What is the supervisor process in Elixir?
Overview
A supervisor is a process that supervises other child processes and restarts them whenever they crash. To do so, supervisors monitor the complete life-cycle of any supervised processes, including both startup and shutdown.
Myapp.Supervisor.start_link
defmodule Chat.MixProject do
use Mix.Project
def project do
[
app: :chat,
version: "0.1.0",
elixir: "~> 1.13",
start_permanent: Mix.env() == :prod,
deps: deps()
]
end
# Run "mix help compile.app" to learn about applications.
def application do
[
extra_applications: [:logger]
]
end
# Run "mix help deps" to learn about dependencies.
defp deps do
[
# {:dep_from_hexpm, "~> 0.3.0"},
# {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"}
]
end
end
Child specification
In lines 7-8 of the supervisor.ex file, we pass a tuple with the module name to specify the child processes. Here, we use a simpler child specification that requires less reconfiguration. Using these child specifications, we can specify how a child behaves. The child specification is usually a map and contains up to 6 elements. id, start, restart, shutdown, type and modules are all 6 of them.
Supervision tree
A supervision tree models a behavior whose only job is to monitor one or many processes. These processes may be both child processes or child supervisors.
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