What is a supervisor?

A supervisor is an OTP process whose only job is to start, monitor, and restart a set of child processes according to a restart strategy. It doesn't do business logic itself — it exists purely to keep its children alive.

init([]) ->
    {ok, {{one_for_one, 5, 10},
          [{worker1, {my_worker, start_link, []},
            permanent, 5000, worker, [my_worker]}]}}.

Common strategies include one_for_one (restart only the child that died), one_for_all (restart every sibling if one dies), and rest_for_one (restart the failed child and any children started after it). Chaining supervisors into a tree, with workers as leaves, is what gives Erlang systems their self-healing behavior after a crash.

Invest now in Acorns!!! 🚀
Join Acorns and get your $5 bonus!

Acorns is a micro-investing app that automatically invests your "spare change" from daily purchases into diversified, expert-built portfolios of ETFs. It is designed for beginners, allowing you to start investing with as little as $5. The service automates saving and investing. Disclosure: I may receive a referral bonus.

Invest now!!! Get Free equity stock (US, UK only)!

Use Robinhood app to invest in stocks. It is safe and secure. Use the Referral link to claim your free stock when you sign up!.

The Robinhood app makes it easy to trade stocks, crypto and more.

Webull! Receive free stock by signing up using the link: Webull signup.