HttpListener性能优化

Question

我使用HttpListener作为简单的http服务器。我一直在对请求/秒性能进行基准测试，让HttpListener为每个请求返回字符串"OK“-这达到了每秒16,000个请求的限制。基于下面的代码，我能做些什么来进一步优化性能呢？还是说，我们正在触及Windows Http.sys的极限？

图像上传不起作用，这里有一个指向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

你可以做的一件事就是只调用Encoding.UTF8.GetBytes("OK")一次，而不是每次请求都调用。我怀疑这会有多大的不同，但如果您对每个请求都执行完全相同的操作，那么您还不如以所需的形式获得响应。

我也会使用Using语句，而不是显式地调用Close和Dispose。这不是性能上的问题--只是当出现异常时避免未关闭的流出现问题的一般良好实践。

实事求是地说，你需要达到16K以上的QPS吗？你有没有弄清楚你是受CPU限制还是受IO限制？一旦你的程序需要对每个请求做一些实际的工作，我想这将使你在这里所做的任何微优化都相形见绌。