We have a lot of tickets from clients complaining that our Web App is suddenly slow. The process has to be restarted nightly. It takes so long that some pages error out. Etc. In a nice twist, this is an IIS 6 Windows 2003 defect and can’t be reproduced on IIS 5.1 on Windows XP.
It seems we have isolated the problem to a bug introduced into IIS in Window 2003 SP2. The Session_OnEnd event in Global.asa does not get called. If you have any memory cleanup operations when someone logs out or the session times out they will not happen. The IIS process, w3wp or inetinfo, builds so much unreleased memory it gets really slow and starts failing.
My first few Google searches didn’t find anything. Then a co worker took some of my keywords and found a blog entry from an MS engineer which points to an MS article. The good news is that there is a patch to fix this problem. It took us ~24 hrs to get it after we diagnosed and found the problem.
I’m posting this blog entry to raise the profile of this problem on the search engines. It has been a very time consuming and frustrating issue here. I feel this absolutely should have been pushed out in a nightly hotfix from MS and it should have been shouted from the rooftops.