Question : Strange recycling of ASP.NET worker process without hitting any pre-defined limits!

I've got a strange problem with an ASP.NET 2.0 application running on IIS6 on Win2k3.

The application was losing session-state randomly so my first thought was that we were in web-garden mode with multiple worker processes.  As it turns out we were, I reduced to 1 worker process but the problem remained, session state was being lost randomly.  After a little more analysis I noticed that when session-state was lost the Worker Process had recycled.  The event logged in the system log was as follows:

Event Type:      Information
Event Source:      W3SVC
Event Category:      None
Event ID:      1077
Date:            19/09/2007
Time:            12:38:03
User:            N/A
Computer:      SERVERNAME
Description:
A worker process with process id of '8512' serving application pool 'Appname' has requested a recycle because it reached its virtual memory limit.  

This app pool had it's virtual memory limit set to 512MB but the W3WP process never got higher than 26MB physical or VM!

Any ideas as to why IIS thought it had reached its limit when it fact it was miles away?

Thanks

Dave

Answer : Strange recycling of ASP.NET worker process without hitting any pre-defined limits!

Try to talk to developrs if possible. It seems that you are storing something big in session. What you see could be data related. Check if application was processing or was about to process some very big chunk of data just before recycling.
Another option which relatevly easy to try is to switch session server in Web.config to database. that should take care of data size issue, unless your database is often busy and request for session data will timeout.