ConcatTest.java

import java.util.concurrent.TimeUnit;
import java.util.stream.*;
import java.util.*;

import org.openjdk.jmh.infra.Blackhole;
import org.openjdk.jmh.annotations.*;

@Warmup(iterations = 5, time = 1000, timeUnit = TimeUnit.MILLISECONDS)
@Measurement(iterations = 10, time = 1000, timeUnit = TimeUnit.MILLISECONDS)
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.MICROSECONDS)
@Fork(2)
@State(Scope.Benchmark)
public class ConcatTest {
    @Param({"100","10000","1000000"})
    private int n;

    private int[] input1;
    private int[] input2;

    @Setup
    public void setUp() {
        input1 = new Random(1).ints(n).toArray();
        input2 = new Random(2).ints(n).toArray();
    }

    @Benchmark
    public void SSS(Blackhole bh) {
        bh.consume(IntStream.concat(Arrays.stream(input1).filter(x -> x > 0), 
            Arrays.stream(input2).distinct()).sorted().toArray());
    }

    @Benchmark
    public void SSP(Blackhole bh) {
        bh.consume(IntStream.concat(Arrays.stream(input1).filter(x -> x > 0), 
            Arrays.stream(input2).distinct()).parallel().sorted().toArray());
    }

    @Benchmark
    public void SPS(Blackhole bh) {
        bh.consume(IntStream.concat(Arrays.stream(input1).filter(x -> x > 0), 
            Arrays.stream(input2).parallel().distinct()).sequential().sorted().toArray());
    }

    @Benchmark
    public void SPP(Blackhole bh) {
        bh.consume(IntStream.concat(Arrays.stream(input1).filter(x -> x > 0), 
            Arrays.stream(input2).parallel().distinct()).sorted().toArray());
    }

    @Benchmark
    public void PSS(Blackhole bh) {
        bh.consume(IntStream.concat(Arrays.stream(input1).parallel().filter(x -> x > 0), 
            Arrays.stream(input2).distinct()).sequential().sorted().toArray());
    }

    @Benchmark
    public void PSP(Blackhole bh) {
        bh.consume(IntStream.concat(Arrays.stream(input1).parallel().filter(x -> x > 0), 
            Arrays.stream(input2).distinct()).sorted().toArray());
    }

    @Benchmark
    public void PPS(Blackhole bh) {
        bh.consume(IntStream.concat(Arrays.stream(input1).parallel().filter(x -> x > 0), 
            Arrays.stream(input2).parallel().distinct()).sequential().sorted().toArray());
    }

    @Benchmark
    public void PPP(Blackhole bh) {
        bh.consume(IntStream.concat(Arrays.stream(input1).parallel().filter(x -> x > 0), 
            Arrays.stream(input2).parallel().distinct()).sorted().toArray());
    }
}

result.txt

Benchmark           (n)  Mode  Cnt       Score       Error  Units
ConcatTest.PPP      100  avgt   20      23.078 ±     0.622  us/op
ConcatTest.PPP    10000  avgt   20    1128.889 ±     7.964  us/op
ConcatTest.PPP  1000000  avgt   20  393699.222 ± 56397.445  us/op
ConcatTest.PPS      100  avgt   20      16.412 ±     0.129  us/op
ConcatTest.PPS    10000  avgt   20    1816.782 ±    10.875  us/op
ConcatTest.PPS  1000000  avgt   20  476311.713 ± 19154.558  us/op
ConcatTest.PSP      100  avgt   20       9.877 ±     0.382  us/op
ConcatTest.PSP    10000  avgt   20     883.639 ±    13.596  us/op
ConcatTest.PSP  1000000  avgt   20  257921.422 ±  7649.434  us/op
ConcatTest.PSS      100  avgt   20       7.162 ±     0.241  us/op
ConcatTest.PSS    10000  avgt   20    1593.332 ±     7.961  us/op
ConcatTest.PSS  1000000  avgt   20  383920.286 ±  6650.890  us/op
ConcatTest.SPP      100  avgt   20      23.871 ±     0.285  us/op
ConcatTest.SPP    10000  avgt   20    1141.273 ±     9.310  us/op
ConcatTest.SPP  1000000  avgt   20  400582.847 ± 27330.492  us/op
ConcatTest.SPS      100  avgt   20      16.548 ±     0.175  us/op
ConcatTest.SPS    10000  avgt   20    1831.569 ±    13.582  us/op
ConcatTest.SPS  1000000  avgt   20  500736.204 ± 37932.197  us/op
ConcatTest.SSP      100  avgt   20       6.176 ±     0.043  us/op
ConcatTest.SSP    10000  avgt   20     907.855 ±     8.448  us/op
ConcatTest.SSP  1000000  avgt   20  264193.679 ±  6744.169  us/op
ConcatTest.SSS      100  avgt   20       7.094 ±     0.069  us/op
ConcatTest.SSS    10000  avgt   20    1542.820 ±    22.194  us/op
ConcatTest.SSS  1000000  avgt   20  350173.723 ±  7140.406  us/op