JMH初体验
作者:互联网
Java 8
JMH 1.19
Eclipse Version: 2021-03 (4.19.0)
---
JMH仓库
https://github.com/openjdk/jmh
https://mvnrepository.com/search?q=jmh
最新版本:1.33 但没用起来,出现了OOM错误(后文解决了此问题)
JMH is a Java harness for building, running, and analysing nano/micro/milli/macro benchmarks written in Java and other languages targetting the JVM.
JMH 是 OpenJDK 团队开发的一款基准测试工具,一般用于代码的性能调优,精度甚至可以达到纳秒级别,适用于 java 以及其他基于 JVM 的语言。
JMH是Java性能测试工具,主要是对工程中一些方法进行一些基准测试,支持的时间单位为:nano / micro / milli / macro
根据参考文档1,添加了下面的测试程序:
package jmh;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.TimeUnit;
import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Level;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
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;
/**
* 使用JMH测试ArrayList、LinkedList的性能——add
* @author ben
* @date 2021-09-23 20:31:23 CST
*/
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.MICROSECONDS)
@State(Scope.Thread)
public class Jmh1 {
// java.lang.OutOfMemoryError: Java heap space
// at java.util.Arrays.copyOf(Arrays.java:3181)
public final static String DATA = "DUMMY DATA";
// public final static String DATA = "D";
// public final static String DATA = "";
private List<String> arrayList;
private List<String> linkedList;
public static int cnt = 0;
@Setup(Level.Iteration)
public void setUp() {
arrayList = new ArrayList<String>();
linkedList = new LinkedList<String>();
}
@Benchmark
public List<String> arrayListAdd() {
cnt++;
try {
this.arrayList.add(DATA);
} catch (OutOfMemoryError e) {
// cnt=157704908, size=157704907
System.out.println("cnt=" + cnt + ", size=" + this.arrayList.size());
throw e;
}
return this.arrayList;
}
@Benchmark
public List<String> linkedListAdd() {
this.linkedList.add(DATA);
return linkedList;
}
public static void main(String[] args) throws RunnerException {
final Options opts = new OptionsBuilder()
.include(Jmh1.class.getSimpleName())
.forks(1)
.measurementIterations(10)
.warmupIterations(10)
.build();
new Runner(opts).run();
}
}
因为是maven项目,pom.xml中添加了下面的依赖包(前面截图中展示了):来自博客园
<!-- JMH -->
<!-- https://mvnrepository.com/artifact/org.openjdk.jmh/jmh-core -->
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-core</artifactId>
<version>1.19</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.openjdk.jmh/jmh-generator-annprocess -->
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-generator-annprocess</artifactId>
<version>1.19</version>
<!-- provided, compile 都可以 -->
<scope>provided</scope>
</dependency>
在Eclipse中启动,出现下面的错误:java.lang.RuntimeException: ERROR: Unable to find the resource: /META-INF/BenchmarkList
根据 参考文档2 解决了问题:Eclipse安装插件 m2e-apt 1.5.3,并做配置
来自博客园
不过,安装插件并配置后,对其它项目的执行有什么影响吗?还需研究下,TODO
上面使用的 JMH版本是 1.19,运行main函数:此时,笔记本的风扇呼呼地响,CPU使用率不用说,直接100%!/心疼电脑
测试结果
