C# Code profiling

Introduction

Video games programmer have always the same objective : write fastest code as possible. There's no need to use assembly everywhere or know MSIL by heart, just use a profiler and see ;p Loop is something very usefull and very used in C# but what is the best solution for an ArrayList to browse all items ? Is IEnumerator faster than for () ? Bets are opened. For this article, I've chosen Red Gate Ants Profiler 2.6.0 Build 62 (http://www.red-gate.com/products/ants_profiler/index.htm). Results are... suprising.

ArrayList

I've found 4 ways to browse an ArrayList and Antony another one :

static public void Browse1 (ArrayList list)
{
 int Total = 0;
 for (int i = 0; i < list.Count; i++)
  {
   Total += (int)list[i];
  }
}

static public void Browse2 (ArrayList list)
{
 int Total = 0;
 int Count = list.Count;
 for (int i = 0; i < Count; i++)
 {
  Total += (int)list[i];
 }
}

static public void Browse3 (ArrayList list)
{
 int Total = 0;
 IEnumerator Iterator = list.GetEnumerator (); 
 while (Iterator.MoveNext ())
 {
  Total += (int)Iterator.Current;
 }
}

static public void Browse4 (ArrayList list)
{
 int Total = 0;
 foreach (int i in list)
 {
  Total += i;
 }
}

static public void Browse5(ArrayList list)
{
 int Total = 0;
 for (int i = list.Count - 1; i >= 0; i--)
 {
  Total += (int)list[i];
 }
}

In Main(), just fill the ArrayList :

ArrayList MyList = new ArrayList ();

// Add items
DateTime CurrentTime = DateTime.Now;
Random rand = new Random (CurrentTime.Millisecond);
int Count = (int)(CurrentTime.Ticks % (1<<25));
int NewValue = (rand.Next () % 100);

Console.WriteLine ("Fill list with {0} elements", Count);
for (int i = 0; i < Count; i++)
{
    MyList.Add (NewValue);
}

// Browse
DateTime d1, d2, d3, d4, d5, d6;
d1 = DateTime.Now;
Console.WriteLine ("Browse1");
Browse1 (MyList);
d2 = DateTime.Now;
Console.WriteLine ("Browse2");
Browse2 (MyList);
d3 = DateTime.Now;
Console.WriteLine ("Browse3");
Browse3 (MyList);
d4 = DateTime.Now;
Console.WriteLine ("Browse4");
Browse4 (MyList);
d5 = DateTime.Now;
Console.WriteLine("Browse5");
Browse5(MyList);
d6 = DateTime.Now;

// Print results
TimeSpan r1,r2,r3,r4,r5;
r1 = d2 - d1;
r2 = d3 - d2;
r3 = d4 - d3;
r4 = d5 - d4;
r5 = d6 - d5;

Console.WriteLine("Browse1 : {0}", r1.TotalMilliseconds);
Console.WriteLine("Browse2 : {0}", r2.TotalMilliseconds);
Console.WriteLine("Browse3 : {0}", r3.TotalMilliseconds);
Console.WriteLine("Browse4 : {0}", r4.TotalMilliseconds);
Console.WriteLine("Browse5 : {0}", r5.TotalMilliseconds);

Console.WriteLine("Press any key");
Console.ReadKey();

Here are the results (Release Version, PIV C, XP Pro SP2) :

Something interesting is in first case, both, Solution 3 & 4 have the same time but not the second one.

Method 2 or 5 seems to be the fastest but not always in the same order.

We can do other tests on other computers:

- Retry with Red Gate Ants Profiler and not only on timer

- Look physical memory allocation to avoid hard disk swap

- Test on virtual machine

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