VB.net httpwebrequest For循環掛起每10個左右的迭代

Question

我想循環訪問一個數組並在每次迭代中執行httpwebrequest。 該代碼似乎工作，但它會暫停一段時間（例如比設置的超時時間更長，嘗試將其設置爲100來檢查並且它仍然暫停），然後繼續進行工作。

這裏是我到目前爲止有：

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 

我已經找遍了這個網站，並通過谷歌，以及這類問題的大多數答覆說，響應必須關閉。我已經嘗試了使用塊，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 

而且它沒有什麼區別（雖然我可能已經實現了這是錯誤的）你可以告訴IM到VB很新或任何OOP所以它可能是一個簡單的問題，但我不能解決它。

任何意見或只是提示如何診斷這些類型的問題將非常感激。編輯： 現在即時通訊徹底困惑。 try catch語句是否自動關閉響應，還是我需要在finally中放置一些東西？如果是這樣，什麼？我不能使用response.close（），因爲它在try塊中聲明。

也許我只是使用非常糟糕的結構化代碼，並有更好的方法來做到這一點？或其他什麼導致暫停/掛起？

Answer 1

因爲在評論中編寫代碼非常困難，我將繼續作爲回答。

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，你需要關閉的響應，你用它做之後，如.NET強制執行的併發請求

的最大數量

所以只需添加

response.close() 

在你的代碼塊結束