c# - Shutting down a multithreaded application

Question

I'm trying to write a ThreadManager for my C# application. I create several threads:
One thread for my text writer.
One thread that monitors some statistics.
Multiple threads to perform a large sequence of calculations (up to 4 threads per core and I run my app on a 2x quad core server).

My application normally runs for up to 24 hours at a time, so all the threads get created in the beginning and they persist through the entire time the app runs.

I want to have a single place where I "register" all of my treads and when the application is shutting down I simply invoke a method and it goes through all of the registered threads and shuts them down.

For that purpose I have devised the following class:

public class ThreadManager
{
    private static Object _sync = new Object();
    private static ThreadManager _instance = null;
    private static List<Thread> _threads;
    private ThreadManager()
    {
        _threads = new List<Thread>();
    }

    public static ThreadManager Instance
    {
        get
        {
            lock (_sync)
            {
                if (_instance == null)
                {
                    _instance = new ThreadManager();
                }
            }
            return _instance;
        }
    }

    public void AddThread(Thread t)
    {
        lock (_sync)
        {
            _threads.Add(t);
        }
    }

    public void Shutdown()
    {
        lock (_sync)
        {
            foreach (Thread t in _threads)
            {
                t.Abort(); // does this also abort threads that are currently blocking?
            }
        }
    }
}

I want to ensure that all of my threads are killed so the application can close properly and shutting down in the middle of some computation is just fine too. Should I be aware of anything here? Is this approach good given my situation?

Answer 1

If you set the threads to background threads, they will be killed when the application is shut down.

myThread.IsBackground = true;

obviously if you need the threads to finish before shutdown, this is not the solution you want.