JMH-Sample - JMHSample_01_HelloWorld - 《刻意练习系列》

由于原文翻译过来还是很难看懂，并且夹杂了很多不重要的信息。所以我在「」中进行了总结，「」中的内容可以不看，也可以只看「」中的内容。
package org.openjdk.jmh.samples;
import org.openjdk.jmh.annotations.Benchmark;
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;
public class JMHSample_01_HelloWorld {
    /*
     * This is our first benchmark method.
     * 这是我们第一个基准测试方法。
     *
     * JMH works as follows: users annotate the methods with @Benchmark, and
     * then JMH produces the generated code to run this particular benchmark as
     * reliably as possible. In general one might think about @Benchmark methods
     * as the benchmark "payload", the things we want to measure. The
     * surrounding infrastructure is provided by the harness itself.
     * JMH会做如下工作：用户使用@Benchmark注解方法，然后JMH会生成代码去尽可能可靠地运行
     * 这个指定的基准测试。一般来说，可以将@Benchmark注解的方法看作基准测试的“负载”，
     * 即我们想度量的东西。「我们想度量的东西叫做“负载”，在方法上加上@Benchmark注解
     * 可以使其变成一个“负载”。」周边的基础设施将由用具自身提供。
     *
     * Read the Javadoc for @Benchmark annotation for complete semantics and
     * restrictions. At this point we only note that the methods names are
     * non-essential, and it only matters that the methods are marked with
     * @Benchmark. You can have multiple benchmark methods within the same
     * class.
     * 请阅读@Benchmark注解的Javadoc获取完整的语义与限制。在这里我们注意到方法名没有
     * 特殊要求，只需在方法上标记@Benchmark注解。在同一个类中可以有多个基准测试方法。
     *
     * Note: if the benchmark method never finishes, then JMH run never finishes
     * as well. If you throw an exception from the method body the JMH run ends
     * abruptly for this benchmark and JMH will run the next benchmark down the
     * list.
     * 如果基准测试方法永不结束，那么JMH运行也永远不会结束。如果你从方法体中抛出一个
     * 异常，那么基准测试的运行将突然终止，并且JMH将运行列表中的下一个基准测试。
     * 「如果被测方法抛出异常，则该项测试结束，继续进行下一项测试。」
     *
     * Although this benchmark measures "nothing" it is a good showcase for the
     * overheads the infrastructure bear on the code you measure in the method.
     * There are no magical infrastructures which incur no overhead, and it is
     * important to know what are the infra overheads you are dealing with. You
     * might find this thought unfolded in future examples by having the
     * "baseline" measurements to compare against.
     * 尽管这个基准测试度量什么也没做，但是它很好地展示了基础设施对方法中你度量的代码所承担的开销。
     * 不存在不会产生开销的魔法般的基础设施，了解你要处理的基础开销是很重要的。
     * 你可能会发现这个思想体现在之后的例子中，通过用于比较的“基准线”度量值。
     * 「虽然这个被测方法是空的，但是从中可以得到基础设施的方法调用的开销。
     * 这个开销可以用作其他测试的“基准线”。」
     */
    @Benchmark
    public void wellHelloThere() {
        // this method was intentionally left blank.
    }
    /*
     * ============================== HOW TO RUN THIS TEST: ====================================
     *
     * You are expected to see the run with large number of iterations, and
     * very large throughput numbers. You can see that as the estimate of the
     * harness overheads per method call. In most of our measurements, it is
     * down to several cycles per call.
     * 你将看到大量的迭代和非常大的吞吐量。
     * 你可以将其视为每个方法调用的管理开销的估计值。
     * 在我们大多数测量中，每次调用可以归结为几个周期。
     *
     * 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();
    }
}