C#内List VS hashset性能对比

来源：互联网发布：监控显示无网络视频编辑：程序博客网时间：2024/06/02 04:17

昨天在看客户端代码时看到缓存用了List，直觉告诉我应该替换成HashSet，尼玛一个O(N)，一个O(1)，不用直觉都知道用哪个。

而有同事说性能不一定好，好嘛，我们来个perfonmance test.

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Diagnostics;namespace listtest{    class Program    {        static void Main(string[] args)        {            int times = 10000000;            for (int listSize = 1; listSize < 10; listSize++)            {                List<string> list = new List<string>();                HashSet<string> hashset = new HashSet<string>();                for (int i = 0; i < listSize; i++)                {                    list.Add("string" + i.ToString());                    hashset.Add("string" + i.ToString());                }                Stopwatch timer = new Stopwatch();                timer.Start();                for (int i = 0; i < times; i++)                {                    list.Remove("string0");                    list.Add("string0");                }                timer.Stop();                Console.WriteLine(listSize.ToString() + " item LIST strs time: " + timer.ElapsedMilliseconds.ToString() + "ms");                timer = new Stopwatch();                timer.Start();                for (int i = 0; i < times; i++)                {                    hashset.Remove("string0");                    hashset.Add("string0");                }                timer.Stop();                Console.WriteLine(listSize.ToString() + " item HASHSET strs time: " + timer.ElapsedMilliseconds.ToString() + "ms");                Console.WriteLine();            }            for (int listSize = 1; listSize < 50; listSize += 3)            {                List<object> list = new List<object>();                HashSet<object> hashset = new HashSet<object>();                for (int i = 0; i < listSize; i++)                {                    list.Add(new object());                    hashset.Add(new object());                }                object objToAddRem = list[0];                Stopwatch timer = new Stopwatch();                timer.Start();                for (int i = 0; i < times; i++)                {                    list.Remove(objToAddRem);                    list.Add(objToAddRem);                }                timer.Stop();                Console.WriteLine(listSize.ToString() + " item LIST objs time: " + timer.ElapsedMilliseconds.ToString() + "ms");                timer = new Stopwatch();                timer.Start();                for (int i = 0; i < times; i++)                {                    hashset.Remove(objToAddRem);                    hashset.Add(objToAddRem);                }                timer.Stop();                Console.WriteLine(listSize.ToString() + " item HASHSET objs time: " + timer.ElapsedMilliseconds.ToString() + "ms");                Console.WriteLine();            }            Console.ReadLine();        }    }}

可以明显看出来，hashset的优势，Talk is easy, show the code!

0 0