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  • 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
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  • 原文地址:https://www.cnblogs.com/Cxiaoao/p/14674954.html
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