Parallel Tasks in .NET 4.0 – Methods that Return value

For methods that return a value, you would need to use the Task(TResult) class which represents an asynchronous operation that can return a value. We will explore how to use this class in this article.

For Example:


using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Threading;
using System.Threading.Tasks;

namespace URLRoutingDemoApp.Parallel_For
{
public partial class ParallelInvokeWithReturnValue : System.Web.UI.Page
{
static string stValues = string.Empty;
string strTaskResult = string.Empty;
string strTaskResult1 = string.Empty;
protected void Page_Load(object sender, EventArgs e)
{
stValues = "";
strTaskResult = "";
strTaskResult1 = "";
//Two Approaches
//Approach 1-> First Initialize the task and then execute
Task Task Task
Task1.Start();
Task2.Start();
Task3.Start();

strTaskResult += "Task1=" + Task1.Result.ToString() + "</br>";
strTaskResult += "Task1=" + Task2.Result.ToString() + "</br>";
strTaskResult += "Task1=" + Task3.Result.ToString() + "</br>";

lblparallelInvokewithreturnvalue.Text = stValues + "::::</br>" + strTaskResult;

//Approach 2-> Initialize and execute task at the same time
stValues = "";
var TaskApp1=Task var TaskApp2 = Task var TaskApp3 = Task
strTaskResult1 += "Task1=" + TaskApp1.Result.ToString() + "</br>";
strTaskResult1 += "Task1=" + TaskApp2.Result.ToString() + "</br>";
strTaskResult1 += "Task1=" + TaskApp3.Result.ToString() + "</br>";

lblparallelInvokewithreturnvalue1.Text = stValues + "::::</br>" + strTaskResult1;
}

static int GenerateNumbers()
{
int i;
for (i = 0; i < 10; i++)
{
stValues += "Method1 - Number " + i.ToString() + " </br>";
Thread.Sleep(1000);
}
return i;
}

static string PrintCharacters()
{
string str = "blog";
for (int i = 0; i < str.Length; i++)
{
stValues += "Method2 - Character " + str[i].ToString() + " </br>";
Thread.Sleep(1000);
}
return str;
}

static int PrintArray()
{
int[] arr = { 1, 2, 3, 4, 5, 6, 7, 8 };
foreach (int i in arr)
{
stValues += "Method3 - Array " + i.ToString() + " </br>";
Thread.Sleep(1000);
}
return arr.Count();
}
}
}

Used the Task(TResult) class to call methods that returned a value.

Parallel Tasks in .NET 4.0

In .NET 4.0, 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.

For Example:
using System.Threading;
using System.Threading.Tasks;

public partial class ParallelInvoke : System.Web.UI.Page
{
static string stValues = string.Empty;

protected void Page_Load(object sender, EventArgs e)
{
stValues = "";
Parallel.Invoke(new Action(GenerateNumbers), new Action(PrintCharacters), new Action(PrintArray));
parallelInvokelbl.Text = stValues;
}

static void GenerateNumbers()
{
for (int i = 0; i < 10; i++)
{
stValues += "Method1 - Number " + i.ToString() + "
";
Thread.Sleep(1000);
}
}

static void PrintCharacters()
{
string str = "blog";
for (int i = 0; i < str.Length; i++)
{
stValues += "Method2 - Character " + str[i].ToString() + "
";
Thread.Sleep(1000);
}

}

static void PrintArray()
{
int[] arr = { 1, 2, 3, 4, 5, 6, 7, 8 };
foreach (int i in arr)
{
stValues += "Method3 - Array " + i.ToString() + "
";
Thread.Sleep(1000);
}
}
}