Session and Application Variables dissappearing

[William LaMartin]

I have a problem, mentioned here before, of Session and Application
variables disappearing at one site but not at others or on my development
computer.

The problem is illustrated by an example at
http://www.lamartin.com/dotnet/sessiontestset.aspx, were I set Session,
Application and Cache variables on the first page and then on the second
page view them as the second page is refreshed every five seconds. Before
10 refreshes, the variables have disappeared. Strangely, at least to me,
the Session Id can still be retrieved. So, under what circumstances do you
retain the Session ID but lose the Session variables?

The pages are hosted on a Windows 2003 server in a shared environment, but
not on a web farm. I have no control over this server, but the web host has
tried to solve the problem. However, they have not produced a solution.

What could be causing this?

 

[Alvin Bruney]

Where are you storing and passing session_id? The first thing which comes to
mind is examining the request recycle parameter in IIS management. Check to
see if it is set too low. If session_id is in the cache, my idea is totally
wrong. Post your code for that test page. This has definitely got my
interest.

regards

 

[William LaMartin]

I am not storing the Session ID. It is retrieved on every page reload of
the SessionTestView.aspx page.

Here is the code that sets the session and application variables in the page
sessiontestset.aspx:

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button1.Click
Application("Text") = "ABCDEF"
Session("Text") = "12345"
Cache.Add("Text", "STUVWXYZ", Nothing, DateTime.Now.AddMinutes(10),
TimeSpan.Zero, Caching.CacheItemPriority.AboveNormal, Nothing)
Response.Redirect("SessionTestView.aspx")
End Sub

Here is the code that displays the information in the page
SessionTestView.aspx (this page reloads every five seconds):

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
'Put user code to initialize the page here
Me.lblTime.Text = Now.ToString
Me.lblApplication.Text = "Application Variable: " &
Application("Text")
Me.lblSession.Text = "Session Variable: " & Session("Text")
Me.lblCache.Text = "Cached Variable: " & Cache.Item("Text")
Me.lblID.Text = "Session ID: " & Session.SessionID.ToString
End Sub

 

[Alvin Bruney]

ok check your settings in IIS. If this is IIS6 you want to check the
application pool properties recycle events and application shut down events
to see what they are set to. If this is ok, you will need to check your
config files for idletime directives in the process model node to see what
they are set to. If this is ok move on to the machine config file and check
the httpruntime nodes to see the recycling directives

regards

 

[William LaMartin]

I don't have access to this particular web server, so I have to request the
hosting company check. Thus I need to be specific.

It is IIS6. Is "application pool properties recycle events" the exact name
of the setting and what sort of value should it have? The same for
application shut down events.

I would love to figure this out, since I only have such problems on this
server. However, I have a number of sites hosted with his company and would
like to put more asp.net stuff on them if I can figure out Session variable
problem.

Here is the response from the hosting company when I first mentioned the
problem to them. Is it possible that some other user accessing a different
page is causing this problem:

your website has been moved into its own application pool, sharing it with
no one else. The logs indicate that the pool is failing when trying to run
some of your scripts. Operations suggest that there may be one small piece
of code somewhere in some of your pages which may be causing this, as your
website has been isolated on its own, and the pool that you were in
previously has not failed anymore.

 

[Alvin Bruney]

I think they are right.

problem to them. Is it possible that some other user accessing a different
page is causing this problem:

no, each user has his own stuff as long as the ...wait let me look at
something here...

Me.lblApplication.Text = "Application Variable: " &
this two lines will cause problems because these items are exposed to every
user hitting the website. You want to put them in session variables so they
are specific to a user. so that's one thing.

It likely is your code because of what they said. A wild guess? You have an
exception killing your cache objects. You will need to do some old fashion
debugging to figure this out. The problem most likely lies in your code.
Here is one place to begin. Remove all your catch blocks in your entire
application. In your application_error event, put script to display
Context.Error msg. Also, write a message to a static variable in your
session_end event in your global asax file. You need to see when the session
is ending. It may be ending prematurely. Put a button on the form to read
this static variable. Then test the page like you normally would. Any
exception will be displayed to the screen and you can go from there. I
figure you will have to debug on the server since the problem doesn't occur
on your machine.
It aint no picnic though, but have fun on the way.

regards

 

[William LaMartin]

I don't think it is my code, since at this other test site,
http://216.182.10.243/container/SessionTestSet.aspx, the variables don't
disappear. So it is something specific to the lamartin.com site
(http://www.lamartin.com/dotnet/sessiontestset.aspx). At lamartin.com, they
say they have put me in my own application pool, so it must be some other
setting.

I put the Application variable and the cached variable there only to see if
they would also disappear, and they do--at the same time the Session
variable does.

 

[Alvin Bruney]

Ok, well have them make these setting adjustments:
From the application pool property pages in IIS, uncheck all settings under
the Recycle tab (4)
From the Performance tab, uncheck the first two (Idle timeout and request
queue limit)
From the Health tab, uncheck Enable rapid-fail protection.

Let them know it is for debugging purposes because they might not be willing
as these settings compromise the stability of the server. In addition, have
them examine the idletimeout property in the machine config file to see what
it is set to. The default is Infinite otherwise it is a time period
00:00:00.

regards

 

[William LaMartin]

Thanks for all your input on this.

Before contacting the hosting company at the site exhibiting the problem
with disappearing session variables with your suggestions, I contacted the
fellow who is allowing me to test my applications at the site where the
session variables do not disappear. Regarding your Application Pool
settings, he said the settings in question on his server are:

Recycle Tab: recycle worker processes every 1740 minutes.
Performance Tab: shut down work processes after being idle for 20 minutes &
limit the kernel request queue to 4000 requests.
Health Tab: enable pinging every 30 seconds & enable rapid-fail protection.

Given that the above settings work, does that point to other settings as
possible problems?

 

[Alvin Bruney]

If these settings are the same on the faulty server/application, something
else is likely the issue.
At this point, I'm fresh out of ideas. I'd suggest you contact microsoft
about this so they can possibly take a memory dump and investigate further.
https://webresponse.one.microsoft.com/oas/public/assistedintro.aspx
you have 3 free requests you can make to microsoft if you originally
purchased the product which is the cause of the problem.

regards