App Sleeping on Heroku
June 20, 2013 by Mark Pundsack
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 an app on Heroku has only one web dyno and that dyno doesn't receive any traffic in 1 hour, the dyno goes to sleep.
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 have more than 1 web dyno running never go to sleep and worker dynos (or other process types) are never put to sleep.
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 1 hour of inactivity
- 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.