[STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);

            Form1 frm = new Form1();
            Model model = new Model();
            Presenter presenter = new Presenter(frm, model);

            Application.Run(frm);
        }
...
    public partial class Form1 : Form
    {
    // Тут файл с номерами
        private string path = @"600.txt";
        public Func<string, Task> start { get; set; }
        private SynchronizationContext sctx;
        private TaskScheduler ts;

        public Form1()
        {
            InitializeComponent();
            sctx = SynchronizationContext.Current;
            ts = TaskScheduler.FromCurrentSynchronizationContext();
        }

        private async void button1_Click(object sender, EventArgs e)
        {
            await start(path).ConfigureAwait(true);

            label1.Text = "Ok";
        }

        public void SetLabel(string val)
        {
            label1.Text = val;
        }

        public void SetProgress(int mx)
        {
            progressBar1.Minimum = 0;
            progressBar1.Maximum = mx;
            progressBar1.Step = 1;
        }

        public void StepProgress()
        {
            sctx.Send(x => { progressBar1.PerformStep(); SetLabel(progressBar1.Value.ToString()); }, null);
            //progressBar1.PerformStep();
            //SetLabel(progressBar1.Value.ToString());
        }

        public TaskScheduler GetScheaduler()
        {
            return ts;
        }
    }
...
    public class Presenter
    {
        private Form1 view;
        private Model model;

        public Presenter(Form1 frm, Model mdl)
        {
            view = frm;
            model = mdl;
            model.presenter = this;
            view.start += strt;
        }

        private Task strt(string arg)
        {
            string[] lines = File.ReadAllLines(arg);
            view.SetProgress(lines.Length * 10);

            Task[] tsks = new Task[10];

            for (int i = 0; i < 10; i++)
            {
                tsks[i] = Task.Factory.StartNew(() => model.ProcessMethodAsync(lines), CancellationToken.None);
            }

            return Task.WhenAll(tsks);
        }

        public void StepProgress()
        {
            view.StepProgress();
        }
...
    public class Model
    {
        public Presenter presenter;

        public void ProcessMethodAsync(string[] lines)
        {
            foreach (var line in lines)
            {
                Task.Delay(1).Wait();
                presenter.StepProgress();
            }
        }
    }