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Posted 9 Apr 2012


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Multi-threading in .NET 4

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11 Apr 2012CPOL
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.<o:p>


Before TPL we have to do thread management. But now that responsibility is taken by TPL.<o:p>

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)

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Comments and Discussions

QuestionC# Parallel.For multi thread parallel Pin
ytyet20058-Oct-14 14:30
ytyet20058-Oct-14 14:30 
QuestionMight be nice to put some timings in the output Pin
kevinbrydon11-Apr-12 23:03
kevinbrydon11-Apr-12 23:03 
QuestionWhy are you using WinAPI to get a number of processors? Pin
Laserson9-Apr-12 18:49
Laserson9-Apr-12 18:49 
AnswerRe: Why are you using WinAPI to get a number of processors? Pin
John Brett9-Apr-12 21:49
John Brett9-Apr-12 21:49 
The call is to acquire the number of the current processor, not the total number of processors.

In other words, the code is trying to illustrate that the calls are executed on different processors.

GeneralRe: Why are you using WinAPI to get a number of processors? Pin
daylightdj12-Apr-12 5:11
daylightdj12-Apr-12 5:11 

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