ArrayList的.NET并行​​处理 [英] .NET parallel processing of ArrayList

问题描述

我试图在嵌入多线程的第一次运行到一些意想不到的问题，希望能帮到你。

I am attempting at embedding multi-threading for the first time ever and running into some unexpected issues, hope you can help.

这里的code片段，让我的烦恼：

Here's the code fragment that gives me troubles:

ArrayList recordsCollection = new ArrayList();
ArrayList batchCollection = null;
int idx = 0;

while(true)
{
  // Some code to generate and assign new batchCollection here
  recordsCollection.Add(batchCollection);

  ThreadPool.QueueUserWorkItem(delegate
  {
    ProcessCollection(recordsCollection.GetRange(idx, 1));
  });
  Interlocked.Increment(ref idx);
}

private void ProcessCollection(ArrayList collection)
{
   // Do some work on collection here
}

在过程收集方法被调用，我试图遍历集合我得到基础列表中的范围是无效的。

Once the Process Collection method is invoked and I am attempting to iterate through collection I am getting "The range in the underlying list is invalid".

在此先感谢！

更新：伙计们，谢谢你们每一个人。通过将你的建议，我是能够大大简化，并得到它的工作。

Update: Guys, thank you to each and every one of you. Through applying your suggestions I was able to greatly simplify and get it to work.

推荐答案

您有几个问题。

• 在像马克指出，你在拍摄这将真的在这里混淆事物的循环变量。
• 您正在修改的集合，而在同一时间阅读它，而无需使用同步机制。

我假设你已经省略了code，用于获取 batchCollection ，然后定期从删除它们 recordsCollection 为简便起见，否则就不会有问题有作为。

I am assuming you have omitted the code for acquiring a batchCollection and then periodically removing them from recordsCollection for brevity, otherwise there would be issues there as well.

下面是如何修复它。

ArrayList recordsCollection = new ArrayList();  
ArrayList batchCollection = null;  
int idx = 0;  

while(true)  
{  
  lock (recordsCollection) 
  {
    recordsCollection.Add(batchCollection);  
  }

  int capturedIndex = idx; // Used for proper capturing.

  ThreadPool.QueueUserWorkItem(delegate  
  {
    ArrayList range;
    lock (recordsCollection)
    {
      range = recordsCollection.GetRange(capturedIndex, 1);
    }
    ProcessCollection(range);  
  });  

  idx++;
}  

还是我重构版本里面，尽我所能告诉反正，做同样的事情...

Or my refactored version which, as best I can tell anyway, does the exact same thing...

List<List<Record>> recordsCollection = new ArrayList();  
List<Record> batchCollection = null;  

while(true)  
{  
  recordsCollection.Add(batchCollection);

  List<List<Record>> range = new List<List<Record>>();
  range.Add(batchCollection);

  ThreadPool.QueueUserWorkItem(delegate  
  {
    ProcessCollection(range);  
  });      
}  

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