How to start a stopped thread

Question

I create a new thread and start it from a main thread.

m_MyThread = new Thread(HandleMyThread);
m_MyThread.IsBackground = true;
m_MyThread.Start();

private void HandleMyThread()
{
    while (true)
    {
        Thread.Sleep(5000);
        return;
    }
}

After 5 seconds, this thread will finish and its ThreadState is Stopped. I want to start it again when user clicks on button but I get a ThreadStateException (Thread is running or terminated; it cannot restart):

private void button1_Click(object sender, EventArgs e)
{
    m_MyThread.Start(); // ->raise exception
}

Please help me how to restart a stopped thread. Thanks.

Answer 1

I know this question is a bit old, but I thought I would post a response in case others come here.

For this example code, if it were changed to look like this:

Thread m_MyThread;
private void HandleMyThread()
{
    while (true)
    {
        Thread.Sleep(5000);
        return;
    }
}

private void button1_Click(object sender, EventArgs e)
{
    if (!m_MyThread.IsAlive)
    {
        m_MyThread = new Thread(HandleMyThread);
        m_MyThread.IsBackground = true;
        m_MyThread.Start();
    }
}

This would create a new instance of the thread and start it. The ThreadStateException error is because, simply, you can't re-start a thread that's in a stopped state. m_MyThread.Start() is only valid for threads in the Unstarted state. What needs done in cases like this is to create a new thread instance and invoke Start() on the new instance.

Answer 2

Use a ManualResetEvent, and instead of Thread.Sleep, wait for the event with a timeout.

Then, any other thread can activate the event, and immediately resume the sleeping thread.

Once a thread is exited, it can no longer run. So don't let it exit. Instead, put it back to sleep waiting for an event.