CODEWITHSUNDEEP
heroku
philosopher
philosopher

Reputation: 1151

Will Heroku dyno automatic restarts kill running processing on my application?

I have an application that is hosted on Heroku. The application has a process that is run on the server, that the user has the ability to start and stop. Once the user clicks 'Start', the process is supposed to stay running until the user presses 'Stop'. The functionality of the app should allow that the process can be run for extended periods of times (6 months or so) continuously.

I have deployed my app on a Heroku free dyno. While reading the Heroku documentation, I came across this page that states that Heroku Dynos are restarted automatically every 24 hours. Here is the relevant passage:

Dynos are also restarted (cycled) at least once per day to help maintain the health of applications running on Heroku. Any changes to the local filesystem will be deleted. The cycling happens once every 24 hours (plus up to 216 random minutes, to prevent every dyno for an application from restarting at the same time). Manual restarts (heroku ps:restart) and releases (deploys or changing config vars) will reset this 24 hour period. Cycling happens for all dynos, including one-off dynos, so dynos will run for a maximum of 24 hours + 216 minutes. If you have multiple dynos, they should cycle at different times based on the random 0 to 216 minutes difference. If you continually make changes to your application without a 24 hour gap, you won’t see cycling at all.

Does this mean that the user process that he/she has started will automatically be stopped when the dyno restarts? If yes, does it automatically resume the user process where it left off?

If not, I will have to find a different hosting solution since the process may need to be run 24x7x365.

Upvotes: 1

Views: 2142

Answers (1)

Denis Cornehl
Denis Cornehl

Reputation: 4182

Does this mean that the user process that he/she has started will automatically be stopped when the dyno restarts?

Yes it does. As it will when you change config variables, or deploy updates, or add / remove addons.

If yes, does it automatically resume the user process where it left off?

No it doesn't. Any safe-and-resume behaviour you have to implement in your application. When stopping processes, Heroku will send them a SIGTERM signal and give them 30 seconds to safe their work.

If not, I will have to find a different hosting solution since the process may need to be run 24x7x365.

I doubt that there is any hosting solution that will give you what you want. In a cloud environment restarts are a thing that happens all the time, at least for you updating your application, bugfixes, security fixes. Every hosting provider or platform that provides you with 24x7x365 uptime will also restart and replace your dynos all the time.

Upvotes: 3

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