Monitoring IIS real time - memory increases excessively till out of memory error

Question

We have a web-application that talks to a SQL Web database on another (database)server. Some queries make the memory on the web-server increase excessively till we receive an out of memory error. For instance, the RAM usage increases from 250MB tot 2300MB, and this all caused by the w3wp (yes, IIS) process.

Now my question is, what tools are there to monitor real time what is happening inside this IIS process. The stacktrace, maybe which objects are stored inside the RAM, etc

The server is running on Windows 2003 R2

Btw: I hear people thinking... google didn't help me a lot, the knowledge is here!

Thanks in advance!

Answer 1

I'm not a developer, so I can't tell you what you can instrument within your app. However, from the system:

1. Make sure this app has its own application pool, so that you can isolate what it's doing from any other processes.
2. As a stop-gap, maybe configure the pool to recycle after a max used memory of 2000 MB. This will be disruptive, but better than it using all the RAM and locking up.
3. Run Process Explorer from Sysinternal (Microsoft) while this is occurring. This will tell you a LOT of info about the process, including open file handles, GDI objects, etc.
4. Run Performance Monitor and look into the .NET CLR, Active Server Pages, and ASP.NET performance objects (as applicable to your application) to see if you can get some idea about what's doing the badness.

Answer 2

This isn't exactly real time, but you can use IIS Debug Diagnostics tool to generate a user dump when it detects a memory leak occurring.

You can then take that user dump into the DebugDiag to have it generate a report of memory usage in the dump.