Using BackgroundWorker

I’ve decided to take a deeper look at all available multi-threading options in .net 4.5. One of the simpler options is the BackgroundWorker. To investigate, I’ve setup a simple BackgroundWorker with progress and completion reporting.

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

namespace TestBackgroundWorker
{
    class TestBkGrdWorker
    {
        static void LogMsg(string msg, params object[] args)
        {
            Console.Out.Write("{0} ThreadId={1} ",
                DateTime.Now.ToString("HH:MM:ss.fff"),
                Thread.CurrentThread.ManagedThreadId);
            Console.Out.WriteLine(msg, args);
        }


        // RunTest
        //
        // Function run by main thread
        // Main thread sets up the background worker instance
        // and fires it off

        public void RunTest()
        {
            BackgroundWorker bkWorker = new BackgroundWorker();
            bkWorker.WorkerReportsProgress = true;

            // setup functions the background worker calls
            // to do work, report progress, and to report completion
            bkWorker.DoWork += bkWorker_DoWork;
            bkWorker.ProgressChanged += bkWorker_ProgressChanged;
            bkWorker.RunWorkerCompleted += bkWorker_RunWorkerCompleted;

            AutoResetEvent myFlag = new AutoResetEvent(false);

            // trigger background worker to run async
            bkWorker.RunWorkerAsync(myFlag);

            LogMsg("Main thread working, BackgroundWorker busy={0}",
                bkWorker.IsBusy);
            myFlag.WaitOne();       // wait for someone to signal this flag

            LogMsg("RunTest thread resumes control upon completion of background thread");
        }


        // bkWorker_ProgressChanged
        //
        // Report progress

        void bkWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            LogMsg("Background worker update progress, {0:00.0}% done",
                e.ProgressPercentage);
        }

        // bkWorker_RunWorkerCompleted
        //
        // Report work is completed

        void bkWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            LogMsg("Background worker completed");
        }


        // bkWorker_DoWork
        //
        // Function run by background worker.
        // Random work method that takes an arbitrarily set 2 seconds
        // to complete, with a progress report every 200ms.

        void bkWorker_DoWork(object sender, DoWorkEventArgs e)
        {
            LogMsg("Background worker starting");
            float percentDone = 0.0f;
            for (int i = 0; i < 10; i++)
            {
                Thread.Sleep(200);
                percentDone += 10.0f;
                BackgroundWorker bkwkr = sender as BackgroundWorker;
                if (bkwkr != null)
                {
                    bkwkr.ReportProgress((int)percentDone);
                }
            }
            LogMsg("Background worker completed");

            AutoResetEvent myFlag = e.Argument as AutoResetEvent;
            if (myFlag != null)
            {
                myFlag.Set();
            }
        }



        // Main
        // Start up a background worker test instance

        static void Main(string[] args)
        {
            TestBkGrdWorker testWkr = new TestBkGrdWorker();
            testWkr.RunTest();
        }
    }
}

The output:

18:05:51.835 ThreadId=3 Background worker starting
18:05:51.805 ThreadId=1 Main thread working, BackgroundWorker busy=True
18:05:52.107 ThreadId=4 Background worker update progress, 10.0% done
18:05:52.287 ThreadId=4 Background worker update progress, 20.0% done
18:05:52.487 ThreadId=4 Background worker update progress, 30.0% done
18:05:52.687 ThreadId=4 Background worker update progress, 40.0% done
18:05:52.889 ThreadId=4 Background worker update progress, 50.0% done
18:05:53.091 ThreadId=4 Background worker update progress, 60.0% done
18:05:53.291 ThreadId=4 Background worker update progress, 70.0% done
18:05:53.493 ThreadId=4 Background worker update progress, 80.0% done
18:05:53.693 ThreadId=4 Background worker update progress, 90.0% done
18:05:53.893 ThreadId=4 Background worker update progress, 100.0% done
18:05:53.893 ThreadId=3 Background worker completed
18:05:53.903 ThreadId=1 RunTest thread resumes control upon completion of background thread