项目到了最后关头遭遇瓶颈，多线程操作Hashtable时出错，请求各位高手帮助！！

Question

项目中有块实时监控的内容，大概意思是一个线程负责把符合条件的值保存到Hashtable中，另一个线程不断的从这个Hashtable中读取数据，在这个过程中俩个线程同时操作Hashtable会报错误，从网上找了好多资料都没有解决，请各位高手帮忙！
下面是运行时会错的代码，请各位高手在次代码上进行修改：
using System;
using System.Collections;
using System.Threading;
using System.Collections.Generic;
using System.Text;namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            test t = new test();
            t.Start();
        }
    }
    public class test
    {
        Hashtable hs = new Hashtable();
        Thread thHsAdd = null;
        Thread thHsWrite = null;
        int index = 0;
        public void Start()
        {
            thHsAdd = new Thread(new ThreadStart(this.HsAdd));
            thHsAdd.Start();
            thHsWrite = new Thread(new ThreadStart(this.HsWrite));
            thHsWrite.Start();
        }
        public void HsAdd()
        {
            while (true)
            {
                hs.Add(index, DateTime.Now.ToString());
                index++;
                Thread.Sleep(1000);
            }
        }
        public void HsWrite()
        {
            while (true)
            {
                IDictionaryEnumerator ie = hs.GetEnumerator();
                while (ie.MoveNext())
                {
                    Console.WriteLine("key={0},value={1}", ie.Key, ie.Value);
                    Thread.Sleep(1000);
                }
            }
        }
    }
}

Answer 1

lock试试,write也lock        public void HsAdd() {
            lock (hs) {
                while (true) {
                    hs.Add(index, DateTime.Now.ToString());
                    index++;
                    Thread.Sleep(1000);
                }
            }
        }

Answer 2

to:xiaoqhuang
按照你的样子加入了lock，但在HsWrite里读取时还是报错误。to：lovefootball 
在什么地方使用lock？

Answer 3

你HsWrite里有加lock吗?
        public void HsWrite()
        {
           lock (hs) {
             while (true)
             {
                IDictionaryEnumerator ie = hs.GetEnumerator();
                while (ie.MoveNext())
                {
                    Console.WriteLine("key={0},value={1}", ie.Key, ie.Value);
                    Thread.Sleep(1000);
                }
             }
          }
        }

Answer 4

to ：xiaoqhuang 
这样会导致部分数据加不到Hashtable里，还有其他的办法吗？

Answer 5

http://msdn2.microsoft.com/zh-cn/library/system.collections.hashtable.synchronized(VS.80).aspx

Answer 6

to:whycom 
这个方法试过了，偶尔也会报错误

Answer 7

to:whycom   
这个方法试过了，偶尔也会报错误
====
能保证只有一个线程在写吗？

Answer 8

//枚举中不能再写的，这样改就对了。
using System;
using System.Collections;
using System.Threading;
using System.Collections.Generic;
using System.Text;namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            test t = new test();
            t.Start();
        }
    }
    public class test
    {
        Hashtable hs = new Hashtable();
        Thread thHsAdd = null;
        Thread thHsWrite = null;
        int index = 0;
        public void Start()
        {
            thHsAdd = new Thread(new ThreadStart(this.HsAdd));
            thHsAdd.Start();
            thHsWrite = new Thread(new ThreadStart(this.HsWrite));
            thHsWrite.Start();
        }
        public void HsAdd()
        {
            while (true)
            {
                lock (hs)
                {
                    hs.Add(index, DateTime.Now.ToString());
                }
                index++;
                Thread.Sleep(1000);
            }
        }
        public void HsWrite()
        {
            while (true)
            {
                lock (hs)
                {
                    IDictionaryEnumerator ie = hs.GetEnumerator();
                    ie.MoveNext();
                        Console.WriteLine("key={0},value={1}", ie.Key, ie.Value);
                }
                Thread.Sleep(1000);
            }
        }
    }
}

Answer 9

感谢大家，问题解决了，原理是在读取HASTABLE时不要直接读取它，而是读取它的一个副本，经过多次测试没有报错，呵呵
using System;
using System.Collections;
using System.Threading;
using System.Collections.Generic;
using System.Text;namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            test t = new test();
            t.Start();
        }
    }
    public class test
    {
        Hashtable hs = new Hashtable();
        Thread thHsAdd = null;
        Thread thHsWrite = null;
        Thread thHsDel = null;
        int index = 0;
        public void Start()
        {
            thHsAdd = new Thread(new ThreadStart(this.HsAdd));
            thHsAdd.Start();
            thHsWrite = new Thread(new ThreadStart(this.HsWrite));
            thHsWrite.Start();
            thHsDel = new Thread(new ThreadStart(this.HsDel));
            thHsDel.Start();
        }
        public void HsAdd()
        {                while (true)
                {
                    lock (hs.SyncRoot)
                    {
                        hs.Add(index, DateTime.Now.ToString());
                    }
                    index++;
                    Thread.Sleep(10);
                }
        }
        public void HsWrite()
        {
            Hashtable tp = null;
            while (true)
            {
                tp = (Hashtable)hs.Clone();
                IDictionaryEnumerator ie = tp.GetEnumerator();
                while (ie.MoveNext())
                {
                    Console.WriteLine("key={0},value={1}", ie.Key, ie.Value);
                    Thread.Sleep(100);
                }
            }
        }
        public void HsDel()
        {
            Hashtable tp = null;
            while (true)
            {
                tp = (Hashtable)hs.Clone();
                IDictionaryEnumerator ie = tp.GetEnumerator();
                while (ie.MoveNext())
                {
                    if (ie.Key.ToString().IndexOf("0") > -1)
                    {
                        lock (hs.SyncRoot)
                        {
                            hs.Remove(ie.Key);
                        }
                        Console.WriteLine("--------------------------------已删除对象{0}------------------------------" ,ie.Key);
                    }
                   Thread.Sleep(10); //必须加，有效降低CPU占有率
                }
            }
        }
    }
}

