Thread Pooling in C# – BackgroundWorker

The BackgroundWorker class allows you to run an operation on a separate, dedicated thread. Time-consuming operations, such as calling third party API/service, downloads and database transactions, can cause your user interface to stop responding. You should use BackgroundWorkder when you want a responsive user interface and you must perform time-consuming operations.

using System;
using System.ComponentModel;
using System.Threading;

namespace TestConsole
{
    class Program
    {
        public static void Main(string[] args)
        {
           var backgroundWorker = new BackgroundWorker
                                      {
                                          WorkerReportsProgress = true,
                                          WorkerSupportsCancellation = true
                                      };
            backgroundWorker.DoWork += new DoWorkEventHandler(DoLongWork);
            backgroundWorker.ProgressChanged += new ProgressChangedEventHandler(
                ProgressChanged);
            backgroundWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(
                OperationCompleted);
            backgroundWorker.RunWorkerAsync();  //Start worker thread

            //You can comment/uncomment below two lines and see what happens
            Thread.Sleep(3000);
            //Cancel worker thread even if it has not completed
            backgroundWorker.CancelAsync();   

            Console.WriteLine("Main thread ends");
            Console.ReadKey();
        }

        public static void DoLongWork(object sender, DoWorkEventArgs e)
        {
            var worker = sender as BackgroundWorker;
            Console.WriteLine("Operation has started");
            for (var i = 1; i <= 5; i++)
            {
                //Cancel operation in between if requested
                if ((worker.CancellationPending == true)) 
                {
                    Console.WriteLine("Operation has been cancelled in between");
                    e.Cancel = true;
                    break;
                }
                // Perform a time consuming operation and report progress.
                Thread.Sleep(1000);
                //Report current progress so that it can be updated on UI
                worker.ReportProgress((i * 20));  
            }
            Console.WriteLine("End of DoLongWork method");
        }

        public static void ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            //Update progress on UI
            Console.WriteLine("Operation has completed {0}%", e.ProgressPercentage);
        }

        public static void OperationCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            Console.WriteLine(
                "Operation has either completed successfully or has been cancelled");
        }
    }
}

I have provided rich comments in the program so that it would be easy for you to understand how BackgroundWorker works. You can also learn more about BackgroundWorker by commenting/uncommenting some lines and see their impact. For example: If you could comment line which sets WorkerReportProgress = true; and see if progress is reported, i.e., updateProgress method is called or not.