Do we need to close the System.Net.WebRequest's ResponseStream?

I was wondering will I end up having any unclosed streams from this code:

   Public Function [Get](ByVal url As String) As String
        Using reader = New System.IO.StreamReader(System.Net.WebRequest.Create(url).GetResponse.GetResponseStream)
            Return reader.ReadToEnd
        End Using
    End Function

What about this:

  Public Function Get2(ByVal url As String) 开发者_StackOverflow中文版As String
        Using stream = System.Net.WebRequest.Create(url).GetResponse.GetResponseStream
            Using reader = New System.IO.StreamReader(stream)
                Return reader.ReadToEnd
            End Using
        End Using
    End Function

Basically, do we need to close the System.Net.WebRequest's ResponseStream ?

You either need to close the response stream or you need to close the response. Note that closing a StreamReader wrapping a Stream will close the stream anyway, so the first version should be okay. (Note that I'm deeming "dispose with a Using statement" to be semantically equal to "close in a finally block" - there's no benefit in explicitly calling Close instead of just disposing of the stream or response.)

I believe that closing the stream is good enough - that you don't need to close the response as well - and indeed that's what MSDN states, but personally I'd do so for clarity:

Public Function [Get](ByVal url As String) As String
    Using response = WebRequest.Create(url).GetResponse
        Using reader = New System.IO.StreamReader(response.GetResponseStream)
            Return reader.ReadToEnd
        End Using
    End Using
End Function

(There's a theoretical benefit here that it will close the response if GetResponse returns successfully but either GetResponseStream or the StreamReader constructor throws an exception. I don't expect that to have any practical implications.)

If you don't close anything, you could very easily run into timeouts in future requests to the same host - the "open" response will essentially hog the connection to that host, and by default there's a limit of two open connections per host. This is a very common cause of timeouts - there are lots of SO questions where folks are getting timeouts due to not closing anything.

It is not necessary to call the Close method on the WebResponse, but doing so is not harmful

http://msdn.microsoft.com/en-us/library/debx8sh9.aspx