We are running an ASP.NET 2.0 application under IIS8 on a x64 Windows Server 2012. This application was previously running on IIS6 on a windows server 2003 and we had a strange problem that we hoped that after the upgrade would be solved or at least be more"mild". Obviously it didn't.
Every now and then we had (and still have) a very strange excessive memory load on w3wp process serving the app pool of our application, which is dedicated to the app by the way. When this happens w3wp consumes all memory (22 out of 24 GB are assigned to
it) really fast (in less than a minute it goes from less than 1GB to 22GB) the pool recycles, application restarts, which means all sessions are ended (you call tell this from the phone calls also
) and what is the strangest of all is that when app restarts the same thing happens immediatelly for maybe 2 or
3 times continously most probably even before any user manages to login back to the application.
As the application handles big amounts of data, our first thought was someone asks for historical data that, when loaded from the database and before passed to the client, cause this. We tried reproducing it by requesting historical data for very very long periods but we only managed to add 0.5G to the process memory. Also viewing the IIS logs and comparing the dates and times this was occuring (when application restarts due to OOM event log is updated) we could not find anything suspicious. But even if one could find a way to load the server with so much data, the fact that immediately after app pool recycling the memory starts climbing again is something that we are not able to explain in any way.
Any ideas would be greatly appreciated as we have been trying to solve this for the several months now, in vain.