计算完成处理线程代码 C# 的挂起时间

Question

我有一个带线程的代码，我想显示完成处理的等待时间。按钮 1 调用函数 "Function1()" 以 1024 字节的块读取文件，在 while 循环中控制，直到结束的文件。在 "While loop" 中有一个 "foreach loop" 称为 "Function2()"。我开始 "while loop" 开始时的计时器并在 "while loop" 结束时停止。在那之后我正在尝试计算大约等待时间，首先知道 "while loop" 将处理的迭代次数。然后我保存 "elapsed time for the first iteration"（比方说 T1），然后我将它乘以迭代次数。

这将是

PendingTime = T1*Iterations.

那我做

PendingTime = PendingTime - Ti, where Ti is the ElapsedTime of the ith iteration.

问题是当我尝试使用真实代码时，T1*Iterations 的乘法给出了 402，实际上处理需要12秒。

也许一些专家可以看出我做错了什么。提前致谢。

代码如下所示：

    async void button1_Click(object sender, EventArgs e)
    {
        //Some code
        await Task.Run(() => Function1(inputfile, cts.Token), cts.Token);
        //Some code
    }

    public void Function2()
    {
        //Some code
    }       

    public void Function1(string inputfile, CancellationToken token)
    {
        int buffer = 1024;
        int IterationCounter = 0;
        decimal Iterations = 1;  
        int PendingTime = 0;            

        using (BinaryReader reader = new BinaryReader(File.Open(inputfile, FileMode.Open)))
        {
            FileLength = (int)reader.BaseStream.Length;
            Iterations = (int)FileLength/buffer;                            

            while (chunk.Length > 0)
            {     
                Stopwatch sw1 = Stopwatch.StartNew(); //Start time counter              
                //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
                //some code 
                chunk = reader.ReadBytes(buffer);

                foreach (byte data in chunk)
                {
                    //Some code
                    Function2(); //Call to Function2
                }
                //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 

                //Checking if it is the first iteration to save the pending time
                //Pending time would be the elapsed time for the first iteration
                //multiplied by the number of iterations (FileLength/1024).
                sw1.Stop(); //Stop time counter

                if (IterationCounter == 1)
                {
                    PendingTime =  (int)((decimal)Math.Round(sw1.Elapsed.TotalMilliseconds / 1000, 4)*Iterations);                      
                }                   
                //Show in TexBox1 the pending time
                TextBox1.Invoke((MethodInvoker)delegate
                {
                    PendingTime = PendingTime - (int)Math.Round(sw1.Elapsed.TotalMilliseconds / 1000, 4);                 
                    TextBox1.Text = PendingTime + " s";
                });
            }
        }
    }

更新：

我正在根据 Peter Duniho 的示例使用以下代码进行测试。

可以用任何文件（即txt文件）进行测试。我已经用 5MB 的 txt 文件进行了测试，执行时间为 3 秒，但等待时间在 TextBox1 中始终显示为零。我哪里错了？

注意：我更改了这个：

double timePerIteration = sw1.Elapsed / ++IterationCounter;

至此

double timePerIteration = sw1.ElapsedMilliseconds/1000/ ++IterationCounter;

因为我收到错误：

Operator '/' cannot be applied to operands of type 'System.TimeSpan' and 'int' (CS0019)

到目前为止的代码是。感谢您的帮助。

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Drawing;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace TestTimer
{
    public partial class MainForm : Form
    {
        CancellationTokenSource cts = new CancellationTokenSource();
        string filename = "";
        long FileLength;
        FileInfo fInfo;
        Stopwatch sw1 =  new Stopwatch();

        public MainForm()
        {
            InitializeComponent();
        }

        void BtnSelectFileClick(object sender, EventArgs e)
        {

            OpenFileDialog ofd = new OpenFileDialog();
            ofd.Title = "Select file";
            DialogResult dr = ofd.ShowDialog();

            if (dr == DialogResult.OK)
            {
                filename = ofd.FileName;
                fInfo = new FileInfo(filename);
            }
            else
            {
                MessageBox.Show("File not found");
                return;
            }           
        }   

