Stringbuilder.tostring()引发异常 [英] Stringbuilder.tostring() throws exception

问题描述

你好，

我正在尝试创建一个应用程序，其中2-4个线程从不同来源获取数据
并且我必须在文本框中的表单上显示该数据.
我已经使用了一个stringbuilder，并且不断将来自不同线程的数据追加到其中.
也是一个间隔为2秒的计时器，在其滴答事件中，整个stringbuilder数据
复制到文本框.在特定长度的stringbuilder(可以说)50000之后，我将其清除.

但是有时我会遇到这种异常:

消息:索引超出范围.必须为非负数并且小于集合的大小.
参数名称:chunkLength
TargetSite:System.String ToString()

我搜索并找到了一些相对的
http://social.msdn.microsoft.com/Forums/ar/netfxbcl/thread/1051ec1c-667f-4568-a528-027cb12c34f9

但是我没有得到Textbox.Dispatcher.

现在我不确定该怎么办，也不清楚为什么会发生此异常.

代码:

Hello,

I am trying to create an application in which 2-4 threads gets data from different sources
and I have to show that data on my Form in a textbox.
I have taken a stringbuilder and i keep appending the data from different threads into it.
Also a timer with interval of 2 seconds, and on its tick event the whole stringbuilder data
is copied to the textbox. and after a particular length of stringbuilder (lets say) 50000, I clear it.

But sometimes I get this exception :

Message : Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: chunkLength
TargetSite : System.String ToString()

I have searched and found somethings relative
http://social.msdn.microsoft.com/Forums/ar/netfxbcl/thread/1051ec1c-667f-4568-a528-027cb12c34f9

But i am not getting Textbox.Dispatcher.

Now I am not sure what should I do, and also i am not clear why this exception occurs.

Code :

private void clock_Tick(object sender, EventArgs e)
 {
   try
   {
     txtMsg.Text = myClass.myStringBuilder.ToString();  //throws exception sometime
                
      if (myClass.myStringBuilder.Length == 50000)
      {
         myClass.myStringBuilder.Clear();
      }
   }
    catch (Exception ex)
    {
      //create error log
    }
 }

谢谢.

Thanks.

推荐答案

对于多线程应用程序，您需要积极采取措施来同步线程和数据访问.由于您要从多个线程添加到stringbuilder并从中读取信息，因此它可以随时处于任何状态.

试试这样的

With multi-threaded applications you need to actively take steps to synchronize your threads and data access. Since you are adding to and reading from the stringbuilder from multiple threads it could be in any state at any time.

Try something like this

public void AddString(string s)
{
  lock(this.LockObject)
  {
     StringBuilder.Add(s);
  }
} 

使用2-4个线程和线程池，很容易发现一些资源冲突.请记住，每次访问锁定您的 StringBuilder .

如果您从未使用过，请参考以下提示:
请记住，将您的锁令牌的同一实例分发给所有线程.锁令牌只是任何对象，例如:

Using 2-4 threads and thread pooling, it is easy to stumble upon some resource conflicts. Remember to lock your StringBuilder whenever you access it.

Here are some tips if you''ve never used it:
Remember to distribute the same instance of your lock-token to all threads. The lock-token is just any object, like:

object _myLockToken = new object();

您的代码将如下所示:

Your code will then be something like:

private void clock_Tick(object sender, EventArgs e)
{
  lock(_myLockToken)
  {
   try
   {
     txtMsg.Text = myClass.myStringBuilder.ToString();  //throws exception sometime
                
      if (myClass.myStringBuilder.Length == 50000)
      {
         myClass.myStringBuilder.Clear();
      }
   }
    catch (Exception ex)
    {
      //create error log
    }
  }
}

锁定声明(C#参考)

我非常有信心这会有所帮助.
(在更新GUI时，请记住BeginInvoke模式)

lock Statement (C# Reference)

I''m quite confident that this will help.
(Remember the BeginInvoke-pattern when updating the GUI)

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