VB.NET - Memory leak using while true loop, threads and wmi

Question

this code starts using 40 MB RAM and after 2 hours goes to 120 MB RAM. I tried to change some lines, but the used memory still goes up and up. What am I doing wrong? Is the while loop? Is the theads? Is the ContextDB.SaveChanges()?

UPDATE 1: Apparently the problem was resolved using "IsBackground = True" on the threads and disposing each "m" object. The used RAM is stable in 48 MB. Thanks guys.

Dim Work As New Thread(AddressOf MonitorServer)
Work.IsBackground = True 'Added this line
Work.Start(Server.ServerID)

Using searcher As New ManagementObjectSearcher(Scope, New ObjectQuery("SELECT * FROM Win32_OperatingSystem"))
    Using queryCollection = searcher.Get()
        For Each m In queryCollection
            Server.Host = m("csname")
            Server.OS = m("Caption")
            m.Dispose() 'Added this line
            m = Nothing 'Added this line
        Next
    End Using
End Using

.

UPDATE 2: The problem continues, after 24h, the code was using 350 MB !!!!

.

ORIGINAL CODE:

Full code: http://200.98.144.175/monitor.txt

Private Shared ServerList As New List(Of Server)

Private Shared Sub StartMonitor()

Using ContextDB As New EnvironmentMonitorEntities

    While True

        Dim Servers = (From A In ContextDB.Server).ToList

        For Each Server In Servers

            If Not ServerList.ToList.Contains(Server) Then

                ServerList.Add(Server)

                Dim Work As New Thread(AddressOf MonitorServer)
                Work.Start(Server) 'Start a thread for each server

            End If

        Next

        GC.Collect() 'Force CG
        Thread.Sleep(CInt(TimeSpan.FromSeconds(10).TotalMilliseconds)) 'Check new servers each 10 seconds

    End While

End Using

End Sub

Private Shared Sub MonitorServer(p As Object)

Dim Server = CType(p, Server)

Using ContextDB As New EnvironmentMonitorEntities

    While True

        Dim ServerID = Server.ServerID
        Dim ServerStatus = (From A In ContextDB.ServerStatus Where A.ServerID = ServerID).First
        Dim Scope As New ManagementScope("\\" + Server.IP + "\root\CIMV2")

        ServerStatus.LastUpdate = Now
        ContextDB.SaveChanges()

        Scope.Connect() 'Connect on server

        Alerts.SetServerStatus(ServerStatus, AlertType.Online)
        ContextDB.SaveChanges()

        Using searcher As New ManagementObjectSearcher(Scope, New ObjectQuery("SELECT * FROM Win32_OperatingSystem"))
            Using queryCollection = searcher.Get()
                For Each m In queryCollection
                    Server.Host = m("csname")
                    Server.OS = m("Caption")
                Next
            End Using
        End Using

        ContextDB.SaveChanges()

        Using searcher As New ManagementObjectSearcher(Scope, New ObjectQuery("SELECT * FROM Win32_Processor"))
            Using queryCollection = searcher.Get()
                For Each m In queryCollection
                    Server.Processor = m("Name")
                    Server.Architecture = m("Architecture")
                Next
            End Using
        End Using

        ContextDB.SaveChanges()

        Using searcher As New ManagementObjectSearcher(Scope, New ObjectQuery("SELECT * FROM Win32_OperatingSystem"))
            Using queryCollection = searcher.Get()
                For Each m In queryCollection
                    ServerStatus.RAMUsage = m("FreePhysicalMemory")
                    ContextDB.SaveChanges()
                Next
            End Using
        End Using

        GC.Collect()
        Thread.Sleep(CInt(TimeSpan.FromSeconds(3).TotalMilliseconds)) 'Monitor server each 3 seconds

    End While

End Using 'ContextDB

End Sub

Answer 1

Wow, as soon as you wrote the line GC.Collect() that should have been a cue that this is probably not the best way to solve this problem. Have you looked into Server Health Using PowerShell? I think this is much better suited to what you are doing, but only you can be the judge. Good luck.