Annoying warning message regarding DynamicSupervisor

Phoenix Forum Questions / Help
, ,
1

Hello everyone,

I’m working my way through the book Programming Ecto, and everything is going really well except for this 15+ line warning messages I get every time I run mix. My OCD self cannot stand it anymore.

Here’s the warning:

warning: :simple_one_for_one strategy is deprecated, please use DynamicSupervisor instead
  (elixir 1.12.0) lib/supervisor.ex:604: Supervisor.init/2
  (elixir 1.12.0) lib/supervisor.ex:556: Supervisor.start_link/2
  (stdlib 3.15) supervisor.erl:414: :supervisor.do_start_child_i/3
  (stdlib 3.15) supervisor.erl:400: :supervisor.do_start_child/2
  (stdlib 3.15) supervisor.erl:384: anonymous fn/3 in :supervisor.start_children/2
  (stdlib 3.15) supervisor.erl:1234: :supervisor.children_map/4

warning: :simple_one_for_one strategy is deprecated, please use DynamicSupervisor instead
  (elixir 1.12.0) lib/supervisor.ex:604: Supervisor.init/2
  (elixir 1.12.0) lib/supervisor.ex:556: Supervisor.start_link/2
  (stdlib 3.15) supervisor.erl:414: :supervisor.do_start_child_i/3
  (stdlib 3.15) supervisor.erl:400: :supervisor.do_start_child/2
  (stdlib 3.15) supervisor.erl:384: anonymous fn/3 in :supervisor.start_children/2
  (stdlib 3.15) supervisor.erl:1234: :supervisor.children_map/4

warning: Supervisor.start_child/2 with a list of args is deprecated, please use DynamicSupervisor instead
  (elixir 1.12.0) lib/supervisor.ex:826: Supervisor.start_child/2
  (db_connection 2.0.5) lib/db_connection/watcher.ex:21: DBConnection.Watcher.handle_call/3
  (stdlib 3.15) gen_server.erl:721: :gen_server.try_handle_call/4
  (stdlib 3.15) gen_server.erl:750: :gen_server.handle_msg/6
  (stdlib 3.15) proc_lib.erl:226: :proc_lib.init_p_do_apply/3

And here is the, what I believe to be, the code to be modified

defmodule MusicDB.Application do
  @moduledoc false

  use Application

  def start(_type, _args) do
    children = [
      MusicDB.Repo
    ]
    opts = [strategy: :one_for_one, name: Test.Supervisor]
    Supervisor.start_link(children, opts)
  end
end

I’ve tried solving this, but all the explanations I’ve found go over my head at my current level of understanding. Can you help me out here?

2

You might find your answer here => migrating from supervisor simple one for one.

I don’t think your issue is that file either (the one you pasted here).

1 Like
3

The code sample is quite old and You might want to update some packages… maybe simply remove mix.lock before refetching deps.

The error is not in your code, but in a dependency which uses simple_one_for_one strategy.

I guess it’s coming from poolboy…

3 Likes
4

Thanks Koko, that was it!

For other newbies reading this, I deleted mix.lock and then run mix deps.get, and the warning disappeared.

1 Like