High CPU consumption in my user micro service

Hello, I have a micro service that its job is manage my users, this micro service when is running and even without managing many user, or 0 user , it spends 20% cpu in developer mode, It is interesting to know, I have no error which makes me understand!! For this purpose I have no options to test my project.

How can I find this problem and fix this ?

erlang v: 20.3.1
elixir v: 1.6.4
phoenix v: 1.3.3
node v: 9.3.0
other container Redis v: 4.0.11
other container Postgresql v: 10.5

my lib in elixir project:

  defp deps do
    [
      {:postgrex, ">= 0.0.0"},
      {:ecto, "~> 2.1"},
      {:guardian, "~> 1.0"},
      {:jose, "~> 1.8"},
      {:httpoison, "~> 1.0"},
      {:plug, "~> 1.4"},
      {:comeonin, "~> 4.0"},
      {:bcrypt_elixir, "~> 1.0"},
      {:redix, "~> 0.7.0"},
      {:phoenix, "~> 1.3.0"},
      {:exq, "~> 0.10.1"},
      {:bamboo, "~> 1.1"},
      {:timex, "~> 3.4"},
      {:bamboo_smtp, "~> 1.6.0"}
    ]
  end

in phoenix project :

[
      {:phoenix, "~> 1.3.0"},
      {:phoenix_pubsub, "~> 1.0"},
      {:phoenix_ecto, "~> 3.2"},
      {:gettext, "~> 0.11"},
      {:trangell_users_service, in_umbrella: true},
      {:cowboy, "~> 1.0"},
      {:plug_cowboy, "~> 1.0"}
    ]

I am using Docker, and my project is Json base and doesn’t have Html render.