Why does Thread.Sleep() freeze the Form?

Question

I try to experiment with Thread.Sleep(). I created basic Windows Forms application with one button.

    private void button1_Click(object sender, Ev         


        

Answer 1

Thread.Sleep just sleeps the current thread (i.e. stops it from doing anything, such as redrawing, processing clicks etc), which in your case is the UI thread. If you put the Sleep in DoStuff you wouldn't experience the block as you'd be on a separate thread although you wouldn't be able to update button1. Depending on the version of .NET you're using consider using the Task Parallel Library, something like this:

private TaskScheduler _uiScheduler;
public Form1()
{
    InitializeComponent();
    _uiScheduler = TaskScheduler.FromCurrentSynchronizationContext();
}

private void button1_Click(object sender, EventArgs e)
{

    Thread thread1 = new Thread(DoStuff);
    thread1.Start();

    // Create a task on a new thread.
    Task.Factory.StartNew(() =>
        {
            for (int i = 0; i < 100000; i++)
            {
                Thread.Sleep(500);

                // Create a new task on the UI thread to update the button
                Task.Factory.StartNew(() =>
                    { button1.Text += "."; }, CancellationToken.None, TaskCreationOptions.None, _uiScheduler);
            }
        });
}