C#多线程学习-求和

1、代码如下

// ***********************************************************************
// Assembly         : Share.Code.MultiThreadTest
// Author           : zhujinrong
// Created          : 11-20-2014
//
// Last Modified By : zhujinrong
// Last Modified On : 11-20-2014
// ***********************************************************************
// <copyright file="SumMultiThread2.cs" company="Microsoft">
//     Copyright (c) Microsoft. All rights reserved.
// </copyright>
// <summary></summary>
// ***********************************************************************

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

namespace Share.Code.MultiThreadTest
{
    /// <summary>
    /// 多线程求和
    /// </summary>
    public class SumMultiThread2
    {

/// <summary>
/// 锁
/// </summary>
static object lockObj = new object();

        /// <summary>
        /// 子线程数量
        /// </summary>
        private int threadNum = 0;

        /// <summary>
        /// 待处理数据
        /// </summary>
        private List<int> dataList = new List<int>();

        /// <summary>
        /// 通知一个线程或多个线程正在发生的事情
        /// </summary>
        private List<ManualResetEvent> manualEventList = new List<ManualResetEvent>();

        /// <summary>
        /// 自动重置同步事件数组 
        /// </summary>
        private AutoResetEvent[] autoEvents;

        /// <summary>
        ///  初始化同步事件
        /// </summary>
        private List<AutoResetEvent> tempEvents = new List<AutoResetEvent>();

        /// <summary>
        /// 手动重置同步事件 
        /// </summary>
        private ManualResetEvent manualEvent;

        /// <summary>
        /// 子线程结果
        /// </summary>
        private List<long> subSumList = new List<long>();

        /// <summary>
        /// 子线程结果
        /// </summary>
        private Dictionary<int, long> resultList = new Dictionary<int, long>();

        /// <summary>
        /// 构造函数
        /// </summary>
        /// <param name="dataList">数据</param>
        /// <param name="threadNum">线程个数</param>
        public SumMultiThread2(List<int> dataList, int threadNum)
        {
            this.dataList = dataList;
            this.threadNum = threadNum;
            for (int i = 0; i < this.threadNum; i++)
            {
                this.tempEvents.Add(new AutoResetEvent(false));
            }

            this.autoEvents = this.tempEvents.ToArray();
            this.manualEvent = new ManualResetEvent(false);
        }

        /// <summary>
        /// 执行结果
        /// </summary>
        public long Result
        {
            get;
            private set;
        }

        /// <summary>
        /// 执行
        /// </summary>
        public void Execute()
        {
            if (this.dataList == null || this.dataList.Count == 0 || this.threadNum == 0)
            {
                return;
            }

            ThreadPool.QueueUserWorkItem(new WaitCallback(this.SetManualEvent));

            // 给每个线程分配数据
            List<List<int>> list = new List<List<int>>();
            for (int i = 0; i < this.threadNum; i++)
            {
                list.Add(new List<int>());
            }

            for (int i = 0; i < this.dataList.Count; i++)
            {
                list[i % this.threadNum].Add(this.dataList[i]);
            }

            for (int i = 0; i < this.threadNum; i++)
            {
                Dictionary<int, List<int>> dic = new Dictionary<int, List<int>>();
                dic.Add(i, list[i]);
                ThreadPool.QueueUserWorkItem(new WaitCallback(this.ExecuteSum), dic);
            }

            // 等待所有自动事件终止 
            WaitHandle.WaitAll(this.autoEvents);
            long sum = 0;
            foreach (var item in this.resultList)
            {
                sum += item.Value;
            }

            this.Result = sum;
        }

        /// <summary>
        /// 具体执行
        /// </summary>
        /// <param name="obj">对象</param>
        private void ExecuteSum(object obj)
        {
            DateTime start = DateTime.Now;
            DateTime end = DateTime.Now;
            Dictionary<int, List<int>> dic = obj as Dictionary<int, List<int>>;
            int index = 0;
            foreach (var item in dic)
            {
                index = item.Key;
                long sum = 0;
                if (item.Value != null && item.Value.Count > 0)
                {
                    foreach (var temp in item.Value)
                    {
                        sum += temp;
                    }
                }

               // this.subSumList.Add(sum);

lock (lockObj)
{
this.resultList.Add(index, sum);
}

            }

            end = DateTime.Now;
            Console.WriteLine("线程" + index + "执行完毕,耗时" + ((TimeSpan)(end - start)).TotalMilliseconds);
            this.autoEvents[index].Set();
        }

        /// <summary>
        /// 重置手动事件为终止状态 
        /// </summary>
        /// <param name="obj">obj</param>
        private void SetManualEvent(object obj)
        {
            ////重置手动事件为终止状态 
            this.manualEvent.Set();
        }
    }
}

2、测试

 public static void Test2()
        {
            List<int> list = new List<int>();

            for (int i = 0; i < 1000000; i++)
            {
                list.Add(i);
            }

            DateTime start = DateTime.Now;
            DateTime end = DateTime.Now;
            long sum = 0;
            for (int i = 0; i < list.Count; i++)
            {
                sum += list[i];
            }

            end = DateTime.Now;
            Console.WriteLine("主线程结果:" + sum + ",耗时:" + ((TimeSpan)(end - start)).TotalMilliseconds);

            start = DateTime.Now;
            SumMultiThread2 thread = new SumMultiThread2(list, 10);
            thread.Execute();
            end = DateTime.Now;
            Console.WriteLine("多线程结果是:" + thread.Result + ",耗时:" + ((TimeSpan)(end - start)).TotalMilliseconds);

            Console.Read();
        }

3、注意数据分配

 

注意list 本身是线程不安全的，要加锁才能达到目的。谢谢 楼下的 一叶知秋 帮忙发现的问题。