        async void BtnRunProcessClick(object sender, System.EventArgs e)
        {

            cts = new CancellationTokenSource();            
            await Task.Run(() => Function1(filename, cts.Token), cts.Token);    
        }

    public void Function1(string inputfile, CancellationToken token)
    {
        int buffer = 1024;
        int IterationCounter = 0;
        int Iterations = 0;  
        double pendingTime = 0;            

        using (BinaryReader reader = new BinaryReader(File.Open(inputfile, FileMode.Open)))
        {
            FileLength = (int)reader.BaseStream.Length;
            Iterations = (int)FileLength/buffer;                           
            byte[] chunk;          

            sw1 = Stopwatch.StartNew(); //Start time counter

            while (true)
            {                               
                chunk = reader.ReadBytes(buffer);

                if (chunk.Length == 0) {break;}

                foreach  (byte data in chunk)
                {
                    Thread.Sleep(90/100);
                }

                // pendingTime is the current average time-per-iteration,
                // times the number of iterations left
                double timePerIteration = sw1.ElapsedMilliseconds/1000/ ++IterationCounter;
                pendingTime = timePerIteration * (Iterations - IterationCounter);

                TextBox1.Invoke((MethodInvoker)delegate
                {
                    // Let string.Format() take care of rounding for you
                    TextBox1.Text = string.Format("{0:0} s", pendingTime / 1000);
                });
            }
            MessageBox.Show("Execution time: " + string.Format("{0:0} s", sw1.ElapsedMilliseconds / 1000) );
        }
    }               

    }
}

Answer 1

我不明白您 post 编写的代码是如何实际编译的，更不用说工作了。 FileLength 变量似乎没有被声明，并且您永远不会增加 IterationCounter 变量，每次迭代都会给您一个负的 PendingTime 值。即使您增加了计数器，您的 PendingTime 变量的实际含义也会从计数器为 1 时执行的块和稍后当您从当前 PendingTime 中减去经过的时间时发生变化变量。

这表明您 post 编辑的代码并不是您正在使用的代码，因为显示的剩余时间总是负数（即使假设 FileLength 的声明刚刚得到由于某种原因不小心从你的 post 上掉了）。为了争论，我将添加一个执行递增的语句…

正如评论者 Chris 所说，当每次迭代的实际持续时间可能会有所不同时，就像这里的情况一样，您要做的最好的事情就是对当前迭代之前的所有迭代进行平均。即使这样也可能导致错误的剩余时间显示，每次迭代都会有相当大的变化（特别是如果迭代次数很少），但至少它更有可能接近。

像这样的东西可能更适合你：

public void Function1(string inputfile, CancellationToken token)
{
    int buffer = 1024;
    int IterationCounter = 0;
    int Iterations;

    using (BinaryReader reader = new BinaryReader(File.Open(inputfile, FileMode.Open)))
    {
        if (reader.BaseStream.Length == 0)
        {
            // nothing to do
            return;
        }

        // NOTE: this won't work for files with length > int.MaxValue!
        // Your original code has the same limitation, and I have not
        // bothered to change that.

        // Now that we know for sure the length is > 0, we can
        // do the following to ensure a correct iteration count
        Iterations = ((int)reader.BaseStream.Length - 1) / buffer + 1;

        Stopwatch sw1 = Stopwatch.StartNew();

        while (chunk.Length > 0)
        {     
            //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
            //some code 
            chunk = reader.ReadBytes(buffer);

            foreach (byte data in chunk)
            {
                //Some code
                Function2(); //Call to Function2
            }
            //++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 

            // pendingTime is the current average time-per-iteration,
            // times the number of iterations left
            double timePerIteration = sw1.ElapsedMilliseconds / ++IterationCounter,
                pendingTime = timePerIteration *
                    (Iterations - IterationCounter);

            //Show in TexBox1 the pending time
            TextBox1.Invoke((MethodInvoker)delegate
            {
                // Let string.Format() take care of rounding for you
                TextBox1.Text = string.Format("{0:0} s", pendingTime / 1000);
            });
        }
    }
}

除非您保证输入文件的长度始终恰好是 1024 字节的倍数，否则您在计算总迭代次数时也有错误。我也在上面修复了这个问题。

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