Question

I’m creating app which uses very large amount of memory. When I finish computation the program remains with high memory as I can notice in Task Manager.

How to reset RAM memory usage of my program?

I’m creating a large array in which I store MB worth of random characters. Then print all characters into a variable and then write the content of the variable to the file.

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.TrimExcess();
        }
    }
}

Answer 1

There is little you can do about this. The memory consumed by unused object gets freed when garbage collection happens. And you can not force garbage collection. You can read more about it on MSDN also check GC Class

Example from MSDN

private const long maxGarbage = 1000;

static void Main()
{
    MyGCCollectClass myGCCol = new MyGCCollectClass();

    // Determine the maximum number of generations the system
    // garbage collector currently supports.
    Console.WriteLine("The highest generation is {0}", GC.MaxGeneration);

    myGCCol.MakeSomeGarbage();

    // Determine which generation myGCCol object is stored in.
    Console.WriteLine("Generation: {0}", GC.GetGeneration(myGCCol));

    // Determine the best available approximation of the number 
    // of bytes currently allocated in managed memory.
    Console.WriteLine("Total Memory: {0}", GC.GetTotalMemory(false));

    // Perform a collection of generation 0 only.
    GC.Collect(0);

    // Determine which generation myGCCol object is stored in.
    Console.WriteLine("Generation: {0}", GC.GetGeneration(myGCCol));

    Console.WriteLine("Total Memory: {0}", GC.GetTotalMemory(false));

    // Perform a collection of all generations up to and including 2.
    GC.Collect(2);

    // Determine which generation myGCCol object is stored in.
    Console.WriteLine("Generation: {0}", GC.GetGeneration(myGCCol));
    Console.WriteLine("Total Memory: {0}", GC.GetTotalMemory(false));
    Console.Read();
}

void MakeSomeGarbage()
{
    Version vt;
    for(int i = 0; i < maxGarbage; i++)
    {
       // Create objects and release them to fill up memory
       // with unused objects.
       vt = new Version();
    }
}