BenchMark工具-JMH介绍
fpcm
10年前
JMH是有OpenJDK开发的基准测试（Benchmark）工具。JMH可以为写基准测试和运行测试提供很好的支持。JMH在Concurrent Benchmarks也提供很好的支持，可以说是多功能测试工具。JMH在2013被公布出来，现在最新版本到1.9。
JMH基本用法:
JMH环境构建
1 使用maven工程，直接在项目中引入相应的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>
2 或者直接用JMH的archetype创建：
mvn archetype:generate \ -DinteractiveMode=false \ -DarchetypeGroupId=org.openjdk.jmh \ -DarchetypeArtifactId=jmh-java-benchmark-archetype \ -DgroupId=com.yao \ -DartifactId=jmh-demo \ -Dversion=1.0
环境搭建好之后然后就可以写相应的测试用例了
Demo如下
public class JMHSample_01_HelloWorld { @Benchmark public void wellHelloThere() { // this method was intentionally left blank. } /* * a) Via command-line: * $ mvn clean install * $ java -jar target/benchmarks.jar JMHSample_01 * * JMH generates self-contained JARs, bundling JMH together with it. * The runtime options for the JMH are available with "-h": * $ java -jar target/benchmarks.jar -h * * b) Via the Java API: * (see the JMH homepage for possible caveats when running from IDE: * http://openjdk.java.net/projects/code-tools/jmh/) */ public static void main(String[] args) throws RunnerException { Options opt = new OptionsBuilder() .include(JMHSample_01_HelloWorld.class.getSimpleName()) .forks(1) .build(); new Runner(opt).run(); }
运行上面的Demo有两种方法：一个是直接打包，然后会在target中生成benchmarks.jar,里面带有main方法，就直接可以运行：java -jar target/benchmarks.jar。运行后的结果如下格式：（运行的结果也写入指定的文件）
Result "wellHelloThere": 3142305096.924 ±(99.9%) 17949665.603 ops/s [Average] (min, avg, max) = (2907217981.526, 3142305096.924, 3226536099.659), stdev = 76000008.112 CI (99.9%): [3124355431.320, 3160254762.527] (assumes normal distribution) # Run complete. Total time: 00:06:42 Benchmark Mode Cnt Score Error Units MyBenchmark.testMethod thrpt 200 3142305096.924 ± 17949665.603 ops/s
同时也支持在IDE中直接运行。
往往在写用例的时候，可以不写main方法，直接在方法上写个Junit的Test注解 ，功能和main相同。
比如netty5中为所有的benchmarks写了一个基类如下：
@Warmup(iterations = AbstractMicrobenchmark.DEFAULT_WARMUP_ITERATIONS) @Measurement(iterations = AbstractMicrobenchmark.DEFAULT_MEASURE_ITERATIONS) @Fork(AbstractMicrobenchmark.DEFAULT_FORKS) @State(Scope.Thread) public class AbstractMicrobenchmark { protected static final int DEFAULT_WARMUP_ITERATIONS = 10; protected static final int DEFAULT_MEASURE_ITERATIONS = 10; protected static final int DEFAULT_FORKS = 2; public static final class HarnessExecutor extends ThreadPoolExecutor { public HarnessExecutor(int maxThreads, String prefix) { super(0, maxThreads, 1L, TimeUnit.DAYS, new SynchronousQueue<Runnable>(), new DefaultThreadFactory(prefix)); System.out.println("Using harness executor"); } } protected static final String[] JVM_ARGS = { "-server", "-dsa", "-da", "-ea:io.netty...", "-Xms768m", "-Xmx768m", "-XX:MaxDirectMemorySize=768m", "-XX:+AggressiveOpts", "-XX:+UseBiasedLocking", "-XX:+UseFastAccessorMethods", "-XX:+UseStringCache", "-XX:+OptimizeStringConcat", "-XX:+HeapDumpOnOutOfMemoryError", "-Dio.netty.noResourceLeakDetection", "-Dharness.executor=CUSTOM", "-Dharness.executor.class=io.netty.microbench.util.AbstractMicrobenchmark$HarnessExecutor" }; static { ResourceLeakDetector.setLevel(ResourceLeakDetector.Level.DISABLED); } @Test public void run() throws Exception { String className = getClass().getSimpleName(); ChainedOptionsBuilder runnerOptions = new OptionsBuilder() .include(".*" + className + ".*") .jvmArgs(JVM_ARGS); if (getWarmupIterations() > 0) { runnerOptions.warmupIterations(getWarmupIterations()); } if (getMeasureIterations() > 0) { runnerOptions.measurementIterations(getMeasureIterations()); } if (getForks() > 0) { runnerOptions.forks(getForks()); } if (getReportDir() != null) { String filePath = getReportDir() + className + ".json"; File file = new File(filePath); if (file.exists()) { file.delete(); } else { file.getParentFile().mkdirs(); file.createNewFile(); } runnerOptions.resultFormat(ResultFormatType.JSON); runnerOptions.result(filePath); } new Runner(runnerOptions.build()).run(); } protected int getWarmupIterations() { return SystemPropertyUtil.getInt("warmupIterations", -1); } protected int getMeasureIterations() { return SystemPropertyUtil.getInt("measureIterations", -1); } protected int getForks() { return SystemPropertyUtil.getInt("forks", -1); } protected String getReportDir() { return SystemPropertyUtil.get("perfReportDir"); } }
我这里仅仅是入门性的介绍，具体的参数和用法本人也不是很熟悉。
具体介绍和用法参照：http://openjdk.java.net/projects/code-tools/jmh/
本人通过官网摘抄的例子，传到github上了：https://github.com/WangErXiao/jmh-demo
END-----------------------------------------------------------------------------------------