加速c#循环

本文关键字：循环 加速 | 更新日期: 2023-09-27 18:16:04

我正试图找到一种快速的方法来加速以下for loops。(只是有趣的理论东西)

我有以下程序

using System;
using System.Collections;
using System.Diagnostics;
namespace SpeedTest
{
    class Program
    {
        static void Main(string[] args)
        {
            Stopwatch timer = new Stopwatch();
            timer.Start();
            ArrayList widgets = new ArrayList(50000);
            for (int i = 0; i < widgets.Capacity; i++)
            {
                widgets.Add(new Widget(i));
            }
            string ProcessingMessages = "";
            for (int i = 0; i < widgets.Count; i++)
            {
                Widget widgetToProcess = (Widget)widgets[i];
                ProcessingMessages += widgetToProcess.ProcessWidget();
                ProcessingMessages += "'r'n";
            }
            Console.WriteLine(ProcessingMessages);
            timer.Stop();
            Console.WriteLine(timer.Elapsed);
            Console.ReadLine();
        }
    }
    class Widget
    {
        public Widget()
        {
            this.CreatedDateTime = DateTime.Now;
        }
        public Widget(int ID) : this()
        {
            this.ID = ID;
        }
        public DateTime CreatedDateTime { get; set; }
        public int ID { get; set; }
        public string ProcessWidget()
        {
            int Z = this.ID + this.ID;
            string Message = "Widget ID " + this.ID;
            Message += " was created on ";
            Message += CreatedDateTime.Year + "-" + CreatedDateTime.Month + "-" + CreatedDateTime.Day + ", at ";
            Message += CreatedDateTime.Hour + ":" + CreatedDateTime.Minute + ", with a value of ";
            Message += Z.ToString();
            return Message;
        }
    }
}

我如何加速这些for loops本身?我知道实现并行会很有用，比如

for (int i = 0; i < widgets.Count; i += 10)
            {
                Widget widgetToProcess1 = (Widget)widgets[i];
                Widget widgetToProcess2 = (Widget)widgets[i+1];
                Widget widgetToProcess3 = (Widget)widgets[i+2];
                Widget widgetToProcess4 = (Widget)widgets[i+3];
                Widget widgetToProcess5 = (Widget)widgets[i+4];
                Widget widgetToProcess6 = (Widget)widgets[i + 5];
                Widget widgetToProcess7 = (Widget)widgets[i + 6];
                Widget widgetToProcess8 = (Widget)widgets[i + 7];
                Widget widgetToProcess9 = (Widget)widgets[i + 8];
                Widget widgetToProcess10 = (Widget)widgets[i + 9];
                ProcessingMessages += widgetToProcess1.ProcessWidget() + "'r'n" +
                    widgetToProcess2.ProcessWidget() + "'r'n" +
                    widgetToProcess3.ProcessWidget() + "'r'n" +
                    widgetToProcess4.ProcessWidget() + "'r'n" +
                    widgetToProcess5.ProcessWidget() + "'r'n" +
                    widgetToProcess6.ProcessWidget() + "'r'n" +
                    widgetToProcess7.ProcessWidget() + "'r'n" +
                    widgetToProcess8.ProcessWidget() + "'r'n" +
                    widgetToProcess9.ProcessWidget() + "'r'n" +
                    widgetToProcess10.ProcessWidget() + "'r'n";
             }

但是这些都是手工写的。我正试图找到一种方法来动态分解一个大的任务/数组大小和运行这些块更快。

寻找一些简单的想法/概念。或者，是否有比使用for环路更好的替代方案。

加速c#循环

对于初学者来说，你在一个紧密的循环中做字符串连接-不好，看看StringBuilder。

其次，您要在您的时间安排中包括设置您的测试场景。

第三，不清楚处理for循环的成本与ProcessWidget()方法的成本之间的相对成本。当然，任何优化将发生在这个方法内?

向下滚动查看ProcessWidget()方法，您还可以从删除所有字符串连接并替换为一个大的string.Format()调用或使用StringBuilder中受益。此外，ID和CreatedDateTime看起来像不可变的字段，也许值得将它们定义为readonly并在构造函数中预先创建字符串描述(如果ProcessWidget()可能被多次调用)。

您也可以考虑使用:

widgets.Cast<Widget>().AsParallel().ForAll(widgetToProcess => {...});

这将提高您的进程的性能，从超过4分钟到不到30秒(取决于CPU配置)。

可以通过以下方式提高总体速度:使用StringBuilder并将控制台输出移到ProcessWidget调用中，然后将数组填充和处理放入Parallel中。为总运行时间为~7秒

修改后的代码:

using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
using System.Collections;
using System.Diagnostics;
namespace parallelFor
{
    class Program
    {
        static void Main(string[] args)
        {
            Stopwatch timer = new Stopwatch();
            timer.Start();
            int size = 50000;
            ArrayList widgets = new ArrayList(size);
            Parallel.For(0, size, i =>
            {
                Widget w = new Widget((int)i);
                widgets.Add(w);
                w.ProcessWidget();
            });

            timer.Stop();
            Console.WriteLine(timer.Elapsed);
            Console.ReadLine();
        }
    }
    class Widget
    {
        public Widget()
        {
            this.CreatedDateTime = DateTime.Now;
        }
        public Widget(int ID)
            : this()
        {
            this.ID = ID;
        }
        public DateTime CreatedDateTime { get; set; }
        public int ID { get; set; }
        public void ProcessWidget()
        {
        int Z = this.ID + this.ID;
        string Message = "Widget ID " + this.ID;
        Message += " was created on ";
        Message += CreatedDateTime.Year + "-" + CreatedDateTime.Month + "-" + CreatedDateTime.Day + ", at ";
        Message += CreatedDateTime.Hour + ":" + CreatedDateTime.Minute + ", with a value of ";
        Message += Z.ToString();
        Console.WriteLine(Message);
        }
    }
}
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