When and Why App Sleep on Heroku

When talking to Heroku users, a question that frequently comes up is “when do my apps go to sleep, and why?”. Though the behavior is documented in Dev Center, we’d like to provide more immediate visibility into the state of your apps at any given moment.

When Do Apps Sleep?

When an app on Heroku has an Eco web dyno, and that dyno receives no web traffic in a 30-minute period, it sleeps. In addition to the web dyno sleeping, if you have an Eco worker dyno, it also sleeps.
When someone accesses the app, the dyno manager will automatically wake up the web dyno to run the web process type. This causes a short delay for this first request, but subsequent requests will perform normally.

Apps that only use an Eco worker dyno don’t sleep, because they don’t respond to web requests.

Wakefulness in Dashboard

Starting today, we’ll be exposing the wakefulness of your apps on your Dashboard app list.

All your apps now have an icon to indicate their current state. Here are the possible states your app can be in:

• Awake and will never go to sleep
• Awake, but will go to sleep after 30 minutes of inactivity
• Asleep
• Not running because it has been scaled down or has no code

You can click on any of the icons to see more information, such as how long the app has been sleeping for, and a quick shortcut to wake it up again if it is asleep.