Start child after it was terminated

Questions / Help
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1

Hello People, I have Supervisor that starts children dynamically with an ID {Wms.Queue.Worker.Dummy, 2} I want that child to be terminated and I am doing it with

  def handle_info(:timeout, state) do
    {:stop, :normal, state}
  end

I’m using the option restart: :transient so when it terminates the supervisor does not restart it, But I want to start_child manually later.
When I try to start it again it tells me

** (exit) exited in: GenServer.call(Wms.Queue.Worker.Dummy, {:terminate_child, {Wms.Queue.Worker.Dummy, 2}}, :infinity)
    ** (EXIT) no process: the process is not alive or there's no process currently associated with the given name, possibly because its application isn't started
    (elixir) lib/gen_server.ex:999: GenServer.call/3

And it is because the children are still registered in the supervisor with a undefined PID

Supervisor.which_children(Wms.Queue.Worker.Dummy.Pool)
[
  {{Wms.Queue.Worker.Dummy, 2}, :undefined, :worker, [Wms.Queue.Worker.Dummy]},
  {{Wms.Queue.Worker.Dummy, 1}, :undefined, :worker, [Wms.Queue.Worker.Dummy]}
]

Could someone explain to me why the terminated child is not deleted from there, and which is the best way?

2

Is it a DynamicSupervisor?

If not, you should convert it to such and then manually start the children initially. This should give you the freedom to then manually restart them whenever the time is right.

1 Like
3

Can you show how you start the process initially? Is the process linked to the dynamic supervisor?

4

It took me some time to convert it, but at the end it was the solution, Do you know If I Can put names to the children of the dynamic supervisor?

5

Check out the Supervisor top-level docs, they explain to you the possible ways to provide a child_spec for the started sub-tasks. Yes, you can have whatever ID/name you like for them.

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