Question

What I want to do is to write a program that can generate large files (1GB and up) filled with nothing less than random junk.

The problem is that if I try to create a file larger than 100MB my app uses more than 500MB Ram and takes for ever.

Steps I’m using:

• use loop to generate junk data and add it to character array.
• store all characters from the array to the variable.
• save the data from variable to the file.

Is there any better solution for this? Maybe some shortcut?

This is what I’m working with:

namespace Fake_File_Creator
{
    public partial class MainWindow : Form
    {
        private string text;
        private List<char> stringChars;

        public MainWindow()
        {
            InitializeComponent();
        }

        private void btnNewFile_Click(object sender, EventArgs e)
        {
            sfdNewFile.Filter = "All Files|*.*";

            if (sfdNewFile.ShowDialog() == DialogResult.OK)
            {
                lblMessage.Text = "Generating data...";
                bwCreateData.RunWorkerAsync((int)nudSize.Value * 1024000);
            }
        }

        private void bwCreateData_DoWork(object sender, DoWorkEventArgs e)
        {
            var random = new Random();
            var chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz 0123456789 ~!@#$%^&*()_+ /.,'[];{}|:<>?";

            stringChars = new List<char>();

            for (int i = 0; i < (int)e.Argument; i++)
            {
                stringChars.Add(chars[random.Next(chars.Length)]);
            }

            text = new string(stringChars.ToArray());
        }

        void bwCreateData_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            lblMessage.Text = "Saving file...";
            bwCreateFile.RunWorkerAsync();
        }

        private void bwCreateFile_DoWork(object sender, DoWorkEventArgs e)
        {
            using (StreamWriter outfile = new StreamWriter(sfdNewFile.FileName))
            {
                outfile.Write(text);
            }
        }

        void bwCreateFile_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            lblMessage.Text = "File succesfully created...";

            text = string.Empty;
            stringChars.Clear();
            stringChars = null;
            GC.Collect(); 
        }
    }
}

Answer 1

Just write a ton of data to the file directly rather than saving to memory in the string “text”.

You can call outfile.Write(“junk text”) in a loop.