Windows Service HTTPListener Memory Issue
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by crawshaws
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Published on 2010-04-30T09:48:15Z
Indexed on
2010/04/30
10:17 UTC
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Hi all,
Im a complete novice to the "best practices" etc of writing in any code. I tend to just write it an if it works, why fix it.
Well, this way of working is landing me in some hot water. I am writing a simple windows service to server a single webpage. (This service will be incorperated in to another project which monitors the services and some folders on a group of servers.)
My problem is that whenever a request is recieved, the memory usage jumps up by a few K per request and keeps qoing up on every request.
Now ive found that by putting GC.Collect in the mix it stops at a certain number but im sure its not meant to be used this way. I was wondering if i am missing something or not doing something i should to free up memory.
Here is the code:
Public Class SimpleWebService : Inherits ServiceBase
'Set the values for the different event log types.
Public Const EVENT_ERROR As Integer = 1
Public Const EVENT_WARNING As Integer = 2
Public Const EVENT_INFORMATION As Integer = 4
Public listenerThread As Thread
Dim HTTPListner As HttpListener
Dim blnKeepAlive As Boolean = True
Shared Sub Main()
Dim ServicesToRun As ServiceBase()
ServicesToRun = New ServiceBase() {New SimpleWebService()}
ServiceBase.Run(ServicesToRun)
End Sub
Protected Overrides Sub OnStart(ByVal args As String())
If Not HttpListener.IsSupported Then
CreateEventLogEntry("Windows XP SP2, Server 2003, or higher is required to " & "use the HttpListener class.")
Me.Stop()
End If
Try
listenerThread = New Thread(AddressOf ListenForConnections)
listenerThread.Start()
Catch ex As Exception
CreateEventLogEntry(ex.Message)
End Try
End Sub
Protected Overrides Sub OnStop()
blnKeepAlive = False
End Sub
Private Sub CreateEventLogEntry(ByRef strEventContent As String)
Dim sSource As String
Dim sLog As String
sSource = "Service1"
sLog = "Application"
If Not EventLog.SourceExists(sSource) Then
EventLog.CreateEventSource(sSource, sLog)
End If
Dim ELog As New EventLog(sLog, ".", sSource)
ELog.WriteEntry(strEventContent)
End Sub
Public Sub ListenForConnections()
HTTPListner = New HttpListener
HTTPListner.Prefixes.Add("http://*:1986/")
HTTPListner.Start()
Do While blnKeepAlive
Dim ctx As HttpListenerContext = HTTPListner.GetContext()
Dim HandlerThread As Thread = New Thread(AddressOf ProcessRequest)
HandlerThread.Start(ctx)
HandlerThread = Nothing
Loop
HTTPListner.Stop()
End Sub
Private Sub ProcessRequest(ByVal ctx As HttpListenerContext)
Dim sb As StringBuilder = New StringBuilder
sb.Append("<html><body><h1>Test My Service</h1>")
sb.Append("</body></html>")
Dim buffer() As Byte = Encoding.UTF8.GetBytes(sb.ToString)
ctx.Response.ContentLength64 = buffer.Length
ctx.Response.OutputStream.Write(buffer, 0, buffer.Length)
ctx.Response.OutputStream.Close()
ctx.Response.Close()
sb = Nothing
buffer = Nothing
ctx = Nothing
'This line seems to keep the mem leak down
'System.GC.Collect()
End Sub
End Class
Please feel free to critisise and tear the code apart but please BE KIND. I have admitted I dont tend to follow the best practice when it comes to coding.
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