Answer 10

还有你用枚举方式读取hashtable 会有问题，因为读的过程中 写入数据会破坏hashtalbe枚举机制
给你改了一下程序using System;
using System.Collections;
using System.Threading;
using System.Collections.Generic;
using System.Text;namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            test t = new test();
            t.Start();
        }
    }
    public class test
    {
        Hashtable hs;
        Hashtable hsSync;
        public test()
        {
            hs = new Hashtable();
            hsSync = Hashtable.Synchronized(hs);
        }
        
        Thread thHsAdd = null;
        Thread thHsWrite = null;
        int index = 0;
        public void Start()
        {
            thHsAdd = new Thread(new ThreadStart(this.HsAdd));
            thHsAdd.Start();
            thHsWrite = new Thread(new ThreadStart(this.HsWrite));
            thHsWrite.Start();
        }
        public void HsAdd()
        {
            while (true)
            {
                lock (hsSync)
                {
                    hsSync.Add(index, DateTime.Now.ToString());
                    index++;
                    Thread.Sleep(1000);
                }
            }
        }
        public void HsWrite()
        {
            while (true)
            {
                int nCount = hsSync.Keys.Count;
                for (int i = 0; i < nCount; i++) 
                {
                    Console.WriteLine( i.ToString() + hsSync[i].ToString());
                }
                Console.WriteLine("------------------------------------");
            }
        }
    }
}

Answer 11

        public void HsWrite()
        {
            Hashtable tp = null;
            while (true)
            {
                tp = (Hashtable)hs.Clone();
                IDictionaryEnumerator ie = tp.GetEnumerator();
                while (ie.MoveNext())
                {
                    Console.WriteLine("key={0},value={1}", ie.Key, ie.Value);
                    Thread.Sleep(100);
                }
            }
        }
注意检查一下这段代码，可能使你的程序：  每次读hashtable时间间隔越来越长(100*hashtable成员个数 ms)，这样写的程序结果是很奇怪和不可控的。

Answer 12

用信号量控制肯定没有问题
using System;
using System.Collections;
using System.Threading;
using System.Collections.Generic;
using System.Text;namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            test t = new test();
            t.Start();
        }
    }
    
    public class test
    {
        System.Threading.ManualResetEvent obj = new ManualResetEvent(false);
        Hashtable hs = new Hashtable();
        Thread thHsAdd = null;
        Thread thHsWrite = null;
        int index = 0;
        public void Start()
        {
            thHsAdd = new Thread(new ThreadStart(this.HsAdd));
            thHsAdd.Start();
            thHsWrite = new Thread(new ThreadStart(this.HsWrite));
            thHsWrite.Start();
        }
        public void HsAdd()
        {            while (true)
            {
                if (obj.WaitOne(10, false) == true)
                {
                    hs.Add(index, DateTime.Now.ToString());
                    index++;
                }
                Thread.Sleep(1000);
            }
        }
        public void HsWrite()
        {
            while (true)
            {
                obj.Reset();
                IDictionaryEnumerator ie = hs.GetEnumerator();
                while (ie.MoveNext())
                {
                    Console.WriteLine("key={0},value={1}", ie.Key, ie.Value);
                    
                }
                obj.Set();
                Thread.Sleep(1000);
            }
        }
    }
}

Answer 13

非常感谢你的新方法，我测试过了，上面的代码偶而也会出错，如果同时不只俩个线程来访问hastable的话，这可方法也会报错，比如：using System;
using System.Collections;
using System.Threading;
using System.Collections.Generic;
using System.Text;namespace ConsoleApplication1
{
    class Program1
    {
        static void Main(string[] args)
        {
            test1 t = new test1();
            t.Start();
        }
    }    public class test1
    {
        System.Threading.ManualResetEvent obj = new ManualResetEvent(false);
        Hashtable hs = new Hashtable();
        Thread thHsAdd = null;
        Thread thHsWrite = null;
        Thread thHsDel = null;
        int index = 0;
        public void Start()
        {
            thHsAdd = new Thread(new ThreadStart(this.HsAdd));
            thHsAdd.Start();
            thHsWrite = new Thread(new ThreadStart(this.HsWrite));
            thHsWrite.Start();
            thHsDel = new Thread(new ThreadStart(this.HsDel));
            thHsDel.Start();
        }
        public void HsAdd()
        {            while (true)
            {
                if (obj.WaitOne(10,false) == true)
                {
                    hs.Add(index, DateTime.Now.ToString());
                    index++;
                }
                Thread.Sleep(10);
            }
        }
        public void HsWrite()
        {
            while (true)
            {
                obj.Reset();
                IDictionaryEnumerator ie = hs.GetEnumerator();
                while (ie.MoveNext())
                {
                    Console.WriteLine("key={0},value={1}", ie.Key, ie.Value);
                }
                obj.Set();
                Thread.Sleep(10);
            }
        }
        public void HsDel()
        {
            while (true)
            {
                obj.Reset();
                IDictionaryEnumerator ie = hs.GetEnumerator();
                while (ie.MoveNext())
                {
                    if (ie.Key.ToString().IndexOf("0") > -1)
                    {
                        //lock (hs)
                        //{
                        //    hs.Remove(ie.Key);
                        //}
                        Console.WriteLine("--------------------------------已删除对象{0}------------------------------", ie.Key);
                    }
                }
                obj.Set();
                Thread.Sleep(10);
            }
        }
    }
}