defmodule MyServer do
  use GenServer
  def init(_args) do
    :gproc.reg({:p, :l, :my_little_server})
    {:ok, []}
  end

  def handle_info(msg, state) do
    IO.inspect "Got #{inspect msg} in process #{inspect self()}"
    {:noreply, state}
  end
end
#
# iex> {:ok, pid1} = GenServer.start_link(MyServer, [], [])
# iex> {:ok, pid2} = GenServer.start_link(MyServer, [], [])
# iex> :gproc.send({:p, :l, :my_little_server}, :hello_world)
# "Got :hello_world in process #PID<0.6726.0>"
# "Got :hello_world in process #PID<0.6728.0>"
# :hello_world