簡單多線程 非安全實例 與 解決方法

多線程 非安全實例

 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
namespace ThreadSample
{
    class Program
    {
        static void Main(string[] args)
        {
            int numThreads = 20;
            ShareState state = new ShareState();
            Thread[] threads = new Thread[numThreads];
            for (int i = 0; i < numThreads; i++)
            {
                threads[i] = new Thread(new Task(state).DoTheTask);
                threads[i].Start();
            }
            for (int i = 0; i < numThreads; i++)
            {
              threads[i].Join();  
            }
            Console.WriteLine("ShareState.State最後結果是:" + state.State);
            Console.ReadLine();
        }
    }
    public class Task
    {
        ShareState shareState;
        public Task(ShareState shareState)
        {
            this.shareState = shareState;
        }
        public void DoTheTask()
        {
            ///設爲5000，數據大點更能 看到線程非安全的效果
            for (int i = 0; i < 5000; i++)
            {
                shareState.State += 1;
            }
        }
    }
    public class ShareState
    {
        public int State { get; set; }
    }

}

 

解決方法的實例

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;

namespace ThreadSample02
{
    class Program
    {
        static void Main(string[] args)
        {
            int numThreads = 20;
            ShareState state = new ShareState();
            Thread[] threads = new Thread[numThreads];
            for (int i = 0; i < numThreads; i++)
            {
                threads[i] = new Thread(new Task(state).DoTheTask);
                threads[i].Start();
            }
            for (int i = 0; i < numThreads; i++)
            {
                threads[i].Join();
            }
            Console.WriteLine("ShareState.State最後結果是:" + state.State);
            Console.ReadLine();
        }
    }
    public class Task
    {
        ShareState shareState;
        public Task(ShareState shareState)
        {
            this.shareState = shareState;
        }
        public void DoTheTask()
        {
            ///設爲5000，數據大點更能 看到線程非安全的效果
            for (int i = 0; i < 5000; i++)
            {
                lock (shareState)
                {
                    shareState.State += 1;
                }
            }
        }
    }
    public class ShareState
    {
        public int State { get; set; }
    }
}