How to get the details of W3WP processes for each app pool running on your server
Run this command from System32 folder
Cscript iisapp.vbs
Output will be in the format:
W3WP.exe PID: 1468 AppPoolId: AppPoolForSite1.com
W3WP.exe PID: 3056 AppPoolId: AppPooForSite2.com
W3WP.exe PID: 1316 AppPoolId: AppPooForSite3.com