新线程启动时C＃表单挂起

Question

I created new thread and start it !
When new thread is running, Winform is hanging(freezing)
Why winform hangs ?
I want WinForm to move freely when I start a new thread
how to do it ?
(I will not use thread pool here.)

        private void button4_Click(object sender, EventArgs e)
        {
            Thread t1 = new Thread(new ThreadStart(delegate ()
            {
                Run();
            }));
            t1.Start();
            t1.Join();
            MessageBox.Show("Complete");
        }

        private void Run()
        {
            int a = 1;
            for (int i = 1; i <= 999999999; i++)
            {
                ++a;
            }
        }

Answer 1

Read the documentation about Join .

Blocks the calling thread until the thread represented by this instance terminates.

So, you start the thread, and then you Join, which means, that your UI thread will block and wait for the thread to finish.

You could do async/await :

private async void button4_Click(object sender, EventArgs e)
{
    await Task.Run(Run);
    MessageBox.Show("Complete");
}