This does two negative things to your website. 1) It will timeout any user sessions regardless of what you specify the default timeout to be (again this assumes they're inactive for at least 20 minutes), and 2) it will unload the application completely so that when a user goes to your website, it has to go through all of the initial application load and startup events all over again (for my site this would usually take up to 15 seconds until the page responded).
So it seems the best option to solve this issue is to ping your website every 19 minutes. But how do you do that with a solution that happens automatically, doesn't depend on any person or local machine with internet, and is cost-effective?
I found a free site monitoring tool called StatusCake that I'm now happily using to ping my website in 15 minute intervals.
I also tried out StillAlive which is an official AppHarbor addon that is free with limited functionality. The main problem being it only allows you to make a call every 4 hours under the free plan.
Monitor.us is another free service that has tons of features that I looked into. What I found was that StatusCake was a lot simpler to setup and manage. Also, the lowest interval I remember seeing was 30 minutes but I could be wrong.
