maven依赖

<dependency><groupId>org.openjdk.jmh</groupId><artifactId>jmh-core</artifactId><version>1.36</version></dependency><dependency><groupId>org.openjdk.jmh</groupId><artifactId>jmh-generator-annprocess</artifactId><version>1.36</version></dependency>

简单使用

package com.chauncy.benchmark;import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.State;
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;@State(Scope.Thread)
public class BenchmarkTest1 {double pi = Math.PI;@Benchmarkpublic void measure(){pi++;}public static void main(String[] args) throws RunnerException {Options opt = new OptionsBuilder().include(BenchmarkTest1.class.getSimpleName()).forks(1).build();new Runner(opt).run();}
}

执行多个函数

package com.chauncy.benchmark;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.security.SecureRandom;
import java.util.Arrays;
import java.util.concurrent.TimeUnit;@State(Scope.Benchmark)
@BenchmarkMode(Mode.All)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@Warmup(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS, batchSize = 1)
@Measurement(iterations = 5, time = 1, timeUnit = TimeUnit.SECONDS, batchSize = 1)
@Fork(5)
public class BenchmarkTest2 {private static final int COUNT = 1 ^ 21;private byte[] sorted;private byte[] unsorted;@Setuppublic void setup() {sorted = new byte[COUNT];unsorted = new byte[COUNT];SecureRandom random = new SecureRandom();random.nextBytes(sorted);random.nextBytes(unsorted);Arrays.sort(sorted);}@Benchmark@OperationsPerInvocation(COUNT)public void sorted(Blackhole bh1, Blackhole bh2) {for (byte b : sorted) {if (b > 0) {bh1.consume(b);} else {bh2.consume(b);}}}@Benchmark@OperationsPerInvocation(COUNT)public void unsorted(Blackhole bh1, Blackhole bh2) {for (byte b : unsorted) {if (b > 0) {bh1.consume(b);} else {bh2.consume(b);}}}public static void main(String[] args) throws RunnerException {Options opt = new OptionsBuilder().include(".*" + BenchmarkTest2.class.getSimpleName() + ".*").forks(1).build();new Runner(opt).run();}
}

@BenchmarkMode(Mode.AverageTime) 运行模式

@BenchmarkMode(Mode.Throughput) 吞吐量模式 获取单位时间内的操作数量
@BenchmarkMode(Mode.AverageTime) 平均时间模式 获取每次操作的平均时间
@BenchmarkMode(Mode.SampleTime) 函数运行时间采样模式
@BenchmarkMode(Mode.SingleShotTime)  单次操作时间
@BenchmarkMode(Mode.All) 采用所有的模式

@OutputTimeUnit(TimeUnit.NANOSECONDS) 报告结果时间单位

@Warmup(iterations = 5,time = 1,timeUnit = TimeUnit.SECONDS) 预热参数

iterations 预热的迭代次数
time预热时间
timeUnit 预热时间单位
batchSize 每个基准方法调用次数

@Measurement(iterations = 5,time = 1,timeUnit = TimeUnit.SECONDS,batchSize = 1) 与预热参数类似

@Fork(5) 整体测试次数

@State(Scope.Benchmark) 配置对象作用域

Scope.Benchmark 基准状态范围
Scope.Group 组状态范围
Scope.Thread 线程状态范围

@OperationsPerInvocation(COUNT) 允许与基准进行多个操作的通信