JMH 简单入门

<dependency>
    <groupId>org.openjdk.jmh</groupId>
    <artifactId>jmh-core</artifactId>
    <version>1.19</version>
</dependency>
<dependency>
    <groupId>org.openjdk.jmh</groupId>
    <artifactId>jmh-generator-annprocess</artifactId>
    <version>1.19</version>
</dependency>

.
├── pom.xml
└── src
   ├── main
   │  └── java
   │     └── cn
   │        └── coder4j
   │           └── study
   │              └── demo
   │                 └── jmh
   │                    ├── benchmark
   │                    │  └── StringConnectBenchmark.java
   │                    └── runner
   │                       └── StringBuilderRunner.java
   └── test
      └── java
         └── cn
            └── coder4j
               └── study
                  └── demo

/**
 * coder4j.cn
 * Copyright (C) 2013-2018 All Rights Reserved.
 */
package cn.coder4j.study.demo.jmh.runner;

import cn.coder4j.study.demo.jmh.benchmark.StringConnectBenchmark;
import org.openjdk.jmh.annotations.Mode;
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;

/**
 * @author buhao
 * @version StringBuilderRunner.java, v 0.1 2018-12-25 09:53 buhao
 */
public class StringBuilderRunner {

    public static void main( String[] args ) throws RunnerException {
        Options opt = new OptionsBuilder()
                // 导入要测试的类
                .include(StringConnectBenchmark.class.getSimpleName())
                // 预热5轮
                .warmupIterations(5)
                // 度量10轮
                .measurementIterations(10)
                .mode(Mode.Throughput)
                .forks(3)
                .build();

        new Runner(opt).run();


    }

}

/**
 * coder4j.cn
 * Copyright (C) 2013-2018 All Rights Reserved.
 */
package cn.coder4j.study.demo.jmh.benchmark;

import org.openjdk.jmh.annotations.Benchmark;

/**
 * @author buhao
 * @version StringConnectBenchmark.java, v 0.1 2018-12-25 09:29 buhao
 */
public class StringConnectBenchmark {

    /**
     * 字符串拼接之 StringBuilder 基准测试
     */
    @Benchmark
    public void testStringBuilder() {
        print(new StringBuilder().append(1).append(2).append(3).toString());
    }

    /**
     * 字符串拼接之直接相加基准测试
     */
    @Benchmark
    public void testStringAdd() {
        print(new String()+ 1 + 2 + 3);
    }

    /**
     * 字符串拼接之String Concat基准测试
     */
    @Benchmark
    public void testStringConcat() {
        print(new String().concat("1").concat("2").concat("3"));
    }

    /**
     * 字符串拼接之 StringBuffer 基准测试
     */
    @Benchmark
    public void testStringBuffer() {
        print(new StringBuffer().append(1).append(2).append(3).toString());
    }

    /**
     * 字符串拼接之 StringFormat 基准测试
     */
    @Benchmark
    public void testStringFormat(){
        print(String.format("%s%s%s", 1, 2, 3));
    }

    public void print(String str) {

    }
}

# Run progress: 93.33% complete, ETA 00:00:15
# Fork: 3 of 3
objc[12440]: Class JavaLaunchHelper is implemented in both /Library/Java/JavaVirtualMachines/jdk1.8.0_91.jdk/Contents/Home/jre/bin/java (0x106a7d4c0) and /Library/Java/JavaVirtualMachines/jdk1.8.0_91.jdk/Contents/Home/jre/lib/libinstrument.dylib (0x106af74e0). One of the two will be used. Which one is undefined.
# Warmup Iteration   1: 747281.755 ops/s
# Warmup Iteration   2: 924220.081 ops/s
# Warmup Iteration   3: 1129741.585 ops/s
# Warmup Iteration   4: 1135268.541 ops/s
# Warmup Iteration   5: 1062994.936 ops/s
Iteration   1: 1142834.160 ops/s
Iteration   2: 1143207.472 ops/s
Iteration   3: 1178363.827 ops/s
Iteration   4: 1156408.897 ops/s
Iteration   5: 1123123.829 ops/s
Iteration   6: 1086029.992 ops/s
Iteration   7: 1108795.147 ops/s
Iteration   8: 1125522.731 ops/s
Iteration   9: 1120021.744 ops/s
Iteration  10: 1119916.181 ops/s


Result "cn.coder4j.study.demo.jmh.benchmark.StringConnectBenchmark.testStringFormat":
  1132633.183 ±(99.9%) 16252.303 ops/s [Average]
  (min, avg, max) = (1082146.355, 1132633.183, 1182418.648), stdev = 24325.684
  CI (99.9%): [1116380.879, 1148885.486] (assumes normal distribution)


# Run complete. Total time: 00:03:57

Benchmark                                  Mode  Cnt          Score         Error  Units
StringConnectBenchmark.testStringAdd      thrpt   30   63728919.269 ±  906608.141  ops/s
StringConnectBenchmark.testStringBuffer   thrpt   30  112423521.098 ± 1157072.848  ops/s
StringConnectBenchmark.testStringBuilder  thrpt   30  110558976.274 ±  654163.111  ops/s
StringConnectBenchmark.testStringConcat   thrpt   30   44820009.200 ±  524305.660  ops/s
StringConnectBenchmark.testStringFormat   thrpt   30    1132633.183 ±   16252.303  ops/s