包含，存在和任何的性能基准测试

问题描述 投票：55回答：3

我一直在寻找Contains，Exists和Any方法之间的性能基准测试。我只想出于好奇而发现这一点，因为我总是在这些中感到困惑。关于SO的许多问题描述了这些方法的定义，例如：

  1. List<T>
  2. LINQ Ring: Any() vs Contains() for Huge Collections
  3. Linq .Any VS .Exists - Whats the difference?

所以我决定自己做。我将其添加为答案。对结果有任何更多见解是最受欢迎的。我还对数组进行了基准测试以查看结果

c# performance benchmarking
3个回答
60
投票

根据文件：

List.Exists（对象方法）

确定List（T）是否包含与指定谓词定义的条件匹配的元素。

IEnumerable.Any（扩展方法）

确定序列的任何元素是否满足条件。

List.Contains（对象方法）

确定元素是否在List中。

标杆：

码：

LINQ extension methods - Any() vs. Where() vs. Exists()

结果

    static void Main(string[] args)
    {
        ContainsExistsAnyShort();

        ContainsExistsAny();
    }

    private static void ContainsExistsAny()
    {
        Console.WriteLine("***************************************");
        Console.WriteLine("********* ContainsExistsAny ***********");
        Console.WriteLine("***************************************");

        List<int> list = new List<int>(6000000);
        Random random = new Random();
        for (int i = 0; i < 6000000; i++)
        {
            list.Add(random.Next(6000000));
        }
        int[] arr = list.ToArray();

        find(list, arr);
    }

    private static void ContainsExistsAnyShort()
    {
        Console.WriteLine("***************************************");
        Console.WriteLine("***** ContainsExistsAnyShortRange *****");
        Console.WriteLine("***************************************");

        List<int> list = new List<int>(2000);
        Random random = new Random();
        for (int i = 0; i < 2000; i++)
        {
            list.Add(random.Next(6000000));
        }
        int[] arr = list.ToArray();

        find(list, arr);
    }

    private static void find(List<int> list, int[] arr)
    {
        Random random = new Random();
        int[] find = new int[10000];
        for (int i = 0; i < 10000; i++)
        {
            find[i] = random.Next(6000000);
        }

        Stopwatch watch = Stopwatch.StartNew();
        for (int rpt = 0; rpt < 10000; rpt++)
        {
            list.Contains(find[rpt]);
        }
        watch.Stop();
        Console.WriteLine("List/Contains: {0:N0}ms", watch.ElapsedMilliseconds);

        watch = Stopwatch.StartNew();
        for (int rpt = 0; rpt < 10000; rpt++)
        {
            list.Exists(a => a == find[rpt]);
        }
        watch.Stop();
        Console.WriteLine("List/Exists: {0:N0}ms", watch.ElapsedMilliseconds);

        watch = Stopwatch.StartNew();
        for (int rpt = 0; rpt < 10000; rpt++)
        {
            list.Any(a => a == find[rpt]);
        }
        watch.Stop();
        Console.WriteLine("List/Any: {0:N0}ms", watch.ElapsedMilliseconds);

        watch = Stopwatch.StartNew();
        for (int rpt = 0; rpt < 10000; rpt++)
        {
            arr.Contains(find[rpt]);
        }
        watch.Stop();
        Console.WriteLine("Array/Contains: {0:N0}ms", watch.ElapsedMilliseconds);

        Console.WriteLine("Arrays do not have Exists");

        watch = Stopwatch.StartNew();
        for (int rpt = 0; rpt < 10000; rpt++)
        {
            arr.Any(a => a == find[rpt]);
        }
        watch.Stop();
        Console.WriteLine("Array/Any: {0:N0}ms", watch.ElapsedMilliseconds);
    }
46
投票

最快的方法是使用*************************************** ***** ContainsExistsAnyShortRange ***** *************************************** List/Contains: 96ms List/Exists: 146ms List/Any: 381ms Array/Contains: 34ms Arrays do not have Exists Array/Any: 410ms *************************************** ********* ContainsExistsAny *********** *************************************** List/Contains: 257,996ms List/Exists: 379,951ms List/Any: 884,853ms Array/Contains: 72,486ms Arrays do not have Exists Array/Any: 1,013,303ms 。 HashSet的Contains是O（1）。

