Parallel Programming in C# 4.0 using Visual Studio 2010

Framework in Visual Studio 2010 has been more enhanced and visual studio IDE itself have got overhauled a bit. Well, I’m not going to give you a list of ALL features – it’s been blogged already around the world. Better Google it or Bing it with “VS2010+Features”

However, few notable features that caught my eyes are “Parallel Programming”, “F# – Functional Programming”, “Velocity – Distributed Caching”, “Azure Tools” and more important of all the evolving Team system.

But I first wanted to dirt my hand with Parallel Computing, because if you are a computer science student – well, you would be more excited about this than others.
Remember the big pillow sized books that we used to read to make this work? Well, things have changed and world have shrunk already. Though I cannot explain all the nitty gritty of parallel programming I will try this to explain in LAY MAN Terms.

Well, during the Stone Age [!] – Most of the computers in the world had only ONE Processors, except those big beasty servers which are always locked up in rooms with high security (well, usually *nix or Solaris servers) – these beasty servers used to manage most of the corporations. These servers had multiple processors and it took huge efforts to write software’s and manage them.

Welcome to the modern world – Every household and every laptop being sold these days at least have two or more processors.

Now – that has posed us a BIG Question? Hardwares have evolved, but has our software evolved to execute on multiple processors? – The answer is NO. At least not in the mainstream programming world – let’s say for example what would happen

1. If we execute a simple FOR Loop
2. That would call a service (that takes a longer time)
3. … and execute sequentially for N Times

On a single processor this is acceptable and we might use threads to increase the efficiency.

Is this still acceptable on a multiple processors? The answer is no. Fine, but how do we get efficiency without the hurdles of running and managing too many threads? Shouldn’t there be an easier way out for this?

Alrighty, without much ado, let me show you how easy(!) this is and a little insight on what happens behind the scenes. Let’s churn out a quick code here based on the same questions we have. Let us say a real long process (Well it could be about counting the stars in the UniverseJ, huh) and let us say you want to do this N times.

In our quest to count all the stars in the universe, let’s first create a data structure for the star and add to the universe, and let us use the good ol` mother of all loops the “FOR” Loop, and see how much inefficient this loop has become these modern days!!

“The Sequential execution took almost 30 seconds in my Dual Core Computer.”

And here is the Parallel Computing version of the same method. Yes, the for loop has been replaced with Parallel.For a new entry in System.Threading namespace.
How simpler can this get to?

VOILA! The Parallel execution took Just 3 Seconds in my Dual Core Computer.

Well, That’s a significant performance improvement without Hardware Scale-out or Scale-up, all we are doing is using the existing hardware resource efficiently. So much to a FOR Loop J, Huh. 30 Seconds of execution have become 3 seconds instantly. Look closer to the screenshot – the stars are not counted sequentially, instead it allocates the task to the available CPU in parallel.

Because the loop is run in parallel, each iteration is scheduled and run individually on whatever core is available. This means that the list is not necessarily processed in order, which can drastically impact your code. You should design your code so that each iteration of the loop is completely independent from the others. Any single iteration should not rely on another in order to complete correctly.

Let us catch up more on the insights soon on next part of the same series…

source : http://aditiblogs.com/blog/blog/2009/06/07/parallel-programming-in-c-40-using-visual-studio-2010/