I know that the event handler for this event is called when the application pool is recycled by IIS, but when does that happen? What about if using the built-in Visual Studi
Like Nick said, "An application pool will recycle when... some of the recycle limits are hit on the application pool configuration." In IIS you can set the recycling conditions in the application pool settings. You can use fixed intervals (every X minutes or requests), a specific time of day, or memory-based maximums in MB (max virtual memory or max private memory), or a combination of any of these. You can also set an idle time-out in minutes after which a worker process is terminated.