#StackBounty: #c# #.net #memory Why does a .net program use more VirtualMemorySize64 when the computer has more ram

Bounty: 100

I’ve created a simple test application which allocates 100mb using binary arrays.

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Text;

namespace VirtualMemoryUsage
class Program
    static void Main(string[] args)
        StringBuilder sb = new StringBuilder();
        sb.AppendLine($"IsServerGC = {System.Runtime.GCSettings.IsServerGC.ToString()}");

        const int tenMegabyte = 1024 * 1024 * 10;
        long allocatedMemory = 0;
        List<byte[]> memory = new List<byte[]>();
        for (int i = 0; i < 10; i++)
            //alloc 10 mb memory
            memory.Add(new byte[tenMegabyte]);
            allocatedMemory += tenMegabyte;

        sb.AppendLine($"Allocated memory:    {PrettifyByte(allocatedMemory)}");
        sb.AppendLine($"VirtualMemorySize64: {PrettifyByte(Process.GetCurrentProcess().VirtualMemorySize64)}");
        sb.AppendLine($"PrivateMemorySize64: {PrettifyByte(Process.GetCurrentProcess().PrivateMemorySize64)}");

    private static object PrettifyByte(long allocatedMemory)
        string[] sizes = { "B", "KB", "MB", "GB", "TB" };
        int order = 0;
        while (allocatedMemory >= 1024 && order < sizes.Length - 1)
            allocatedMemory = allocatedMemory / 1024;
        return $"{allocatedMemory:0.##} {sizes[order]}";

Note: For this test it is important to set gcserver to true in the app.config

  <gcServer enabled="true"/>  

This then will show the amount of PrivateMemorySize64 and VirtualMemorySize64 allocated by the process.

While PrivateMemorySize64 remains similar on different computers, VirtualMemorySize64 varies quite a bit.
enter image description here

What is the reason for this differences in VirtualMemorySize64 when the same amount of memory is allocated? Is there any documentation about this?

Get this bounty!!!

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