# JMH version: 1.19
# VM version: JDK 1.8.0_202, VM 25.202-b08
# VM invoker: D:\Program Files\Java\jdk1.8.0_202\jre\bin\java.exe
# VM options: -Dfile.encoding=UTF-8
# Warmup: 10 iterations, 1 s each
# Measurement: 10 iterations, 1 s each
# Timeout: 10 min per iteration
# Threads: 1 thread, will synchronize iterations
# Benchmark mode: Average time, time/op
# Benchmark: jmh.Jmh1.arrayListAdd
# Run progress: 0.00% complete, ETA 00:00:40
# Fork: 1 of 1
# Warmup Iteration 1: 0.015 us/op
# Warmup Iteration 2: 0.024 us/op
# Warmup Iteration 3: 0.015 us/op
# Warmup Iteration 4: 0.016 us/op
# Warmup Iteration 5: 0.017 us/op
# Warmup Iteration 6: 0.012 us/op
# Warmup Iteration 7: 0.021 us/op
# Warmup Iteration 8: 0.010 us/op
# Warmup Iteration 9: 0.010 us/op
# Warmup Iteration 10: 0.012 us/op
Iteration 1: 0.011 us/op
Iteration 2: 0.020 us/op
Iteration 3: 0.016 us/op
Iteration 4: 0.027 us/op
Iteration 5: 0.020 us/op
Iteration 6: 0.013 us/op
Iteration 7: 0.023 us/op
Iteration 8: 0.017 us/op
Iteration 9: 0.011 us/op
Iteration 10: 0.020 us/op
Result "jmh.Jmh1.arrayListAdd":
0.018 ±(99.9%) 0.008 us/op [Average]
(min, avg, max) = (0.011, 0.018, 0.027), stdev = 0.005
CI (99.9%): [0.010, 0.025] (assumes normal distribution)
# JMH version: 1.19
# VM version: JDK 1.8.0_202, VM 25.202-b08
# VM invoker: D:\Program Files\Java\jdk1.8.0_202\jre\bin\java.exe
# VM options: -Dfile.encoding=UTF-8
# Warmup: 10 iterations, 1 s each
# Measurement: 10 iterations, 1 s each
# Timeout: 10 min per iteration
# Threads: 1 thread, will synchronize iterations
# Benchmark mode: Average time, time/op
# Benchmark: jmh.Jmh1.linkedListAdd
# Run progress: 50.00% complete, ETA 00:00:23
# Fork: 1 of 1
# Warmup Iteration 1: 0.458 us/op
# Warmup Iteration 2: 0.513 us/op
# Warmup Iteration 3: 0.115 us/op
# Warmup Iteration 4: 0.268 us/op
# Warmup Iteration 5: 0.113 us/op
# Warmup Iteration 6: 0.275 us/op
# Warmup Iteration 7: 0.271 us/op
# Warmup Iteration 8: 0.279 us/op
# Warmup Iteration 9: 0.099 us/op
# Warmup Iteration 10: 0.279 us/op
Iteration 1: 0.097 us/op
Iteration 2: 0.269 us/op
Iteration 3: 0.095 us/op
Iteration 4: 0.249 us/op
Iteration 5: 0.095 us/op
Iteration 6: 0.258 us/op
Iteration 7: 0.093 us/op
Iteration 8: 0.256 us/op
Iteration 9: 0.092 us/op
Iteration 10: 0.260 us/op
Result "jmh.Jmh1.linkedListAdd":
0.176 ±(99.9%) 0.131 us/op [Average]
(min, avg, max) = (0.092, 0.176, 0.269), stdev = 0.087
CI (99.9%): [0.046, 0.307] (assumes normal distribution)
# Run complete. Total time: 00:01:18
Benchmark Mode Cnt Score Error Units
Jmh1.arrayListAdd avgt 10 0.018 ± 0.008 us/op
Jmh1.linkedListAdd avgt 10 0.176 ± 0.131 us/op
最后两行展示如下:说明 ArrayList 的add的性能更好。
# Run complete. Total time: 00:01:18
Benchmark Mode Cnt Score Error Units
Jmh1.arrayListAdd avgt 10 0.018 ± 0.008 us/op
Jmh1.linkedListAdd avgt 10 0.176 ± 0.131 us/op
测试中、测试后的JVM进程对比:测试中多了 Jmh1、ForkedMain两个进程
