We are running a vary large DNN installation with over 300 child portals. We are running with DNN v4.9.4.

We have experienced a few problems recently with the amount of data that certain core DNN functions require from the database.

The worse offender at the moment is the GetAllTabs function. I found one fix in the DNN Gemini that has made a huge difference - : http://support.dotnetnuke.com/issue/ViewIssue.aspx

However we are all seeing this procedure being called from the GetPortalDictionary in the PortalController. What I am struggling to understand though are the repeated calls to the SP.

The function tries to get the PortalDictionary from the Cache. If it cannot find it, the PortalDictionary is recreated by calling the GetAllTabs SP and once complete, it stores it in cache. I recently amended the function to write to the event log every time it calls the GetAllTabs function.

What I am seeing is repeated calls to the GetAllTabs.  

My question is why would this happen?

Why is the code not finding the PortalDictionary in Cache (shown in blue below)?

Here is the code I am referring to:

        Public Shared Function GetPortalDictionary() As Dictionary(Of Integer, Integer)

             Dim key As String = DataCache.PortalDictionaryCacheKey

            ' retrieve from cache
            Dim portalDic As Dictionary(Of Integer, Integer) = TryCast(DataCache.GetCache(key), Dictionary(Of Integer, Integer))

            If portalDic Is Nothing Then
                ' create dictionary
                portalDic = New Dictionary(Of Integer, Integer)

                ' portal dictionary caching settings
                Dim timeOut As Int32 = DataCache.PortalDictionaryTimeOut * Convert.ToInt32(Common.Globals.PerformanceSetting)
 
                ' if caching is disabled, do not make this database call as it is too expensive on every request
                If timeOut > 0 Then
                    ' get all tabs
                    'My code to write to event Log                     Dim PS As Entities.Portals.PortalSettings                     PS = GetHostPortalSettings()                     Dim ctlrEventLog As New DotNetNuke.Services.Log.EventLog.EventLogController                     ctlrEventLog.AddLog("Calling GetAllTabs ", "", PS, -1, DotNetNuke.Services.Log.EventLog.EventLogController.EventLogType.ADMIN_ALERT)

                    Dim intField As Integer
                    Dim dr As IDataReader = DataProvider.Instance().GetAllTabs()
                    Try
                        While dr.Read
                            ' add to dictionary
                            portalDic(Convert.ToInt32(Null.SetNull(dr("TabID"), intField))) = Convert.ToInt32(Null.SetNull(dr("PortalID"), intField))
                        End While
                    Catch exc As Exception
                        LogException(exc)
                    Finally
                        ' close datareader
                        If Not dr Is Nothing Then
                            dr.Close()
                        End If
                    End Try
                    ' cache portal dictionary
                    DataCache.SetCache(key, portalDic, TimeSpan.FromMinutes(timeOut), True)
                End If
            End If

             Return portalDic
        End Function