Getting IIS Worker Process Crash dumps

Question

I'm doing something bad in my ASP.NET app. It could be the any number of CTP libraries I'm using or I'm just not disposing something properly. But when I redeploy my ASP.NET to my Vista IIS7 install or my server's IIS6 install I crash an IIS worker process.

I've narrowed the problem down to my HTTP crawler, which is a multithreaded beast that crawls sites for useful information when asked to. After I start a crawler and redeploy the app over the top, rather than gracefully unloading the appDomain and reloading, an IIS worker process will crash (popping up a crash message) and continue reloading the app domain.

When this crash happens, where can I find the crash dump for analysis?

Osmic

These demos should be able to help you. – Precise

Answer 1

Download Debugging tools for Windows: http://www.microsoft.com/whdc/DevTools/Debugging/default.mspx

Debugging Tools for Windows has has a script (ADPLUS) that allows you to create dumps when a process CRASHES: http://support.microsoft.com/kb/286350

The command should be something like (if you are using IIS6):

cscript adplus.vbs -crash -pn w3wp.exe

This command will attach the debugger to the worker process. When the crash occurs it will generate a dump (a *.DMP file).

You can open it in WinDBG (also included in the Debugging Tools for Windows). File > Open Crash dump...

By default, WinDBG will show you (next to the command line) the thread were the process crashed.

The first thing you need to do in WinDBG is to load the .NET Framework extensions:

.loadby sos mscorwks

then, you will display the managed callstack:

!clrstack

if the thread was not running managed code, then you'll need to check the native stack:

kpn 200

This should give you some ideas. To continue troubleshooting I recommend you read the following article:

http://msdn.microsoft.com/en-us/library/ee817663.aspx

Teach

FYI adplus.vbs has been replaced by adplus.exe in the most recent version of Debugging tools for Windows. – Tomi

Does ADPlus.exe attach to the w3p.exe process? I'm assuming so .. but what happens if that process recycles ? – Favien

Can I use adplus.vbs for IIS 7 - 7.5 ? – Lozier

Answer 2

A quick search found IISState - it relies on the Windows debugging tools and needs to be running when a crash occurs, but given the circumstances you've described, this shouldn't be a problem,

Citadel