Question

Consider the code below. I do not want to create multiple instances of class Waiter. (So I cannot use ManualResetEvent class)

using System;
using System.Threading;

    public class Waiter
    {
        static int counter=0;
        static int max=20;

        public void Start()
        {
            for (int i = 1; i <= max; i++)
            {
                ThreadPool.QueueUserWorkItem(DoWork, (object)i);

            }
            Console.Read();//without this line the application quits before all threads are complete :(

        }

        public void DoWork(object o)
        {
            try
            {
                Thread.Sleep(1000);

            }
            finally
            {
                counter++;
                Console.WriteLine(counter);
                if (counter==max )
                {
                    Console.WriteLine("All threads complete");
                }
            }



        }

    }

    public class ThreadPoolExample
    {
        static void Main()
        {

            Waiter wtr=new Waiter();
            wtr.Start();



        }
    }

I have two problems with the above code

1>Without the Console.Read() the application quits before all threads end.

2>The statement Console.WriteLine("All threads complete"); executes twice.

How do I fix this?

Answer 1

Use Tasks instead, and then you can do Task.WaitAll(tasks);

Also, instantiate your tasks through the factory:

Task.Factory.StartNew(() => { Console.Writeline(""); });

It will use the thread pool for you.