.NET 6 - StringBuilder vs. String Builder ObjectPool

sb-vs-sbpooled.cs

using System.Collections.Generic;
using System.Linq;
using System.Text;
using BenchmarkDotNet.Attributes;
using Microsoft.Extensions.ObjectPool;

namespace Benchmarks;

[MemoryDiagnoser]
public class Benchmark
{
    private List<string> _data;

    //.NET Core SDK=6.0.100-rc.2.21505.57
    //  [Host]     : .NET Core 6.0.0 (CoreCLR 6.0.21.48005, CoreFX 6.0.21.48005), X64 RyuJIT
    //  DefaultJob : .NET Core 6.0.0 (CoreCLR 6.0.21.48005, CoreFX 6.0.21.48005), X64 RyuJIT
    //
    // @abt_benjamin
    //|               Method |     Mean |     Error |    StdDev |  Gen 0 |  Gen 1 | Gen 2 | Allocated |
    //|--------------------- |---------:|----------:|----------:|-------:|-------:|------:|----------:|
    //| StringBuilder_NoPool | 2.076 us | 0.0227 us | 0.0212 us | 2.2202 | 0.2747 |     - |   37200 B |
    //| StringBuilder_Pooled | 1.130 us | 0.0076 us | 0.0067 us |      - |      - |     - |         - |

    [GlobalSetup]
    public void GlobalSetup()
    {
        _data = Enumerable.Range(0, 200)
            .Select(x => new string('a', 80)).ToList();

        _sbPool = ObjectPool.Create<StringBuilder>();
    }

    [Benchmark]
    public void StringBuilder_NoPool()
    {
        StringBuilder sb = new();

        foreach (var entry in _data)
        {
            var e = entry;
            sb.Append(e);
        }
    }

    private ObjectPool<StringBuilder> _sbPool;
    [Benchmark]
    public void StringBuilder_Pooled()
    {
        StringBuilder sb = _sbPool.Get();

        foreach (var entry in _data)
        {
            var e = entry;
            sb.Append(e);
        }

        sb.Clear();
        _sbPool.Return(sb);
    }
}