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Writing Random Data C# - Performance.

Posted on 2010-08-17
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Last Modified: 2013-12-17
Hi,

Ok I have some code below that I would like to improve - it works but it runs very slowly.

What I am trying to do is write a program that generates a "random" data file of a
size determined by the user in GB which is chosen as a multiple. so if they
select 5.5 the 5.5 GB of random data is written.

It runs really slowly in the generate data phase and I guess the file write phase.

Obviously I am not doing something correct and it performs poorly. My guess is
List<Byte> file_data = new List<Byte>();

So I am interested to see if the performance can be improved or are my expectations unrealistic ? :)

Thanks,

Ward.

using System;

using System.Collections.Generic;

using System.Collections;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using System.IO;



namespace FileGen

{

    public partial class Form1 : Form

    {

        private string file_name;

        decimal total_file_size;



        public Form1()

        {

            InitializeComponent();

        }



        private void fnUpdate_Progress(decimal position)

        {



            if (position % 1048576 == 0)

            {

                decimal percentage = (position / total_file_size) * 100;

                percentage = Math.Round(percentage, 2);

                label_Position.Text = position.ToString("#,##0") + " / " + total_file_size.ToString("#,##0") + " (" + percentage.ToString() + "%)";

                progressBar_File.Value = (int)percentage;

            }



            Application.DoEvents();

        }



        private void fnCalculate_File_Size(decimal gb)

        {

            decimal gigabyte = 1073741824;



            decimal temp_file_size = gb * gigabyte;

            total_file_size = temp_file_size;



            string temp_format = temp_file_size.ToString("#,##0");



            label_FileSize.Text = temp_format + " bytes.";

            Application.DoEvents();



        }



        private void button_Exit_Click(object sender, EventArgs e)

        {

            Application.Exit();

        }



        private void button_Path_Click(object sender, EventArgs e)

        {



            SaveFileDialog saveFileDialog1 = new SaveFileDialog();



            saveFileDialog1.Filter = "dat files (*.dat)|*.dat|All files (*.*)|*.*";

            saveFileDialog1.FilterIndex = 2;

            saveFileDialog1.RestoreDirectory = true;



            if (saveFileDialog1.ShowDialog() == DialogResult.OK)

            {               

                file_name = saveFileDialog1.FileName;

                textBox_Path.Text = file_name;

                button_Generate.Enabled = true;

            }



        }



        private void Form1_Load(object sender, EventArgs e)

        {

            comboFileSize.SelectedIndex = 11;

            file_name = "";

            progressBar_File.Minimum = 0;

            progressBar_File.Maximum = 100;

            progressBar_File.Step = 1;

            progressBar_File.Value = 0;

            label_FileSize.Text = "";

            label_Status.Text = "";

            label_Position.Text = "";

            fnCalculate_File_Size(4);

        }



        private Byte RandomNumber(int min, int max)

        {

            Random random = new Random();

            return (Byte)random.Next(min, max);

        }



        private void button_Generate_Click(object sender, EventArgs e)

        {



            List<Byte> file_data = new List<Byte>();

            Byte data_byte;

            decimal file_pos;



            if (file_name == "")

            {

                return;

            }



            // ---------------------------- Very SLOW Here ------------------------ 



            label_Status.Text = "Generating data...";

            Application.DoEvents();



            for (file_pos = 1; file_pos <= total_file_size; file_pos++)

            {

                data_byte = RandomNumber(0, 255);

                file_data.Add(data_byte);

                fnUpdate_Progress(file_pos);

            }                     



            FileStream fs1 = new FileStream(file_name, FileMode.OpenOrCreate,

            FileAccess.Write);

            BinaryWriter bw = new BinaryWriter(fs1);



            label_Status.Text = "Writing data to file...";

            Application.DoEvents();



            file_pos = 1;



            // ---------------------- Probably SLOW Here? -----------------------------



            foreach (Byte b in file_data)

            {

                bw.Write(b);

                fnUpdate_Progress(file_pos);

                file_pos++;

            }

            

            bw.Close();

            fs1.Close();



            Application.Exit();

        }





        private void comboFileSize_SelectedValueChanged(object sender, EventArgs e)

        {

            string gb_size;

            decimal gb;



            gb_size = (string)comboFileSize.SelectedItem;



            gb = Convert.ToDecimal(gb_size);



            fnCalculate_File_Size(gb);

        }

    }

}

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Comment
Question by:whorsfall
  • 2
4 Comments
 
LVL 62

Accepted Solution

by:
Fernando Soto earned 500 total points
ID: 33456959
Hi whorsfall;

I have modified your code to get better performance. Each time you make a function call you take a small hit but making the number of function calls to the random function and progress changing give a very big performance hit. Also waiting to the end to write the data to the file is not a good idea because the amount of memory needed to hold it. So getting a chunk of data and writing a chunk of data will increase performance. Also checking progress in the loop that creates the data and writes the data is better then making a call to find out that it is not needed yet will also slow you down a bit.

