dotnet C# 字典 Dictionary 和 Hashtable 的性能对比

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;
using System.Collections;
using System.Collections.Generic;
using System.Linq;

[MemoryDiagnoser]
public class Program
{
    static void Main(string[] args) => BenchmarkSwitcher.FromAssemblies(new[] { typeof(Program).Assembly }).Run(args);

    private readonly Hashtable _table = new Hashtable(20, .1f);
    private readonly Dictionary<int, object> _dictionary = new Dictionary<int, object>(20);
    private readonly object[] _objects = Enumerable.Range(0, 20).Select(_ => new object()).ToArray();

    [Params(1, 3, 5, 7, 9, 20)]
    public int Count { get; set; }

    [Benchmark]
    public void WithHashtable()
    {
        for (int i = 0; i < Count; i++)
        {
            _table.Add(i, _objects[i]);
        }
        for (int i = 0; i < Count; i++)
        {
            if (_table.ContainsKey(i))
            {
                object o = _table[i];
            }
        }
        _table.Clear();
    }

    [Benchmark]
    public void WithDictionary()
    {
        for (int i = 0; i < Count; i++)
        {
            _dictionary.Add(i, _objects[i]);
        }
        for (int i = 0; i < Count; i++)
        {
            if (_dictionary.TryGetValue(i, out object o))
            {
            }
        }
        _dictionary.Clear();
    }
}