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)                  //.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;   }  }