IIS 6 / COM + freezes

Question

I have a web application that sometimes just hangs over a heavy load. To get it back, I have to kill the "dllhost.exe" process. Does anyone know what to do?

This is a Classic ASP (VBScript) application with many COM + objects.

The server has the following configuration:

• Intel Core 2 Duo 2.2 GHz / 4 GB RAM
• Windows Server 2003 Web Edition SP2
• IIS 6.0

There are some errors in the event log related to COM objects. But why errors in COM objects can cause the entire server to fail?

COM objects - PowerBuilder objects deployed as COM objects.

Is IIS 7.0 (much) more stable than IIS 6.0?

Answer 1

Sounds like dodgy COM objects causing a problem. You load them into the "Application", if you do, they are thread safe; or are they used and discarded for each request?

Yes, recycling every few hours will help to “hide” the problem, but they should be debugged and corrected correctly ... you tried to divide / win to find out which COM object is the problem ... I can imagine it is difficult in a production environment, so you need to configure some heavy automated tests to reproduce the problem locally, then you can do something with it.

Answer 2

You have a memory leak :)

This blog post is my IIS troubleshooting bible:

http://blogs.msdn.com/david.wang/archive/2005/12/31/HOWTO_Basics_of_IIS6_Troubleshooting.aspx

If you cannot verify your code and find where the reference leaks are, an alternative is to restart the application by restarting IIS every 24 hours or so. You can simply configure the script command line as the server job for this.

Answer 3

There are probably some errors in your application and system categories in your event log. Try to find the origin of these errors or post them here, we will see what we can do :)

Edit: @ Daniel Silveira Chance of a memory leak. What COM + object are you using? I had some problems with Excel with application support.