In Process Sessions in ASP.NET Application getting mixed up

[RajivBannur]

Hi,

We have an ASP.NET website that uses in process sessions to track some of
the user information stored across the web pages. 1 out of every 4 times we
see that the sessions getting mixed up resulting in malformed data and hence
the error. I’d like to share some data which was recorded on the production
server for a particular user for one session (please find below). Although we
use clustered environment, we do have a mechanism of sticky sessions tied up
to only one particular server which is done through network traffic
controllers. . To be more granular, we use serializable objects stored in a
session. Here is the snippet of code.

In BasePage.vb

Public ReadOnly Property OAUserSession() As UserSessionData
Get
If Session("UserSession") Is Nothing Then
_usd = New UserSessionData()
Session.Add("UserSession", _usd)
Else
_usd = CType(Session("UserSession"), UserSessionData)
End If
Return _usd
End Get
End Property


Page which stores the session

Me.OAUserSession.UserPurchaseContext.CurrentPackage = myPackage

OAUserSession, UserPurchaseContext and CurrentPackage are serializable
objects.

Page which retrieves the session

myPlaceOrder.CurrentPackage = OAUserSession.UserPurchaseContext.CurrentPackage


Every one of 4 times we have the session IDs getting mixed up. The
highlighted section below represents the values where the session values are
lost or mixed up.

Notes:

• The page use Response.Redirect to go to next page.
• Production boxes are installed with .NET 3.5 SP1 Fx
• 4 Production servers are being used with MS NLB. It's set to single
affinity, so a user coming from a specific IP will be sent to a specific
server for the duration of the session. So that the user maintains the same
connection with the server

Datetime Page Sequence Info
5/1/09 5:30 PM Before PriceId - 480, CustID - 36792, SessionID -
425nog45msby5xacp3ratm55
5/1/09 5:30 PM After CustID - 36792 , SessionID 425nog45msby5xacp3ratm55
5/1/09 5:31 PM Before PriceId - 480, CustID - 36792, SessionID -
g5nc0h55s3n4c0niypuvvs45
5/1/09 5:31 PM After Package - Empty Object , CustID - 36792 , SessionID
g5nc0h55s3n4c0niypuvvs45
5/1/09 5:35 PM After CustID - 36792 , SessionID buo2tyv2zq2nnzejuzyz3iig
5/1/09 5:35 PM Before PriceId - 480, CustID - 36792, SessionID -
buo2tyv2zq2nnzejuzyz3iig
5/1/09 5:38 PM Before PriceId - 480, CustID - 36792, SessionID -
buo2tyv2zq2nnzejuzyz3iig
5/1/09 5:38 PM After CustID - 36792 , SessionID buo2tyv2zq2nnzejuzyz3iig
5/1/09 5:39 PM Before PriceId - 480, CustID - 36792, SessionID -
bpplt345blweu345zakclcev
5/1/09 5:39 PM After Package - Empty Object , CustID - 36792 , SessionID
bpplt345blweu345zakclcev


Let us know if you need more information on this.

Thanks,
-Rajiv