正常测试完毕,接下来,使用最新版的 JMH 1.33进行测试——修改pom.xml文件。
执行测试:出现异常 java.lang.OutOfMemoryError: Java heap space,发生在 this.arrayList.add(DATA) 时。
# Warmup Iteration 1: <failure>
java.lang.OutOfMemoryError: Java heap space
at java.util.Arrays.copyOf(Arrays.java:3181)
at java.util.ArrayList.grow(ArrayList.java:265)
注,上面是 没有捕获异常时的输出。
下面是本文展示的 捕获异常时的输出:第一个warmup居然执行了一亿五千多万次add!然后就发生了一次。
这种情况下,LinkedList的测试是正常的,但ArrayList是没有测试结果的。
最新版本1.33为什么会这样呢?怎么解决?TODO
1.19版本执行时,ArrayList执行了多少次呢?输出每次++后的cnt:才八万多!和1.33的亿级完全没法比啊!难怪1.33会OOM
---210923 2209---
检查@Benchmark注解所在包下的注解,原来还有 @Warmup、@Measurement ,按照参考文档1的说法,这两个也是用来控制测试过程的,可以添加到类和方法上。
在main方法中,使用 OptionsBuilder 来建立Options对象,发现其下有多个 warmup、measurement开头的方法,是否使用这些方法可以来避免OOM呢?可以的。
下面的调用解决了问题:增加了一个 warmupTime、measurementTime 的调用,限定每次 预热、测试 在1秒以内——这样就不会调用add超亿次了吧(我的电脑太好、太快了?)
public static void main(String[] args) throws RunnerException {
final Options opts = new OptionsBuilder()
.include(Jmh1.class.getSimpleName())
.forks(1)
// 预热:使代码的执行经历过了类的早起优化、JVM运行期编译、JIT优化
.warmupIterations(10)
.warmupTime(TimeValue.seconds(1L))
// 真正的度量操作
.measurementIterations(10)
.measurementTime(TimeValue.seconds(1L))
.build();
new Runner(opts).run();
}
更改后的测试结果:使用JMH 1.33成功进行了测试。来自博客园
注,前两行 Warmup、Measurement 后面的 1 s each——正是我们配置的,1.19版本也是这个值,而1.33版本时,这个值是 10 s each——难怪会超亿!
注,也可以使用前面提到的两个注解解决问题。
...
# Warmup: 10 iterations, 1 s each
# Measurement: 10 iterations, 1 s each
# Timeout: 10 min per iteration
...
# Run complete. Total time: 00:01:19
REMEMBER: The numbers below are just data. To gain reusable insights, you need to follow up on
why the numbers are the way they are. Use profilers (see -prof, -lprof), design factorial
experiments, perform baseline and negative tests that provide experimental control, make sure
the benchmarking environment is safe on JVM/OS/HW level, ask for reviews from the domain experts.
Do not assume the numbers tell you what you want them to tell.
Benchmark Mode Cnt Score Error Units
Jmh1.arrayListAdd avgt 10 0.017 ± 0.012 us/op
Jmh1.linkedListAdd avgt 10 0.170 ± 0.126 us/op
1.33版本的日志:
...
# Warmup: 10 iterations, 10 s each
# Measurement: 10 iterations, 10 s each
# Timeout: 10 min per iteration
# Threads: 1 thread, will synchronize iterations
# Benchmark mode: Average time, time/op
# Benchmark: jmh.Jmh1.arrayListAdd
# Run progress: 0.00% complete, ETA 00:06:40
# Fork: 1 of 1
# Warmup Iteration 1: <failure>
java.lang.OutOfMemoryError: Java heap space
at java.util.Arrays.copyOf(Arrays.java:3181)
at java.util.ArrayList.grow(ArrayList.java:265)
...
---210924 0657---
》》》全文完《《《
参考文档
1、《Java高并发编程详解 深入理解并发核心库》
书,by 汪文君
2、Eclipse Benchmark 基准测试 报错:ERROR: Unable to find the resource: /META-INF/BenchmarkList
3、arrays中copyof_Java中:常见的几种内存溢出及解决方案,再遇到后就可以解决了...
4、
标签:10,初体验,Warmup,Iteration,jmh,us,JMH,op 来源: https://www.cnblogs.com/luo630/p/15327760.html