Java Benchmark 基准测试的实例详解

Java Benchmark 基准测试的实例详解

import java.util.Arrays;
import java.util.concurrent.TimeUnit; 

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Threads;
import org.openjdk.jmh.annotations.Warmup;
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; 

@BenchmarkMode(Mode.Throughput)//基准测试类型
@OutputTimeUnit(TimeUnit.SECONDS)//基准测试结果的时间类型
@Warmup(iterations = 3)//预热的迭代次数
@Threads(2)//测试线程数量
@State(Scope.Thread)//该状态为每个线程独享
//度量:iterations进行测试的轮次，time每轮进行的时长，timeUnit时长单位,batchSize批次数量
@Measurement(iterations = 2, time = -1, timeUnit = TimeUnit.SECONDS, batchSize = -1)
public class InstructionsBenchmark{
  static int staticPos = 0;
  //String src = "SELECT a FROM ab       , ee.ff AS f,(SELECT a FROM `schema_bb`.`tbl_bb`,(SELECT a FROM ccc AS c, `dddd`));";
  final byte[] srcBytes = {83, 69, 76, 69, 67, 84, 32, 97, 32, 70, 82, 79, 77, 32, 97, 98, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 32, 44, 32, 101, 101, 46, 102, 102, 32, 65, 83, 32, 102, 44, 40, 83, 69, 76, 69, 67, 84, 32, 97, 32, 70, 82, 79, 77, 32, 96, 115, 99, 104, 101, 109, 97, 95, 98, 98, 96, 46, 96, 116, 98, 108, 95, 98, 98, 96, 44, 40, 83, 69, 76, 69, 67, 84, 32, 97, 32, 70, 82, 79, 77, 32, 99, 99, 99, 32, 65, 83, 32, 99, 44, 32, 96, 100, 100, 100, 100, 96, 41, 41, 59};
  int len = srcBytes.length;
  byte[] array = new byte[8192];
  int memberVariable = 0; 

  //run
  public static void main(String[] args) throws RunnerException {
    Options opt = new OptionsBuilder()
        .include(InstructionsBenchmark.class.getSimpleName())
        .forks(1)
        //   使用之前要安装hsdis
        //-XX:-TieredCompilation 关闭分层优化 -server
        //-XX:+LogCompilation 运行之后项目路径会出现按照测试顺序输出hotspot_pid<PID>.log文件,可以使用JITWatch进行分析,可以根据最后运行的结果的顺序按文件时间找到对应的hotspot_pid<PID>.log文件
        .jvmArgs("-XX:+UnlockDiagnosticVMOptions", "-XX:+LogCompilation", "-XX:+TraceClassLoading", "-XX:+PrintAssembly")
        // .addProfiler(CompilerProfiler.class)  // report JIT compiler profiling via standard MBeans
        // .addProfiler(GCProfiler.class)  // report GC time
        // .addProfiler(StackProfiler.class) // report method stack execution profile
        // .addProfiler(PausesProfiler.class)
        /*
        WinPerfAsmProfiler
        You must install Windows Performance Toolkit. Once installed, locate directory with xperf.exe file
        and either add it to PATH environment variable, or set it to jmh.perfasm.xperf.dir system property.
         */
        //.addProfiler(WinPerfAsmProfiler.class)
        //更多Profiler,请看JMH介绍
        //.output("InstructionsBenchmark.log")//输出信息到文件
        .build();
    new Runner(opt).run();
  } 

  //空循环 对照项
  @Benchmark
  public int emptyLoop() {
    int pos = 0;
    while (pos < len) {
      ++pos;
    }
    return pos;
  } 

  @Benchmark
  public int increment() {
    int pos = 0;
    int result = 0;
    while (pos < len) {
      ++result;
      ++pos;
    }
    return result;
  } 

  @Benchmark
  public int decrement() {
    int pos = 0;
    int result = 0;
    while (pos < len) {
      --result;
      ++pos;
    }
    return result;
  } 

  @Benchmark
  public int ifElse() {
    int pos = 0;
    int result = 0;
    while (pos < len) {
      if (pos == 10) {
        ++result;
        ++pos;
      } else {
        ++pos;
      }
    }
    return result;
  } 

  @Benchmark
  public int ifElse2() {
    int pos = 0;
    int result = 0;
    while (pos < len) {
      if (pos == 10) {
        ++result;
        ++pos;
      } else if (pos == 20) {
        ++result;
        ++pos;
      } else {
        ++pos;
      }
    }
    return result;
  } 

  @Benchmark
  public int ifnotElse() {
    int pos = 0;
    int result = 0;
    while (pos < len) {
      if (pos != 10) {
        ++pos;
      } else {
        ++result;
        ++pos;
      }
    }
    return result;
  } 

  @Benchmark
  public int ifLessthanElse() {
    int pos = 0;
    int result = 0;
    while (pos < len) {
      if (pos < 10) {
        ++pos;
      } else {
        ++result;
        ++pos;
      }
    }
    return result;
  } 

  @Benchmark
  public int ifGreaterthanElse() {
    int pos = 0;
    int result = 0;
    while (pos < len) {
      if (pos > 10) {
        ++pos;
      } else {
        ++result;
        ++pos;
      }
    }
    return result;
  } 

  @Benchmark
  public int readMemberVariable_a_byteArray() {
    int pos = 0;
    int result = 0;
    while (pos < len) {
      result = srcBytes[pos];
      pos++;
    }
    return result;
  } 

}

ops/time：标识每秒钟执行的次数

依赖jar包：

<dependency>
      <groupId>org.openjdk.jmh</groupId>
      <artifactId>jmh-core</artifactId>
      <version>${jmh.version}</version>
    </dependency>
    <dependency>
      <groupId>org.openjdk.jmh</groupId>
      <artifactId>jmh-generator-annprocess</artifactId>
      <version>${jmh.version}</version>
      <scope>provided</scope>
    </dependency>

<build>
    <plugins>
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>exec-maven-plugin</artifactId>
        <executions>
          <execution>
            <id>run-benchmarks</id>
            <phase>integration-test</phase>
            <goals>
              <goal>exec</goal>
            </goals>
            <configuration>
              <classpathScope>test</classpathScope>
              <executable>java</executable>
              <arguments>
                <argument>-classpath</argument>
                <classpath />
                <argument>org.openjdk.jmh.Main</argument>
                <argument>.*</argument>
              </arguments>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>

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