CollectToListBenchmark.java

/*
 * Copyright Gunnar Morling.
 *
 * Licensed under the Apache Software License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
 */
package dev.morling;

import java.util.List;
import java.util.Random;
import java.util.concurrent.ThreadLocalRandom;
import java.util.stream.Collectors;

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.infra.Blackhole;

public class CollectToListBenchmark {

    @State(Scope.Thread)
    public static class MyState {
        Random random = ThreadLocalRandom.current();
    }

    @Benchmark
    @BenchmarkMode(Mode.Throughput)
    public void sequentialCollector(MyState state, Blackhole blackhole) {
        List<Long> longs = state.random.ints(100000)
                .map(Math::abs)
                .mapToObj(Long::valueOf)
                .map(i -> i * 2)
                .collect(Collectors.toList());

        blackhole.consume(longs);
    }

    @Benchmark
    @BenchmarkMode(Mode.Throughput)
    public void sequentialToList(MyState state, Blackhole blackhole) {
        List<Long> longs = state.random.ints(100000)
                .map(Math::abs)
                .mapToObj(Long::valueOf)
                .map(i -> i * 2)
                .toList();

        blackhole.consume(longs);
    }

    @Benchmark
    @BenchmarkMode(Mode.Throughput)
    public void parallelCollector(MyState state, Blackhole blackhole) {
        List<Long> longs = state.random.ints(100000)
                .parallel()
                .map(Math::abs)
                .mapToObj(Long::valueOf)
                .map(i -> i * 2)
                .collect(Collectors.toList());

        blackhole.consume(longs);
    }

    @Benchmark
    @BenchmarkMode(Mode.Throughput)
    public void parallelToList(MyState state, Blackhole blackhole) {
        List<Long> longs = state.random.ints(100000)
                .parallel()
                .map(Math::abs)
                .mapToObj(Long::valueOf)
                .map(i -> i * 2)
                .toList();

        blackhole.consume(longs);
    }
}