AppPool and worker process

A simple question:

Is the AppPool same as the worker process w3wp?

If this is the case when the w3wp.exe shuts down after "idle timeout" why does the AppPool show as still running on the IIS Manager?

Also, when the w3wp.exe shuts down after "idle timeout",开发者_StackOverflow社区 does it not restart automatically? or does it restart only when traffic comes into the website again?

Any help is appreciated.

An app pool can host (as the name implies) multiple processes. In that case there will be several w3wp.exe processes associated with a single app pool. This can occur when app pool settings cause an app pool process to be recycled. While the old w3wp.exe is drained down of existing connections a new one is spun up to handle new traffic.

W3WP processes, AFAIK, are only created when there is incoming traffic. A request is necessary to start the process - it is not like an NT service that starts on its own.