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How do I run a simple bit of code in a new thread?

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How do I start a new thread in C#?

Programming threads in C# To create a new thread, you should leverage the ThreadStart delegate and pass the reference to a method that should execute on the thread. Note that a delegate is a type-safe function pointer. The following code snippet shows how you can create a new thread object using this delegate.

How might you ensure that only one thread at a time executes a particular method?

Yes, you can use lock for this. Create a private synchronization object in your class, acquire the lock on this object and only one thread at a time will be able to execute the code within the lock block.

Does Async create a new thread?

The async and await keywords don't cause additional threads to be created. Async methods don't require multithreading because an async method doesn't run on its own thread. The method runs on the current synchronization context and uses time on the thread only when the method is active.


Good place to start reading is Joe Albahari.

If you want to create your own thread, this is as simple as it gets:

using System.Threading;
new Thread(() => 
{
    Thread.CurrentThread.IsBackground = true; 
    /* run your code here */ 
    Console.WriteLine("Hello, world"); 
}).Start();

BackgroundWorker seems to be best choice for you.

Here is my minimal example. After you click on the button the background worker will begin working in background thread and also report its progress simultaneously. It will also report after the work completes.

using System.ComponentModel;
...
    private void button1_Click(object sender, EventArgs e)
    {
        BackgroundWorker bw = new BackgroundWorker();

        // this allows our worker to report progress during work
        bw.WorkerReportsProgress = true;

        // what to do in the background thread
        bw.DoWork += new DoWorkEventHandler(
        delegate(object o, DoWorkEventArgs args)
        {
            BackgroundWorker b = o as BackgroundWorker;

            // do some simple processing for 10 seconds
            for (int i = 1; i <= 10; i++)
            {
                // report the progress in percent
                b.ReportProgress(i * 10);
                Thread.Sleep(1000);
            }

        });

        // what to do when progress changed (update the progress bar for example)
        bw.ProgressChanged += new ProgressChangedEventHandler(
        delegate(object o, ProgressChangedEventArgs args)
        {
            label1.Text = string.Format("{0}% Completed", args.ProgressPercentage);
        });

        // what to do when worker completes its task (notify the user)
        bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(
        delegate(object o, RunWorkerCompletedEventArgs args)
        {
            label1.Text = "Finished!";
        });

        bw.RunWorkerAsync();
    }

Note:

  • I put everything in single method using C#'s anonymous method for simplicity but you can always pull them out to different methods.
  • It is safe to update GUI within ProgressChanged or RunWorkerCompleted handlers. However, updating GUI from DoWork will cause InvalidOperationException.

The ThreadPool.QueueUserWorkItem is pretty ideal for something simple. The only caveat is accessing a control from the other thread.

System.Threading.ThreadPool.QueueUserWorkItem(delegate {
    DoSomethingThatDoesntInvolveAControl();
}, null);

Quick and dirty, but it will work:

Using at top:

using System.Threading;

simple code:

static void Main( string[] args )
{
    Thread t = new Thread( NewThread );
    t.Start();
}

static void NewThread()
{
    //code goes here
}

I just threw this into a new console application for an exmaple


Here is another option:

Task.Run(()=>{
//Here is a new thread
});