我拿了你的代码并为HashSet添加了一个基准.HashSet<int>的性能成本几乎为零。

HashSet<int> set = new HashSet<int>(list);

结果

void Main()
{
    ContainsExistsAnyShort();

    ContainsExistsAny();
}

private static void ContainsExistsAny()
{
    Console.WriteLine("***************************************");
    Console.WriteLine("********* ContainsExistsAny ***********");
    Console.WriteLine("***************************************");

    List<int> list = new List<int>(6000000);
    Random random = new Random();
    for (int i = 0; i < 6000000; i++)
    {
        list.Add(random.Next(6000000));
    }
    int[] arr = list.ToArray();
    HashSet<int> set = new HashSet<int>(list);

    find(list, arr, set);

}

private static void ContainsExistsAnyShort()
{
    Console.WriteLine("***************************************");
    Console.WriteLine("***** ContainsExistsAnyShortRange *****");
    Console.WriteLine("***************************************");

    List<int> list = new List<int>(2000);
    Random random = new Random();
    for (int i = 0; i < 2000; i++)
    {
        list.Add(random.Next(6000000));
    }
    int[] arr = list.ToArray();
    HashSet<int> set = new HashSet<int>(list);

    find(list, arr, set);

}

private static void find(List<int> list, int[] arr, HashSet<int> set)
{
    Random random = new Random();
    int[] find = new int[10000];
    for (int i = 0; i < 10000; i++)
    {
        find[i] = random.Next(6000000);
    }

    Stopwatch watch = Stopwatch.StartNew();
    for (int rpt = 0; rpt < 10000; rpt++)
    {
        list.Contains(find[rpt]);
    }
    watch.Stop();
    Console.WriteLine("List/Contains: {0}ms", watch.ElapsedMilliseconds);

    watch = Stopwatch.StartNew();
    for (int rpt = 0; rpt < 10000; rpt++)
    {
        list.Exists(a => a == find[rpt]);
    }
    watch.Stop();
    Console.WriteLine("List/Exists: {0}ms", watch.ElapsedMilliseconds);

    watch = Stopwatch.StartNew();
    for (int rpt = 0; rpt < 10000; rpt++)
    {
        list.Any(a => a == find[rpt]);
    }
    watch.Stop();
    Console.WriteLine("List/Any: {0}ms", watch.ElapsedMilliseconds);

    watch = Stopwatch.StartNew();
    for (int rpt = 0; rpt < 10000; rpt++)
    {
        arr.Contains(find[rpt]);
    }
    watch.Stop();
    Console.WriteLine("Array/Contains: {0}ms", watch.ElapsedMilliseconds);

    Console.WriteLine("Arrays do not have Exists");

    watch = Stopwatch.StartNew();
    for (int rpt = 0; rpt < 10000; rpt++)
    {
        arr.Any(a => a == find[rpt]);
    }
    watch.Stop();
    Console.WriteLine("Array/Any: {0}ms", watch.ElapsedMilliseconds);

    watch = Stopwatch.StartNew();
    for (int rpt = 0; rpt < 10000; rpt++)
    {
        set.Contains(find[rpt]);
    }
    watch.Stop();
    Console.WriteLine("HashSet/Contains: {0}ms", watch.ElapsedMilliseconds);
}
4
投票

值得一提的是，这种比较有点不公平，因为*************************************** ***** ContainsExistsAnyShortRange ***** *************************************** List/Contains: 65ms List/Exists: 106ms List/Any: 222ms Array/Contains: 20ms Arrays do not have Exists Array/Any: 281ms HashSet/Contains: 0ms *************************************** ********* ContainsExistsAny *********** *************************************** List/Contains: 120522ms List/Exists: 250445ms List/Any: 653530ms Array/Contains: 40801ms Arrays do not have Exists Array/Any: 522371ms HashSet/Contains: 3ms 类不拥有Array方法，它通过连续的Contains()使用IEnumerable<T>的扩展方法，因此它没有针对Enumerator实例进行优化;另一方面，Array有自己的实现，完全针对所有尺寸进行了优化。

为了比较公平，你可以使用为HashSet<T>实例实现的静态方法int Array.IndexOf()，即使它使用Array循环稍微高于for。

话虽如此，Enumerator的表现类似于HashSet<T>.Contains()的小集合，我想说，最多5个元素，对大型集合更有效。

最新问题
© www.soinside.com 2019 - 2024. All rights reserved.