Fernando
using System;

using System.Collections.Generic;

using System.Collections;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Windows.Forms;

using System.IO;



namespace FileGen

{

    public partial class Form1 : Form

    {

        private string file_name;

        decimal total_file_size;



        public Form1()

        {

            InitializeComponent();

        }



        private void fnUpdate_Progress(decimal position)

        {



            decimal percentage = (position / total_file_size) * 100;

            percentage = Math.Round(percentage, 2);

            label_Position.Text = position.ToString("#,##0") + " / " + total_file_size.ToString("#,##0") + " (" + percentage.ToString() + "%)";

            progressBar_File.Value = (int)percentage;



            Application.DoEvents();

        }



        private void fnCalculate_File_Size(decimal gb)

        {

            decimal gigabyte = 1073741824;



            decimal temp_file_size = gb * gigabyte;

            total_file_size = temp_file_size;



            string temp_format = temp_file_size.ToString("#,##0");



            label_FileSize.Text = temp_format + " bytes.";

            Application.DoEvents();



        }



        private void button_Exit_Click(object sender, EventArgs e)

        {

            Application.Exit();

        }



        private void button_Path_Click(object sender, EventArgs e)

        {



            SaveFileDialog saveFileDialog1 = new SaveFileDialog();



            saveFileDialog1.Filter = "dat files (*.dat)|*.dat|All files (*.*)|*.*";

            saveFileDialog1.FilterIndex = 2;

            saveFileDialog1.RestoreDirectory = true;



            if (saveFileDialog1.ShowDialog() == DialogResult.OK)

            {

                file_name = saveFileDialog1.FileName;

                textBox_Path.Text = file_name;

                button_Generate.Enabled = true;

            }



        }



        private void Form1_Load(object sender, EventArgs e)

        {

            comboFileSize.SelectedIndex = 11;

            file_name = "";

            progressBar_File.Minimum = 0;

            progressBar_File.Maximum = 100;

            progressBar_File.Step = 1;

            progressBar_File.Value = 0;

            label_FileSize.Text = "";

            label_Status.Text = "";

            label_Position.Text = "";

            fnCalculate_File_Size(4);

        }



        private List<Byte> RandomNumber(int min, int max)

        {

            Random random = new Random();

            List<Byte> randList = new List<byte>();

            for (int r = 0; r < 4097; r++)

            {

                randList.Add((Byte)random.Next(min, max));

            }

            return randList;

        }



        private void button_Generate_Click(object sender, EventArgs e)

        {



            List<Byte> file_data = new List<Byte>();

            List<Byte> data_byte;

            decimal file_pos;



            if (file_name == "")

            {

                return;

            }



            // ---------------------------- Very SLOW Here ------------------------ 



            label_Status.Text = "Generating data and Writing data to file...";

            Application.DoEvents();



            FileStream fs1 = new FileStream(file_name, FileMode.OpenOrCreate,

            FileAccess.Write);

            BinaryWriter bw = new BinaryWriter(fs1);

            file_pos = 0;

            do

            {

                data_byte = RandomNumber(0, 255);

                if (file_pos + data_byte.Count <= total_file_size)

                {

                    file_data.AddRange(data_byte);

                    file_pos += data_byte.Count;

                }

                else

                {

                    if (file_pos < total_file_size)

                    {

                        file_data.AddRange(data_byte.Take((int)(total_file_size - file_pos)));

                        file_pos += total_file_size - file_pos;

                    }

                }

                bw.Write(file_data.ToArray());

                file_data.Clear();

                if( file_pos % 10 == 0 ) fnUpdate_Progress(file_pos);

            } while (file_pos <= total_file_size);



            bw.Close();

            fs1.Close();



            label_Status.Text = "File and data successfully created";



            Application.Exit();

        }





        private void comboFileSize_SelectedValueChanged(object sender, EventArgs e)

        {

            string gb_size;

            decimal gb;



            gb_size = (string)comboFileSize.SelectedItem;



            gb = Convert.ToDecimal(gb_size);



            fnCalculate_File_Size(gb);

        }

    }

}

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0
 
LVL 62

Expert Comment

by:Fernando Soto
ID: 33456986
You will need to check the limits on file size and chunk sizes used to make sure that all adds up.
0
 
LVL 6

Expert Comment

by:r3nder
ID: 33457053
try switching loops - use LINQ TakeAny();
//17%  slower for average sized collections using any()

// find implemented via LINQ

    public static bool FindViaLinq(IEnumerable<int> list, int target)

    {

        return list.Any(item => item == target);

    }

 

 

    // find implemented via standard iteration

    public static bool FindViaIteration(IEnumerable<int> list, int target)

    {

        foreach (var i in list)

        {

            if (i == target)

            {

                return true;

            }

        }

 

        return false;

    }





//90% slower using takewhile()

// Linq form

    public static int GetTargetPosition1(IEnumerable<int> list, int target)

    {

        return list.TakeWhile(item => item != target).Count();

    }

 

    // traditionally iterative form

    public static int GetTargetPosition2(IEnumerable<int> list, int target)

    {

        int count = 0;

 

        foreach (var i in list)

        {

            if(i == target)

            {

                break;

            }

 

            ++count;

        }

 

        return count;

    }

//Much faster  

// a newer method that uses linq but evaluates the count in a closure.

    public static int TakeWhileViaLinq2(IEnumerable<int> list, int target)

    {

        int count = 0;

        list.Any(item =>

            {

                if(item == target)

                {

                    return true;

                }

 

                ++count;

                return false;

            });

        return count;

    }

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0
 
LVL 10

Expert Comment

by:Najam Uddin
ID: 33462847
if your requirement is just a file of specified size, without any concern of its content, than you can use
"fsutil file createnew C:\1mbfile.txt 1000000

ie fsutil file createnew <name of file> <size in bytes>
0

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