative tests that provide experimental control, make sure
the benchmarking environment is safe on JVM/OS/HW level, ask for reviews from the domain experts.
Do not assume the numbers tell you what you want them to tell.

Benchmark            Mode  Cnt          Score           Error  Units
ListTest.arrayList   avgt    5   90917367.510 ±  18681506.307  ns/op
ListTest.arrayList2  avgt    5   37638850.686 ±  13428284.589  ns/op
ListTest.linkedList  avgt    5  337937895.252 ± 308730540.843