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Multi-threading in .NET 4

, 11 Apr 2012 CPOL
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Huge improvement on Multithreading in new Task Parallel Library for .NET 4


The purpose of this code is to demonstrate how new TPL (Task Parallel Library) of .NET 4 utilize available multi core.


Before TPL we have to do thread management. But now that responsibility is taken by TPL.

We still have to deal with data integrity (such as critical section data race and deadlock), but at least bigger part is taken from our shoulder.

The Parallel class is defined under the System.Threading.Tasks namespace and the following code demo shows the benefits of using the Parallel class if you want to use multi-threading.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Diagnostics;
using System.Runtime.InteropServices;

namespace Threads
    class Program
        [DllImport("kernel32.dll", CharSet = CharSet.Auto, SetLastError = true)]
        public static extern int GetCurrentProcessorNumber();

        private static int criticalSection = 0;
        private static object lockObject = new object();

        static void Main(string[] args)
            Console.WriteLine("==================Sequential calls==============");
            // Get the number of processor.
            int numberOfProcessors = Environment.ProcessorCount;
            for (int i = 0; i < numberOfProcessors; i++)


            Console.WriteLine("==================Parallel calls==============");
            Action action = new Action(Target);

            List<Action> parallelTaskList = new List<Action>();

            // Create equal number of task as number of processor. I hope each thread will execute in seperate processor. We will find out.
            for (int i = 0; i < numberOfProcessors; i++)




        private static void Target()
            lock (lockObject)
                Console.WriteLine(string.Format("Thread ID: {0} and Processor ID: {1} Critical Variable Value: {2}", Thread.CurrentThread.ManagedThreadId, GetCurrentProcessorNumber(), criticalSection));




This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Tony Dubey

United States United States
No Biography provided

Comments and Discussions

QuestionC# Parallel.For multi thread parallel Pinmemberytyet20058-Oct-14 15:30 
QuestionMight be nice to put some timings in the output Pinmemberkevinbrydon12-Apr-12 0:03 
QuestionWhy are you using WinAPI to get a number of processors? PinmemberLaserson9-Apr-12 19:49 
AnswerRe: Why are you using WinAPI to get a number of processors? PinmemberJohn Brett9-Apr-12 22:49 
GeneralRe: Why are you using WinAPI to get a number of processors? Pinmemberdaylightdj12-Apr-12 6:11 

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