ArrayEscapeAnalysis.java

import org.openjdk.jmh.annotations.*;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.concurrent.TimeUnit;

@State(Scope.Benchmark)
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@Warmup(iterations = 5, time = 200, timeUnit = TimeUnit.MILLISECONDS)
@Measurement(iterations = 5, time = 200, timeUnit = TimeUnit.MILLISECONDS)
@Fork(1)
public class ArrayEscapeAnalysis {

    @Param({"16"})
    private int size;
    private final int finalSize = 16;
    private static final int staticFinalSize = 16;

    @Benchmark
    public int arrayListNoEscapeUnknown() {
        final ArrayList<?> list = new ArrayList<>(size);
        return list.size();
    }

    @Benchmark
    public int arrayListNoEscapeFinal() {
        final ArrayList<?> list = new ArrayList<>(finalSize);
        return list.size();
    }

    @Benchmark
    public int arrayListNoEscapeStaticFinal() {
        final ArrayList<?> list = new ArrayList<>(staticFinalSize);
        return list.size();
    }

    @Benchmark
    public int arrayNoEscapeUnknown() {
        final byte[] bytes = new byte[size];
        return bytes.length;
    }

    @Benchmark
    public int arrayNoEscapeFinal() {
        final byte[] bytes = new byte[finalSize];
        return bytes.length;
    }

    @Benchmark
    public int arrayNoEscapeStaticFinal() {
        final byte[] bytes = new byte[staticFinalSize];
        return bytes.length;
    }


}