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) :

Count	24 145 243	18 491 373
Browse1	327.55 ms	249.56 ms
Browse2	233.96 ms	202.77 ms
Browse3	717.48 ms	545.91 ms
Browse4	717.48 ms	561.51 ms
Browse5	249.56 ms	171.57 ms

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