HttpListener 性能优化

Question

我使用 HttpListener 作为一个简单的 http 服务器。我一直在通过让 HttpListener 向每个请求返回字符串“OK”来对请求/秒性能进行基准测试——这已经达到每秒 16,000 个请求的限制。基于以下代码，我可以做些什么来进一步优化性能？还是我们达到了 Windows Http.sys 的极限？

图片上传不工作，这里是 Visual Studio 性能跟踪的链接：

VS Performance Trace

Public Class HTTPServer

    Shared Listener As HttpListener = New HttpListener

    Public Shared Sub Start()

        ServicePointManager.DefaultConnectionLimit = 500
        ServicePointManager.Expect100Continue = False
        ServicePointManager.MaxServicePoints = 500

        Listener.Prefixes.Add("http://localhost/")
        Listener.Start()

        For i As Integer = 1 To (System.Environment.ProcessorCount * 2)

            Dim NewThread As New System.Threading.Thread(AddressOf ListenerThread)
            NewThread.Priority = ThreadPriority.Normal
            NewThread.IsBackground = True
            NewThread.Start()

        Next

    End Sub



    Private Shared Sub ListenerThread()

        Dim SyncResult As IAsyncResult

        While True

            SyncResult = Listener.BeginGetContext(New AsyncCallback(AddressOf ListenerCallback), Listener)
            SyncResult.AsyncWaitHandle.WaitOne()

        End While

    End Sub



    Private Shared Sub ListenerCallback(ByVal StateObject As IAsyncResult)

        Dim Listener As HttpListener = DirectCast(StateObject.AsyncState, HttpListener)

        Dim Context As HttpListenerContext = Listener.EndGetContext(StateObject)
        Dim Request As HttpListenerRequest = Context.Request

        Dim Response As HttpListenerResponse = Context.Response

        Dim ResponseString As String = "OK"

        Dim Buffer As Byte() = System.Text.Encoding.UTF8.GetBytes(ResponseString)
        Response.ContentLength64 = Buffer.Length
        Dim OutputStream As System.IO.Stream = Response.OutputStream
        OutputStream.Write(Buffer, 0, Buffer.Length)

        OutputStream.Close()
        OutputStream.Dispose()

    End Sub

End Class

Answer 1

嗯一个你可以做的就是只调用一次Encoding.UTF8.GetBytes("OK")，而不是每次请求。我怀疑它会产生很大的不同，但如果您对每个请求都执行完全相同的操作，那么您最好以您需要的形式获得响应。

我也会使用Using 语句，而不是显式调用 Close 和 Dispose。这不是性能问题 - 只是在出现异常时避免未关闭流出现问题的一般良好做法。

实际上，您需要达到超过 16K QPS 吗？你确定你是受 CPU 限制还是 IO 限制？一旦您的程序需要对每个请求实际执行一些实际工作，我想这将使您在这里所做的任何微优化都相形见绌。