Beginner's Guide to Threading in .NET: Part 3 of n

using System;
using System.Threading;
using System.Collections.Generic;

namespace ReaderWriterLockSlimTest
{

    /// <summary>
    /// This simple class demonstrates the usage a Reader/Writer 
    /// situation, using the ReaderWriterLockSlim class
    /// </summary>
    class Program
    {

        static ReaderWriterLockSlim rw = new ReaderWriterLockSlim();
        static List<int> items = new List<int>();
        static Random rand = new Random();

        static void Main(string[] args)
        {
            //start some readers
            new Thread(Read).Start("R1");
            new Thread(Read).Start("R2");
            new Thread(Read).Start("R3");

            //start some writers
            new Thread(Write).Start("W1");
            new Thread(Write).Start("W2");

        }


        static void Read(object threadID)
        {
            //do read
            while (true)
            {
                try
                {
                    rw.EnterReadLock();
                    Console.WriteLine("Thread " + threadID +
                        " reading common source");
                    foreach (int i in items)
                        Thread.Sleep(10);
                }
                finally
                {
                    rw.ExitReadLock();
                }
            }
        }


        static void Write(object threadID)
        {
            //do write
            while (true)
            {
                int newNumber = GetRandom(100);
                try
                {
                    rw.EnterWriteLock();
                    items.Add(newNumber);
                }
                finally
                {
                    rw.ExitWriteLock();
                    Console.WriteLine("Thread " + threadID +
                        " added " + newNumber);
                    Thread.Sleep(100);
                }
            }
        }

        static int GetRandom(int max)
        {
            //lock on the Random object
            lock (rand)
                return rand.Next(max);
        }
    }
}