Generics vs Object performance

I'm doing practice problems from MCTS Exam 70-536 Microsft .Net Framework Application Dev Foundation, and one of the problems is to create two classes, one generic, one object type that both perform the same thing; in which a loop uses the class and iterated over thousand times. And using the timer, time the performance of both. There was another post at C# generics question that seeks the same questoion but nonone replied.

Basically if in my code I run the generic class first it takes loger to process. If I run the object class first than the object class takes longer to process. The whole idea was to prove that generics perform faster.

I used the original users code to save me some time. I didn't particularly see anything wrong with the code and was puzzled by the outcome. Can some one explain why the unusual results?

Thanks,

Risho

Here is the code:

class Program
{
    class Object_Sample
    {            
        public Object_Sample()
        {
            Console.WriteLine("Object_Sample Class");
        }

        public long getTicks()
        {
            return DateTime.Now.Ticks;
        }

        public void display(Object a)
        {
            Console.WriteLine("{0}", a);
        }
    }

    class Generics_Samle<T>
    {            
        public Generics_Samle()
        {
            Console.WriteLine("Generics_Sample Class");
        }

        public long getTicks()
        {
            return DateTime.Now.Ticks;
        }

        public void display(T a)
        {
            Console.WriteLine("{0}", a);
        }
    }

    static void Main(string[] args)
    {            
        long ticks_initial, ticks_final, diff_generics, diff_object;
        Object_Sample OS = new Object_Sample();
        Generics_Samle<int> GS = new Generics_Samle<int>();

        //Generic Sample
        ticks_initial = 0;
        ticks_final = 0;
        ticks_initial = GS.getTicks();

        for (int i = 0; i < 50000; i++)
        {
            GS.display(i);
        }
        ticks_final = GS.getTicks();
        diff_generics = ticks_final - ticks_initial;

        //Object Sample
        ticks_initial = 0;
        ticks_final = 0;
        ticks_initial = OS.getTicks();

        for (int j = 0; j < 50000; j++)
        {
            OS.display(j);
        }

        ticks_final = OS.getTicks();
        diff_object = ticks_final - ticks_initial;

        Console.WriteLine("\nPerformance of Generics {0}", diff_generics);
        Console.WriteLine("Performance of Object {0}", diff_object);

        Console.ReadKey();
    }
}

Well, the first problem I can see is that you're using the DateTime object to measure time in your application (for a very small interval).

You should be using the Stopwatch class. It offers better precision when trying to benchmark code.

The second problem is that you're not allowing for JIT (Just-In-Time compilation). The first call to your code is going to take longer simply because it has to be JIT'd. After that, you'll get your results.

I would make a single call in to your code before you start timing things so you can get an accurate idea of what is happening during the loop.

You should run both classes a separate time before timing it to allow the JITter to run.

Your test is incorrect. Here are your methods:

public void display(T a)
{
    Console.WriteLine("{0}", a); // Console.WriteLine(string format, params object[] args) <- boxing is performed here
}

public void display(Object a)// <- boxing is performed here
{
    Console.WriteLine("{0}", a); 
}

So, in both cases you are using boxing. Much better would be if your class, for example, will count total sum of values, like:

public void add(long a)
{
    Total += a;
}

public void display(Object a)// <- boxing is performed here
{
    Total += (long) a;// <- unboxing is performed here
}

1. Your timed code includes a Console.WriteLine(). That will take up 99.999999% of the time.
2. Your assumption that generic will be faster in this situation is wrong. You may have misinterpreted a remark about non-generic collection classes.
3. This won't be on he exam.

why would it be faster? both ints must be boxed in order to use Console.WriteLine(string, object)

edit: ToString() itself does not seem to cause boxing http://weblogs.asp.net/ngur/archive/2003/12/16/43856.aspx

so when you use Console.WriteLine(a); which would call Console.WriteLine(Int32) that should work i guess (i would need to look into reflector to confirm this)