using System;

using System.Collections.Concurrent;

using System.Collections.Generic;

using System.Linq;

using System.Threading;

using System.Threading.Tasks;

public class Program

{

    public static void Main()

    {

        // 目標資料筆數

        int tartgetCount = 10000;

        List<string> list = new List<string>();

        Console.WriteLine("預期List有 {0} 筆資料", tartgetCount);

​

        // Exception

        ConcurrentQueue<Exception> exceptions = new ConcurrentQueue<Exception>();

        // 可能會有Race condition，list的資料筆數可能不會跟目標相同

        Parallel.For(0, tartgetCount, (i, loopState) =>

        {

            try

            {

                // 新增隨機字串到List

                list.Add(new Random().NextDouble().ToString());

            }

            catch (IndexOutOfRangeException e)

            {

                // 因為List不是Thread-Safe，也可能會有索引超出範圍的錯誤

                exceptions.Enqueue(e);

            }

        });

​

        if (!exceptions.IsEmpty)

        {

            Console.WriteLine(exceptions.First().ToString());

        }

        else

        {

            Console.WriteLine("實際List有 {0} 筆資料(沒有用Lock): ", list.Count());

        }

        // 解法1: 把物件加到集合內時，使用Lock

        list = new List<string>();

        Object _lock = new Object();

​

        Parallel.For(0, tartgetCount, (i, loopState) =>

        {

            lock (_lock)

            {

                list.Add(new Random().NextDouble().ToString());

            }

        });

​

        Console.WriteLine("實際List有 {0} 筆資料(有用Lock): ", list.Count());

​

        // 解法2: 集合改用Concurrent(Threa-Safe的集合類別)

        ConcurrentBag<string> stack = new ConcurrentBag<string>();

​

        Parallel.For(0, tartgetCount, (i, loopState) =>

        {

            stack.Add(new Random().NextDouble().ToString());

        });

​

        Console.WriteLine("實際Stack有 {0} 筆資料: ", stack.Count());

​

    }

}