twillouer/ToArrayBench.java

## ToArrayBench.java
@State(Scope.Benchmark)
public class ToArrayBench {

    ArrayList<Byte> list;

    @Setup
    public void setup() throws Throwable
    {
        list = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            list.add((byte) i);
        }
    }

    @Benchmark
    public void zero_sized_array()
    {
        list.toArray(new Byte[0]);
    }

    @Benchmark
    public void simple_toArray()
    {
        list.toArray();
    }

    @Benchmark
    public void sized_array_from_list()
    {
        list.toArray(new Byte[list.size()]);
    }

    @Benchmark
    public void sized_array_fixed_size()
    {
        list.toArray(new Byte[100]);
    }

    @Benchmark
    public void defensive_copy()
    {
        new ArrayList<>(list);
    }

    public static void main(String[] args) throws RunnerException, IOException
    {
        Options opt = new OptionsBuilder().include(".*" + ToArrayBench.class.getSimpleName() + ".*")
                .warmupIterations(20)
                .warmupTime(TimeValue.seconds(1))
                .measurementIterations(20)
                .timeUnit(TimeUnit.MILLISECONDS)
                .forks(1)
                // .addProfiler(LinuxPerfProfiler.class)
                .build();

        new Runner(opt).run();
    }
}
	@State(Scope.Benchmark)
	public class ToArrayBench {

	ArrayList<Byte> list;

	@Setup
	public void setup() throws Throwable
	{
	list = new ArrayList<>();
	for (int i = 0; i < 10; i++) {
	list.add((byte) i);
	}
	}

	@Benchmark
	public void zero_sized_array()
	{
	list.toArray(new Byte[0]);
	}

	@Benchmark
	public void simple_toArray()
	{
	list.toArray();
	}

	@Benchmark
	public void sized_array_from_list()
	{
	list.toArray(new Byte[list.size()]);
	}

	@Benchmark
	public void sized_array_fixed_size()
	{
	list.toArray(new Byte[100]);
	}

	@Benchmark
	public void defensive_copy()
	{
	new ArrayList<>(list);
	}

	public static void main(String[] args) throws RunnerException, IOException
	{
	Options opt = new OptionsBuilder().include("." + ToArrayBench.class.getSimpleName() + ".")
	.warmupIterations(20)
	.warmupTime(TimeValue.seconds(1))
	.measurementIterations(20)
	.timeUnit(TimeUnit.MILLISECONDS)
	.forks(1)
	// .addProfiler(LinuxPerfProfiler.class)
	.build();

	new Runner(opt).run();
	}
	}
Benchmark	Mode	Samples	Score	Error	Units
c.d.m.b.m.ToArrayBench.defensive_copy	thrpt	200	73_431_578,798	± 875202,665	ops/s
c.d.m.b.m.ToArrayBench.simple_toArray	thrpt	200	76_845_735,280	± 710117,405	ops/s
c.d.m.b.m.ToArrayBench.sized_array_fixed_size	thrpt	200	16_077_751,085	± 155382,904	ops/s
c.d.m.b.m.ToArrayBench.sized_array_from_list	thrpt	200	24_524_222,665	± 311064,966	ops/s
c.d.m.b.m.ToArrayBench.zero_sized_array	thrpt	200	34_209_908,158	± 447488,028	ops/s
Benchmark	Mode	Cnt	Score	Error	Units
ToArrayBench.defensive_copy	thrpt	200	16 714 192	± 129515,217	ops/s
ToArrayBench.simple_toArray	thrpt	200	17 918 950	± 102801,298	ops/s
ToArrayBench.sized_array_fixed_size	thrpt	200	5 799 136	± 65921,564	ops/s
ToArrayBench.sized_array_from_list	thrpt	200	5 643 162	± 85215,009	ops/s
ToArrayBench.zero_sized_array	thrpt	200	6 529 068	± 78960,062	ops/s