How do I safely stop a C# .NET thread running in a Windows service?

Question

I am maintaining some code which looks something like this. It's a Windows service which does some work every 30 minutes. The ActualWorkDoneHere method takes about 30 seconds to run, but if it is stopped while running it can leave things in a bad state. What is the best way to prevent that from happening? Should I replace the While(true) with a boolean which is set to false in the onstop method (removing the thread Abort call)? Is there some way to tell if a thread is sleeping?

namespace WorkService
{
    public partial class WorkService : ServiceBase
    {
        private Thread _workerThread = null;

        public WorkService()
        {
            InitializeComponent();
        }

        protected override void OnStart(string[] args)
        {
            _workerThread = new Thread(new ThreadStart(DoWork));
            _workerThread.Start();
        }

        protected override void OnStop()
        {
            _workerThread.Abort();
        }

        static void DoWork()
        {
            int sleepMinutes = 30;

            while (true)
            {
                 ActualWorkDoneHere();

                 System.Threading.Thread.Sleep(new TimeSpan(0, sleepMinutes, 0));
            }
        }
    }
}

Answer 1

When I have something like this, I usually use a ManualResetEvent. This is set in the Stop() call. Then I wait with a timeout:

for (;;)
{
    if (_stop.WaitOne(timeout))
        break;
    DoSomething();
}