Footprints of Private and Shared Memories

C# Tutorials - Herong's Tutorial Examples

∟Footprints of Private and Shared Memories

This section provides a tutorial example on how to estimate footprints of private memory and shared memory of C# applications.

In order to get a better understanding of private memory and virtual memory usages, I wrote another tutorial example program called, MemoryIncreased.cs, to see changes on memory usages when more private data is requested.

// MemoryIncreased.cs
// Copyright (c) 2010 HerongYang.com. All Rights Reserved.

using System;
public class MemoryIncreased {
   public static void Main() {
      long[][] list;
      list = GetMegaBytes(1024);
   }
   public static long[][] GetMegaBytes(long max) {
      long[][] list = new long[max][];
      Console.WriteLine("Memory Usage: Data/Private/Virtual/WS");
      for (int n=0; n<max; n++) {
         PrintUsage(n);
         list[n] = new long[1024*128];
      }
      return list;
   }
   public static void PrintUsage(long n) {
      System.Diagnostics.Process proc
         = System.Diagnostics.Process.GetCurrentProcess();
      Console.Write("{0} / ", n*1024*1024);
      Console.Write("{0} / ", proc.PrivateMemorySize64);
      Console.Write("{0} / ", proc.VirtualMemorySize64);
      Console.Write("{0} / ", proc.WorkingSet64);
      Console.WriteLine();
   }
}

I compiled it with .NET 4 C# compiler and got this output:

C:\herong>\windows\Microsoft.NET\Framework\v4.0.30319\csc
   MemoryIncreased.cs

C:\herong>MemoryIncreased.exe

Memory Usage: #/Data/Private/Virtual/WS
   0 /          0 /    8753152 /   89227264 /   5799936 /
   1 /    1048576 /   10072064 /   89227264 /   6225920 /
   2 /    2097152 /   11448320 /   89227264 /   6508544 /
   3 /    3145728 /   12627968 /   89227264 /   6774784 /
   4 /    4194304 /   13807616 /   89227264 /   6909952 /
   5 /    5242880 /   14987264 /   89227264 /   7049216 /
   6 /    6291456 /   16035840 /   89227264 /   7065600 /
   7 /    7340032 /   17215488 /   89227264 /   7204864 /
   8 /    8388608 /   18395136 /   89227264 /   7344128 /
   9 /    9437184 /   19574784 /   89227264 /   7479296 /
  10 /   10485760 /   20885504 /   89227264 /   7757824 /
  11 /   11534336 /   22196224 /   89227264 /   8032256 /
  12 /   12582912 /   23506944 /   89227264 /   8323072 /
  13 /   13631488 /   24883200 /   89227264 /   8605696 /
  14 /   14680064 /   26193920 /   89227264 /   8888320 /
  15 /   15728640 /   28790784 /  107249664 /   9216000 /
  16 /   16777216 /   30101504 /  107249664 /   9502720 /
  17 /   17825792 /   30756864 /  106594304 /  10043392 /
  18 /   18874368 /   31936512 /  106594304 /  10182656 /
  19 /   19922944 /   33116160 /  106594304 /  10317824 /
  20 /   20971520 /   34295808 /  106594304 /  10457088 /
  21 /   22020096 /   35475456 /  106594304 /  10592256 /
  22 /   23068672 /   36655104 /  106594304 /  10731520 /
  23 /   24117248 /   37834752 /  106594304 /  10870784 /
  24 /   25165824 /   39014400 /  106594304 /  11005952 /
  25 /   26214400 /   40062976 /  106594304 /  11059200 /
  26 /   27262976 /   41111552 /  106594304 /  11063296 /
  27 /   28311552 /   42160128 /  106594304 /  11071488 /
  28 /   29360128 /   43208704 /  106594304 /  11075584 /
  29 /   30408704 /   46858240 /  125796352 /  11239424 /
  30 /   31457280 /   48037888 /  125796352 /  11374592 /
...
1014 / 1063256064 / 1228591104 / 1300529152 / 147308544 /
1015 / 1064304640 / 1229770752 / 1300529152 / 147447808 /
1016 / 1065353216 / 1230950400 / 1300529152 / 147603456 /
1017 / 1066401792 / 1232130048 / 1300529152 / 147738624 /
1018 / 1067450368 / 1233350656 / 1317306368 / 147886080 /
1019 / 1068498944 / 1234530304 / 1317306368 / 148021248 /
1020 / 1069547520 / 1235709952 / 1317306368 / 148160512 /
1021 / 1070596096 / 1236889600 / 1317306368 / 148295680 /
1022 / 1071644672 / 1238069248 / 1317306368 / 148434944 /
1023 / 1072693248 / 1239248896 / 1317306368 / 148574208 /

The output shows that:

The private memory increased linearly most of the time. This tells us that private memory is the private portion of virtual memory actually being used by the application data.
Looking at private memory at step 0, we can assume that the private memory footprint of a C# application is about 8,753,152 bytes.
The virtual memory increased in steps each time a new 1-MB array was allocated. This tells us that virtual memory is the sum of private memory, shared memory and free memory.
Looking at virtual memories at step 14 and 15, we can assume that virtual memory, 89,227,264 bytes, was fully used (no more free memory) when private memory reached 26,193,920 bytes. Based on this, we can assume that shared memory footprint of a C# application is about 89,227,264 - 26,193,920 = 63,033,344 (bytes).
If above calculations are accurate, the total memory footprint of a C# application is about 8,753,152 + 63,033,344 = 71,786,496 (bytes).