C＃线程/锁定混乱 [英] C# Threading/Lock confusion

问题描述

我有以下代码：

var items = new List<string> {"1", "2", "3"}; // 200 items
foreach(var item in items) {
  ThreadPool.QueueUserWorkItem((DoWork), item);
}

private void DoWork(object obj)
{
  lock(this)
  {
    using(var sw = File.AppendText(@"C:\somepath.txt")
    {
      sw.WriteLine(obj);
    }
  }
}

由于螺纹的，由于某种原因，我得到写出到文件中的200个项目的一个随机数。60，或127，或有时只3.如果我删除线程池，只是写原来的foreach循环内，所有200个项目被成功写入。

Because of the threading, for some reason, I get a random number of the 200 items written out to the file. 60 or 127 or sometimes only 3. If I remove the ThreadPool and just write inside the original foreach loop, all 200 items are written successfully.

不知道为什么出现这种情况？

Not sure why this occurs?

感谢您的帮助。

推荐答案

从的MSDN关于线程池 文档说明了一切：

The following note from MSDN documentation on ThreadPool says it all:

在托管线程池中的线程是后台线程，也就是说，它们的的IsBackground 属性是真实的。这意味着线程池线程不会让应用程序运行的所有前台线程都退出后，

The threads in the managed thread pool are background threads. That is, their IsBackground properties are true. This means that a ThreadPool thread will not keep an application running after all foreground threads have exited.

您的应用程序只需（由达主的结尾）你的线程之前完成运行退出。

Your application simply exits (by reaching end of Main) before your threads finish running.

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