Get sharepoint w3wp.exe process memory dump using the winDBG

Question

Hi all

I try to use the winDBG (adplus) to dump the w3wp process.

When I run this command adplus.vbs -hang -quiet -p ****, I found it create a folder with a big size file, and the size was growing. Then suddenly, the big size file disappeared and the process re-start again. Does anyone know about it?

Best Regards,

Answer 1

I can only imagine the memory usage of the w3wp process got to much which triggered an app pool recycle, which means restarting w3wp.

Answer 2

Yongwei,

Colin is right; in effect, you're racing against IIS as it is recylcing the application pool. As you're snapping your process snapshot, you're either hitting a memory-threshold for recycling, or health checks are perceiving the process to be hung and instituting a recycle (possibly due to ADPlus locking the process)

Here's how I would modify your application pool characteristics prior to attempting your next capture. You only need these changes in effect for as long as it takes to capture your dump:

• Turn off memory-based recycling limits (physical and virtual)
• Turn off the idle timeout limit (if it's on)
• Disable both Pinging and Rapid Fail Protection

In effect: you need to turn off all of the features that try to keep your app pools running well. Capturing a memory snapshot takes time (as you know).

I would also recommend checking out ProcDump (http://technet.microsoft.com/en-us/sysinternals/dd996900.aspx) from the SysInternals guys. It was just released last month, and it makes process memory captures a bit easier. An article on using it to capture the W3WP is here: http://blogs.msdn.com/webtopics/archive/2009/08/08/using-procdump-exe-to-monitor-w3wp-exe-for-cpu-spikes.aspx

I hope this helps!