JafTalks

Software Developers phobia is code optimization, how to write faster codes? How to make programs runs faster at the same hardware? How to make your client happy?

Heaving read a few million lines of C# code, I came up with these optimization benchmarks that help to significantly improve code performance through simple changes.

1. Boxing and unboxing

static private void TestBoxingAndUnboxing() {
int i = 123;
object o = i; // Implicit boxing
i = 456; // Change the contents of i
int j = (int)o; // Unboxing (may throw an exception if the types are incompatible)
}

//this function is about 2*Log(N) faster
static private void TestNoBoxingAndUnboxing()
{
int i = 123;
i = 456; // Change the contents of i
int j = i; // Compatible types
}

2. Collections

//Using actual size for data rather than some default size increases performance up to 50%
ht = new Hashtable(count); // Creates an Hashtable using size = Count LoadData(ht, count);
// Display results
Display.Show(1, "Elapsed time: " + t.ElapsedTime.ToString() + " ms \n", 0);
// End of the demo
Display.Show(-1, "Collections demo end.\n", 1);
}

static private void LoadData(Hashtable ht, int Count)
{
// Fill the employee collection with data
for (int i = 0; i < Count; i++)
{
Employee employee = new Employee(i, "Employee" + i.ToString());
ht.Add(i, employee);
}

3. Exceptions

//throwing and catching an exception is 1000 slower than checking for an error code
static void FunctionThatThrows()
{
throw new Exception();
}
static int FunctionThatReturnsErrorCode()
{
return -1;
}

4. Loops

//for loop is twice faster than foreach loop
static private void TestForeachLoop(ArrayList List)
{
int id = 0;
foreach (int i in List)
{
// Do something with the object ...
id = i;
}
}
static private void TestForLoop(ArrayList List)
{
int id = 0;
int count = List.Count;
for (int i = 0; i < List.Count; i++)
{
// Do something with the object ...
id = (int)List[i];
}
}

5. Garbage collection

//80% slower than doing nothing
static private void Test(int count)
{
DisposableObject []obj = new DisposableObject[count];
for(int i=0;i<count;i++)
obj[i]=new DisposableObject();
// Do some work with the object here ...
// Release the object.
obj = null;
// Forcing garbage collection to finalize the object.
Collect();
// Wait for the GC's Finalize thread to finish.
WaitForPendingFinalizers();
}
//150% slower than doing nothing
static private void TestDispose(int count)
{
DisposableObject []obj = new DisposableObject[count];
for(int i=0;i<count;i++)
obj[i]=new DisposableObject();
// Do some work with the object here ...
// Release the object.
for(int i=0;i<count;i++)
obj[i].Dispose();
obj = null;
// Forcing garbage collection to finalize the object.
Collect();
// Wait for the GC's Finalize thread to finish.
WaitForPendingFinalizers();
}
//best solution
static private voide LetDotnetCleanup(in
t count)
{
// Start performance timing
t.Start();
int count=int.Parse(args[0]);
DisposableObject []obj = new DisposableObject[count];
for(int i=0;i<count;i++)
obj[i]=new DisposableObject();
// Do some work with the object here ...
// Release the object.
obj = null;
t.Stop();
// Stop performance timing
}

Reference http://msdn.microsoft.com/en-us/library/ms973858.aspx