.net - PowerShell の使用中にメモリ リークが発生する

Question

VB.net で Power Shell を使用して Office 365 インスタンスに接続しています。これは正常に動作しますが、これが実行されているサービスのメモリ使用量が増え続けています。次のコードを使用して、Power Shell を開始して閉じています。 close メソッドが正しく機能していないようです。

Private Function initRunSpace(ByVal user_name As String, ByVal password_user As String) As String
   Dim StringBuilder As New StringBuilder
   Dim liveIdconnectionUri As String = "https://ps.outlook.com/powershell"
   Dim password As New SecureString()
   Dim str_password As String = password_user
   Dim username As String = user_name
   Dim credential As New PSCredential(username, password)
   Dim iss As InitialSessionState = Nothing
   Dim psSession As New PSCommand()
   Dim setVar As New PSCommand()
   Dim importSession As New PSCommand()

   Try
       For Each x As Char In str_password
           password.AppendChar(x)
       Next

       iss = InitialSessionState.CreateDefault
       iss.ImportPSModule(New String() {"MSOnline"})

       runspace = RunspaceFactory.CreateRunspace(iss)
       runspace.Open()
          powershell = System.Management.Automation.PowerShell.Create()
       powershell.Runspace = runspace
       REM connect to exchange server in the cloud

       psSession.AddCommand("New-PSSession")
       psSession.AddParameter("ConfigurationName", "Microsoft.Exchange")
       psSession.AddParameter("ConnectionUri", New Uri(liveIdconnectionUri))
       psSession.AddParameter("Credential", credential)
       psSession.AddParameter("Authentication", "Basic")
       psSession.AddParameter("AllowRedirection")
       powershell.Commands = psSession
       Dim result = powershell.Invoke()
       Dim errors As Collection(Of ErrorRecord) = Nothing
       errors = powershell.Streams.Error.ReadAll()

       If errors.Count > 0 Then
           REM Save the order or action for later execution
           For Each obj As Object In errors
               If obj IsNot Nothing Then StringBuilder.AppendLine(obj.ToString)
           Next
           powershell.Stop()
           powershell.Dispose()
           runspace.Close()
           runspace.Dispose()

           Return "Import-PSSession:" & StringBuilder.ToString
            End If
           Catch ex As Exception
          Throw ex
          Finally
          StringBuilder = Nothing
          liveIdconnectionUri = Nothing  
          password = Nothing
          str_password = Nothing
          username = Nothing
          credential = Nothing
          iss = Nothing
          psSession = Nothing
          setVar = Nothing
          importSession = Nothing
          End Try
          Return ""
      End Function




   Public Sub CloseRunspace()

   Dim removesession As New PSCommand()
   Try

       If powershell IsNot Nothing Then
           removesession.Commands.AddScript("Remove-PSSession $sa;Remove-Variable $sa;Remove-Module -Name MSOnline;")
           powershell.Commands = removesession
           powershell.Runspace = runspace
           Dim results As Collection(Of PSObject) = powershell.Invoke()

       End If
   Catch ex As Exception
   Finally
       removesession = Nothing
       powershell.Stop()
       powershell.Dispose()

       runspace.Close()
       runspace.Dispose()
       GC.Collect()
       Thread.Sleep(100)
   End Try
  End Sub