C# Linq.FirstOrDefault、Linq.Where、Linq.AsParallel、List.Exists、List.Find、Dictionar.TryGetValue、HashSet.Contains 性能的比较

今天我们来比较一下集合检索方法性能更优问题，测试代码

public class Entity
{
    public int Id { get; set; }
    public int No { get; set; }
    public string Col1 { get; set; }
    public string Col2 { get; set; }
    public string Col3 { get; set; }
    public string Col4 { get; set; }
    public string Col5 { get; set; }
    public string Col6 { get; set; }
    public string Col7 { get; set; }
    public string Col8 { get; set; }
    public string Col9 { get; set; }
    public string Col10 { get; set; }
}
static void TestFindVelocity(int totalDataCount, int executeCount)
{
    #region 构造数据
    List<Entity> datas = new List<Entity>();
    for (int i = 0; i < totalDataCount; i++)
    {
        var item = new Entity
        {
            No = i + 1,
            Col1 = Guid.NewGuid().ToString("N"),
            Col2 = Guid.NewGuid().ToString("N"),
            Col3 = Guid.NewGuid().ToString("N"),
            Col4 = Guid.NewGuid().ToString("N"),
            Col5 = Guid.NewGuid().ToString("N"),
            Col6 = Guid.NewGuid().ToString("N"),
            Col7 = Guid.NewGuid().ToString("N"),
            Col8 = Guid.NewGuid().ToString("N"),
            Col9 = Guid.NewGuid().ToString("N"),
            Col10 = Guid.NewGuid().ToString("N"),
        };
        datas.Add(item);
    }
    #endregion
    var dicDatas = datas.ToDictionary(x => x.No);
    var hashSetDatas = datas.ConvertAll<Tuple<int, int>>(x => new Tuple<int, int>(x.No, x.No + 1000)).ToHashSet();
    Stopwatch sw = new Stopwatch();
    Random random = new Random();
    Entity searchResult = null;
    bool searchResultBool = false;
    // 每次查询索引
    List<int> indexs = Enumerable.Range(1, executeCount).Select(x => random.Next(1, totalDataCount)).ToList();

    sw.Start();
    for (int i = 0; i < executeCount; i++)
    {
        searchResult = datas.FirstOrDefault(x => x.No == indexs[i]);
    }
    sw.Stop();
    Console.WriteLine($"list FirstOrDefault 耗时：{sw.ElapsedMilliseconds}");

    sw.Restart();
    for (int i = 0; i < executeCount; i++)
    {
        searchResult = datas.Where(x => x.No == indexs[i]).First();
    }
    sw.Stop();
    Console.WriteLine($"list Where+First 耗时：{sw.ElapsedMilliseconds}");

    sw.Restart();
    for (int i = 0; i < executeCount; i++)
    {
        searchResultBool = datas.Exists(x => x.No == indexs[i]);
    }
    sw.Stop();
    Console.WriteLine($"list Exist 耗时：{sw.ElapsedMilliseconds}");

    sw.Restart();
    for (int i = 0; i < executeCount; i++)
    {
        searchResult = datas.Find(x => x.No == indexs[i]);
    }
    sw.Stop();
    Console.WriteLine($"list Find 耗时：{sw.ElapsedMilliseconds}");

    sw.Restart();
    for (int i = 0; i < executeCount; i++)
    {
        dicDatas.TryGetValue(indexs[i], out searchResult);
    }
    sw.Stop();
    Console.WriteLine($"dictionary TryGetValue 耗时：{sw.ElapsedMilliseconds}");

    sw.Restart();
    for (int i = 0; i < executeCount; i++)
    {
        searchResultBool = hashSetDatas.Contains(new Tuple<int, int>(indexs[i], indexs[i] + 1000));
    }
    sw.Stop();
    Console.WriteLine($"Hashset contains 耗时：{sw.ElapsedMilliseconds}");
}

结果

(集合数量，测试次数)	Linq.FirstOrDefault	Linq.Where+First	List.Exists	List.Find	Dictionary.TryGetValue	HashSet.Contains
(100, 5000000)	4544	3521	1992	1872	66	924
(1000, 5000000)	41751	29417	20631	19490	70	869
(10000, 5000000)	466918	397425	276409	281647	85	946
(50000, 5000)	6292	4602	4252	3559	0	2
(500000, 5000)	56988	55568	48423	48395	1	5