多线程入门 多数相加的问题

Question

代码 class Program
    {
        public static Model m;
        static void Main(string[] args)
        {
            System.Diagnostics.Stopwatch stop = new System.Diagnostics.Stopwatch();
            ThreadStart ts = new ThreadStart(js);
            ThreadStart ts2 = new ThreadStart(js);
            Thread t1 = new Thread(ts);
            Thread t2 = new Thread(ts2);
            stop.Reset();
            m = new Model();
            m.i = 0;
            m.sum = 0;
            stop.Start();
            js();
            stop.Stop();
            Console.WriteLine(stop.ElapsedMilliseconds);
            Console.WriteLine(m.sum);            stop.Reset();
            m.i = 0;
            m.sum = 0; ;
            stop.Start();
            t1.Start();
            t2.Start();
            stop.Stop();
            Console.WriteLine(stop.ElapsedMilliseconds);
            Console.WriteLine(m.sum);
            Console.ReadKey();
        }        static void js()
        {
            lock (m)
            {
                for (; m.i <= 1000000000; m.i++)
                {
                    m.sum += m.i;
                }
            }
        }
    }
    class Model
    {
        public int i = 0;
        public long sum = 0;
    }结果
多线程求和出现错误的结果，我认为i是值类型 无法lock操作，导致可能相同i多次相加。所以用Model类来存储i跟sum，依旧出现错误结果。是lock这个操作没起到作用，还是其他原因。这种累加方式能否用一个方法且多线程能否实现？

Answer 1

用system.threading.interlock下的原子操作方法实现

Answer 2

        static void js()
        {
            lock (LockObj)
            {
                for (; n < 100000; n++)
                {
                    m += n;
                }
            }
        }
        public static object LockObj = new object();
        public static int m = 0, n;
        static void Main(string[] args)
        {
            System.Diagnostics.Stopwatch stop = new System.Diagnostics.Stopwatch();
            Console.WriteLine("单线程操作：");
            stop.Start();
            js();
            stop.Stop();
            Console.WriteLine("用时：" + stop.ElapsedMilliseconds);
            Console.WriteLine("值：" + m);            stop.Reset();
            m = n = 0;
            Console.WriteLine("\n\n\n\n多线程操作：");
            stop.Start();
            Thread t1 = new Thread(js);
            Thread t2 = new Thread(js);
            t1.Start();
            t2.Start();
            t1.Join();
            t2.Join();
            stop.Stop();
            Console.WriteLine("用时：" + stop.ElapsedMilliseconds);
            Console.WriteLine("值：" + m);
        }
应该像这个样子，你理解理解看。

Answer 3

锁没问题，关键是stop.Start(); 
t1.Start();
t2.Start(); 
stop.Stop();            
Console.WriteLine(stop.ElapsedMilliseconds);            
Console.WriteLine(m.sum);            
Console.ReadKey();t1，t2还没运行完你就输出了m.sum

Answer 4

学习线程同步知识
.net 4.5的：http://msdn.microsoft.com/zh-cn/library/ms173179(v=vs.110).aspx