erlang,elixir,otp , Getting a sibling process in Elixir

Getting a sibling process in Elixir


Tag: erlang,elixir,otp

I have an Elixir/Erlang process tree:

parent (Supervisor)
├── child1 (GenServer)
└── child2 (GenServer)

child1 (a DB client) has information that child2 needs to use. What's a good way to pass a reference from the Supervisor process to child2 so that child2 will always have a valid reference to child1? Do I just need to restructure my app so that child2 is supervised by child1?


The simplest way would probably be for child1 and child2 to be registered under local aliases. You can do that while starting your GenServer by passing the name option:

defmodule Child1 do
  use GenServer

  def start_link do
    GenServer.start_link(__MODULE__, [], name: __MODULE__)

In this case a process backed by the Child1 module will be registered locally under an alias Child1. Then if you want to send it messages you can use that alias instead of a PID.

defmodule Child1 do
  # ...

  def get_data do, :get_data)

  def handle_call(:get_data, _from, state) do
    {:reply, extract_data_from_state(state), state}

If you want a more complex solution where for example many different processes of the same type may be registered, take a look at the gproc library


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