java - jmh中的@Group和@GroupThreads指的是什么？

Question

我一直在研究 jmh 实现“多线程”基准测试的方式。据我了解，注释 @Group("Identifier") 和 @GroupThreads(thread_number) 允许并行运行同一组内的基准测试。

@Benchmark
@Group("parallel")
@GroupThreads(1)
public void benchmark_1() {
    while(true) {}
}

@Benchmark
@Group("parallel")
@GroupThreads(1)
public void benchmark_2() {
    while(true) {}
}

使用 CPU 监视器，我发现两个 CPU 已被完全使用。我想知道运行者如何解释这些注释。

Answer 1

您尝试过阅读 Javadocs 吗？那些没有回答问题吗？

例如@Group 说:

 * <p>Multiple {@link Benchmark} methods can be bound in the execution group
 * to produce the asymmetric benchmark. Each execution group contains of one
 * or more threads. Each thread within a particular execution group executes
 * one of {@link Group}-annotated {@link Benchmark} methods. The number of
 * threads executing a particular {@link Benchmark} defaults to a single thread,
 * and can be overridden by {@link GroupThreads}.</p>
 *
 * <p>Multiple copies of an execution group may participate in the run, and
 * the number of groups depends on the number of worker threads requested.
 * JMH will take the requested number of worker threads, round it up to execution
 * group size, and then distribute the threads among the (multiple) groups.
 * Among other things, this guarantees fully-populated execution groups.</p>

 * <p>For example, running {@link Group} with two {@link Benchmark} methods,
 * each having {@link GroupThreads}(4), will run 8*N threads, where N is an
 * integer.</p>

因此，@Group 产生了一个非对称基准，@GroupThreads 控制线程在组内的分布(-tg ... 在CLI 配音)。 @Threads 表示总共要运行多少个线程(-t ... 在 CLI 中称为它)。