Task Parallel Library

Task Parallel Library is use to concurrently execute multiple task, method, many class functions

it include within namespace

 using System.Threading;

using System.Threading.Tasks;

In .NET 4.5, we have a set of new API's to simplify the process of adding parallelism and concurrency to applications. This set of API's is called the "Task Parallel Library (TPL)" and is located in the System.Threading and System.Threading.Tasks namespaces.

The Parallel class found in the System.Threading.Tasks namespace “provides library-based data parallel replacements for common operations such as for loops, for each loops, and execution of a set of statements”. In this article, we will use the  Invoke method of the Parallel class to call multiple methods, possibly in parallel.

Update: Also check the following articles:

Parallel Tasks in .NET 4.0 (Part II) – Methods that Return value

Cancelling Tasks in .NET 4.0

Parallel.For Method in .NET 4.0 vs the C# For Loop

Follow these steps:

Step 1: Open VS 2010 > File > New Project > Choose ‘Windows’ from the Installed Templates list > Console Application. Give a name to your project and choose a location to save the project.

Step 2: Add the following namespaces

C#

using System.Threading;

using System.Threading.Tasks;

 

VB.NET

Imports System.Threading

Imports System.Threading.Tasks

Now write the following three methods which will possibly be called concurrently using Parallel.Invoke()

C#

static void GenerateNumbers()

{

    for (int i = 0; i < 10; i++)

    {

        Console.WriteLine("Method1 - Number: {0}", i);

        Thread.Sleep(1000);

    }

}

 

static void PrintCharacters()

{

    string str = "dotnetcurry";

    for (int i = 0; i < str.Length; i++)

    {

        Console.WriteLine("Method2 - Character: {0}", str[i]);

        Thread.Sleep(1000);

    }

 

}

 

static void PrintArray()

{

    int[] arr = {1, 2, 3, 4, 5, 6, 7, 8 };

    foreach (int i in arr)

    {

        Console.WriteLine("Method3 - Array: {0}", i);

        Thread.Sleep(1000);

    }

}

 

VB.NET

Shared Sub GenerateNumbers()

      For i As Integer = 0 To 9

            Console.WriteLine("Method1 - Number: {0}", i)

            Thread.Sleep(1000)

      Next i

End Sub

 

Shared Sub PrintCharacters()

      Dim str As String = "dotnetcurry"

      For i As Integer = 0 To str.Length - 1

            Console.WriteLine("Method2 - Character: {0}", str.Chars(i))

            Thread.Sleep(1000)

      Next i

 

End Sub

 

Shared Sub PrintArray()

      Dim arr() As Integer = {1, 2, 3, 4, 5, 6, 7, 8 }

      For Each i As Integer In arr

            Console.WriteLine("Method3 - Array: {0}", i)

            Thread.Sleep(1000)

      Next i

End Sub

 

Step 3: In order to call these 3 methods concurrently, we will use Parallel.Invoke() as shown below:

C#

static void Main(string[] args)

{

    Parallel.Invoke(

        new Action(GenerateNumbers),

        new Action(PrintCharacters),

        new Action(PrintArray)

        );

 

    Console.ReadLine();

}

 

VB.NET

Shared Sub Main(ByVal args() As String)

      Parallel.Invoke(New Action(AddressOf GenerateNumbers), New Action(AddressOfPrintCharacters), New Action(AddressOf PrintArray))

 

      Console.ReadLine()

End Sub

Observe how these methods are being called, in parallel

In this article, we used Parallel.Invoke() to call methods that did not return a value. For methods that return a value, you would need to use the Task class which we will explore in one of the forthcoming articles. [Update: Also check the next part of this article Parallel Tasks in .NET 4.0 (Part II) – Methods that Return value  and Cancelling Tasks in .NET 4.0 and

Parallel.For Method in .NET 4.0 vs the C# For Loop ].

The entire source code of this article can be downloaded over here. I hope you liked the article and I thank you for viewing it.