Random Session Timeout in ASP.NET MVC3

Question

i have an application which gets random session timeouts. (IIS 7.5 on Windows 2008 R2, .NET 4.0)

i tried the following:

• checked the application log if the w3wp.exe process was crashed, but there is no entry.
• disabled in the application pool the rapid fail protection
• moved to the sql server state provider to be sure the loadbalancers sticky session is not the problem. (we use a kemp loadmaster).
• ensured that no other applications use the same application pool.
• checked that exceptions in a thread of a called assembly is correctly handled. (simulated using throw new exception) and the error handling was correct.
• ensured that the validationKey and decryptionKey is set in the webconfig on all 4 webservers to the same key.

i run now out of ideas how to spot this evil bug. any suggestions? i cannot reproduce the problem on my local machine in the debugger.

one point which is maybe important, the move from page 1 to page 2 where the session loss often happens, takes sometimes more than 120 seconds, because of a third party system which is connected via tcp socket.

Answer 1

HI Snoopy you linked to my question as they are similar,

As my appool was crashing I tried this solution. If your appool crash's this may help http://support.microsoft.com/kb/911816

the solution stop fix hack kept my app-pool up but didn't fix the problem,

<configuration>
<runtime>
    <legacyUnhandledExceptionPolicy enabled="true" />
</runtime>

If your app-pool is still intact you might try ELMAH as this helped me a lot http://code.google.com/p/elmah/

you can use this code to get ELMAH to handle unmanaged exceptions http://code.google.com/p/elmah/issues/detail?id=199

I am curious if it is MVC 3.0 problem with .net 4.0 as i have several very similar apps running using MVC 2.0 with no problems, Only started when I moved to MVC 3.0

Answer 2

Does it happen on a single server? Sure sounds like an issue with the web-farm.

Can you alter your app so you don't use the 3rd-party app for testing?

You have to eliminate pieces until the failure goes away, then add stuff back. Restore 3rd party app, turn other servers back on, etc.