VB.net httpwebrequest For循环挂起每10个左右的迭代

Question

我想循环访问一个数组并在每次迭代中执行httpwebrequest。 该代码似乎工作，但它会暂停一段时间（例如比设置的超时时间更长，尝试将其设置为100来检查并且它仍然暂停），然后继续进行工作。

这里是我到目前为止有：

For i As Integer = 0 To numberOfProxies - 1 

      Try 
       'create request to a proxyJudge php page using proxy 
       Dim request As HttpWebRequest = HttpWebRequest.Create("http://www.pr0.net/deny/azenv.php") 
       request.Proxy = New Net.WebProxy(proxies(i)) 'select the current proxie from the proxies array 
       request.Timeout = 10000 'set timeout 

       Dim response As HttpWebResponse = request.GetResponse() 

       Dim sr As StreamReader = New StreamReader(response.GetResponseStream()) 
       Dim pageSourceCode As String = sr.ReadToEnd() 
       'check the downloaded source for certain phrases, each identifies a type of proxy 
       'HTTP_X_FORWARDED_FOR identifies a transparent proxy 
       If pageSourceCode.Contains("HTTP_X_FORWARDED_FOR") Then 
        'delegate method for cross thread safe 
        UpdateListbox(ListBox3, proxies(i)) 
       ElseIf pageSourceCode.Contains("HTTP_VIA") Then 
        UpdateListbox(ListBox2, proxies(i)) 
       Else 
        UpdateListbox(ListBox1, proxies(i)) 
       End If 

      Catch ex As Exception 
       'MessageBox.Show(ex.ToString) used in testing 
       UpdateListbox(ListBox4, proxies(i)) 
      End Try 
      completedProxyCheck += 1 
      lblTotalProxiesChecked.CustomInvoke(Sub(l) l.Text = completedProxyCheck) 

     Next 

我已经找遍了这个网站，并通过谷歌，以及这类问题的大多数答复说，响应必须关闭。我已经尝试了使用块，如：

Using response As HttpWebResponse = request.GetResponse() 
Using sr As StreamReader = New StreamReader(response.GetResponseStream()) 
    Dim pageSourceCode As String = sr.ReadToEnd() 
        'check the downloaded source for certain phrases, each identifies a type of proxy 
        'HTTP_X_FORWARDED_FOR identifies a transparent proxy 
        If pageSourceCode.Contains("HTTP_X_FORWARDED_FOR") Then 
         'delegate method for cross thread safe 
         UpdateListbox(ListBox3, proxies(i)) 
        ElseIf pageSourceCode.Contains("HTTP_VIA") Then 
         UpdateListbox(ListBox2, proxies(i)) 
        Else 
         UpdateListbox(ListBox1, proxies(i)) 
        End If 
End Using 
End Using 

而且它没有什么区别（虽然我可能已经实现了这是错误的）你可以告诉IM到VB很新或任何OOP所以它可能是一个简单的问题，但我不能解决它。

任何意见或只是提示如何诊断这些类型的问题将非常感激。编辑： 现在即时通讯彻底困惑。 try catch语句是否自动关闭响应，还是我需要在finally中放置一些东西？如果是这样，什么？我不能使用response.close（），因为它在try块中声明。

也许我只是使用非常糟糕的结构化代码，并有更好的方法来做到这一点？或其他什么导致暂停/挂起？

Answer 1

因为在评论中编写代码非常困难，我将继续作为回答。

For i As Integer = 0 To numberOfProxies - 1 
Dim response As HttpWebResponse 
    Try 
     'create request to a proxyJudge php page using proxy 
     Dim request As HttpWebRequest = HttpWebRequest.Create("http://www.pr0.net/deny/azenv.php") 
     request.Proxy = New Net.WebProxy(proxies(i)) 'select the current proxie from the proxies array 
     request.Timeout = 10000 'set timeout 

     response = request.GetResponse() 

     Dim sr As StreamReader = New StreamReader(response.GetResponseStream()) 
     Dim pageSourceCode As String = sr.ReadToEnd() 
     'check the downloaded source for certain phrases, each identifies a type of proxy 
     'HTTP_X_FORWARDED_FOR identifies a transparent proxy 
     If pageSourceCode.Contains("HTTP_X_FORWARDED_FOR") Then 
      'delegate method for cross thread safe 
       UpdateListbox(ListBox3, proxies(i)) 
     ElseIf pageSourceCode.Contains("HTTP_VIA") Then 
       UpdateListbox(ListBox2, proxies(i)) 
     Else 
       UpdateListbox(ListBox1, proxies(i)) 
     End If 

    Catch ex As Exception 
     'MessageBox.Show(ex.ToString) used in testing 
     UpdateListbox(ListBox4, proxies(i)) 
    Finally 
     response.Close() 
    End Try 
    completedProxyCheck += 1 
    lblTotalProxiesChecked.CustomInvoke(Sub(l) l.Text = completedProxyCheck) 

Next 

Answer 2

呀，你需要关闭的响应，你用它做之后，如.NET强制执行的并发请求

的最大数量

所以只需添加

response.close() 

在你的代码块结束