c#多线程程序与WebRequest

本文关键字：WebRequest 程序 多线程 | 更新日期: 2023-09-27 18:18:49

首先，我是论坛的新手，所以请对我和我的英语有一点耐心。: -)

我正在写一个c#应用程序，它应该发送多线程SOAP请求到apache后端。到目前为止，一切都很好，但我遇到了一个问题。应用程序首先读取一个XML文件从另一个系统，首先解析成类，排序并发送到SOAP后端。下面是代码片段

List<Thread> ThreadsPerOneRecord = new List<Thread>();         
bool ExecuteSingleThreaded = false;
//The variable list is passed as parameter to the function 
foreach (Record prov in list)
{
  XMLResult.AppendText("Type: " + prov.Type + Environment.NewLine);
  Thread t = new Thread(() => Send(prov, c));                                
  t.Start();
  //Here the sleep 
  Thread.Sleep(50);
  ThreadsPerOneRecord.Add(t);               
  #region Code for test single threaded execution
  if (ExecuteSingleThreaded)
  {
    foreach (Thread t2 in ThreadsPerOneRecord)
      t2.Join();
    ThreadsPerOneRecord.Clear();
  }
  #endregion
}
XMLResult.AppendText("Waiting for the threads to finish" + Environment.NewLine);
//Waiting for the threads to finish
foreach (Thread t in ThreadsPerOneRecord)            
  t.Join();

当我将此发送到SOAP web服务时，除了一个请求外，它工作得很好。这些请求彼此混淆在一起。例如:

What it should be: 
Record 1 -> SOAP
Record 2 -> SOAP
Record 3 -> SOAP
What it is
Record 1 -> SOAP
Record 2 -> SOAP 
Record 2 -> SOAP 
Record 3 -> nowhere

我已经尝试调试整个代码，并与调试器它工作良好。当我插入50毫秒的睡眠时也是一样的。但如果没有睡眠，它会混合这两个记录…

有人知道为什么会这样吗?每个线程不应该独立于自身吗?我也检查了收集和数据是正确的。

感谢

Oldfighter

c#多线程程序与WebRequest

Replace

Thread t = new Thread(() => Send(prov, c));
t.Start();


Thread t = new Thread(item => Send(item, c));
t.Start(prov);

在你的代码中lambda表达式实际上看到了迭代器变量的变化(它是每个线程的相同变量，而不是当你将lambda传递给线程构造函数时捕获的值)。

Classic foreach/capture;修复很简单——添加一个额外的变量:

foreach (Record tmp in list)
{
  Record prov = tmp;
  XMLResult.AppendText("Type: " + prov.Type + Environment.NewLine);
  Thread t = new Thread(() => Send(prov, c));                      

否则，" prove "在所有lambda之间共享。已经公开提到c# 5正在评估修复这个问题，但还没有确认。

您的问题是您正在访问Foreach循环中修改的闭包

:

        List<Thread> ThreadsPerOneRecord = new List<Thread>();
        bool ExecuteSingleThreaded = false;
        //The variable list is passed as parameter to the function  
        foreach (Record prov in list)
        {
            var tempProv = prov;
            XMLResult.AppendText("Type: " + tempProv.Type + Environment.NewLine);
            Thread t = new Thread(() => Send(tempProv, c));
            t.Start();
            //Here the sleep  
            Thread.Sleep(50);
            ThreadsPerOneRecord.Add(t);
            #region Code for test single threaded execution
            if (ExecuteSingleThreaded)
            {
                foreach (Thread t2 in ThreadsPerOneRecord)
                    t2.Join();
                ThreadsPerOneRecord.Clear();
            }
            #endregion
        }
        XMLResult.AppendText("Waiting for the threads to finish" + Environment.NewLine);
        //Waiting for the threads to finish 
        foreach (Thread t in ThreadsPerOneRecord)
            t.Join();
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