Use JMH for micro benchmarking

Use JMH for micro benchmarking

Purpose and introduction

• Sometimes we want to test the execution efficiency of a method, a function, and a class. The most earthly method is to make a time difference:

long timebegin = System.nanoTime();
for(int timei = 0; timei < 10; timei++){
    
    
    do somethings;
}
long timeend = System.nanoTime();
System.out.println("cost time:" + (timeend - timebegin));

• Although this method is convenient and simple, it is rough and inaccurate. Today, we will introduce JMH, a Java microbenchmark test tool, which can accurately give the actual efficiency of this method.

Construction and design ideas

• Import JMH jar package

<dependencies>
    <dependency>
        <groupId>org.openjdk.jmh</groupId>
        <artifactId>jmh-core</artifactId>
        <version>1.19</version>
    </dependency>
    <dependency>
        <groupId>org.openjdk.jmh</groupId>
        <artifactId>jmh-generator-annprocess</artifactId>
        <version>1.19</version>
        <scope>provided</scope>
    </dependency>
</dependencies>

• Main note

@BenchmarkMode
@OutputTimeUnit
@Iteration
@WarmUp
@State
@Fork
@Meansurement
@Setup
@TearDown
@Benchmark
@Param

Actual use case

• Explanation: I want to test the efficiency of the twelve sorting methods I wrote , so I respectively are as follows:
• Main method

@OutputTimeUnit(TimeUnit.NANOSECONDS)
public class InnerSortRealizeTimeTest {
    
    
    @Test
    public void sortTimeTest() throws RunnerException {
    
    

        Options options = new OptionsBuilder().
                include("SortTest")//此处是模糊匹配
                .warmupIterations(2)//预热2轮
                .measurementIterations(2)//实际2轮
                .forks(2)//预热2轮+实际2轮算一组，这是循环2组
                .build();
        new Runner(options).run();
    }
}

• Add to all methods to be tested

@Benchmark
@BenchmarkMode(Mode.Throughput)

• Test Results

Benchmark                                                                                                                          Mode  Cnt      Score       Error  Units
normalSortTest.BucketSortTest.TestInnerSortRealize         thrpt    4   5235.110 ±  2652.157  ops/s
normalSortTest.CountSortTest.TestInnerSortRealize          thrpt    4   9764.645 ±  6352.699  ops/s
normalSortTest.MergeSortTest.TestInnerSortRealize          thrpt    4   2833.303 ±   483.073  ops/s
normalSortTest.RadixSortTest.TestInnerSortRealize          thrpt    4   3862.049 ±  3743.130  ops/s
normalSortTest.ShellSortTest.TestInnerSortRealize          thrpt    4   4150.777 ±   237.711  ops/s
quickSortTest.QuickSortDuplexingTest.TestInnerSortRealize  thrpt    4  15079.496 ±  7921.672  ops/s
quickSortTest.QuickSortOptTest.TestInnerSortRealize        thrpt    4  19513.197 ± 12820.824  ops/s
quickSortTest.QuickSortSimplexTest.TestInnerSortRealize    thrpt    4   4347.717 ±  1105.995  ops/s
simpleSortTest.BubbleSortTest.TestInnerSortRealize         thrpt    4   1780.624 ±    82.313  ops/s
simpleSortTest.HeapSortTest.TestInnerSortRealize           thrpt    4   6892.012 ±  2643.572  ops/s
simpleSortTest.InsertSortTest.TestInnerSortRealize         thrpt    4   9119.023 ±  3375.271  ops/s
simpleSortTest.SelectSortTest.TestInnerSortRealize         thrpt    4   3108.758 ±   284.871  ops/s

• in conclusion

  • The sorting of the insertion change is the best, 19513.197 ± 12820.824 times per second, but ± 12820.824 also indicates that the algorithm is unstable every time.
  • The bubble sort performance is the most stable, at 1,780.624 ± 82.313 times per second.

• JMH trap

• JMH plugin

• JMH visualization

• Please refer to the following blog:

• JMH, an essential tool for performance tuning

• Reference blog

  • Use JMH for Benchmark benchmark testing
  • Use JMH for Java microbenchmarks