Elixir server

database_server.ex

defmodule DatabaseServer do

  def start do
    spawn(&loop/0)
  end

  # public API
  def run_async(server_pid, query_def) do
    send(server_pid, {:run_query, self, query_def})
  end

  def get_result do
    receive do
      { :query_result, result } -> result
    after 5000 ->
      { :error, :timeout }
    end
  end

  ## the server handle by executing
  ## the query and sending query messsage back
  defp loop do
    receive do
      ## executes run_query and send the result back
      {:run_query, caller, query_def} ->
        send(caller, {:query_result, run_query(query_def)})
    end
    loop
  end

  defp run_query(query_def) do
    :timer.sleep(2000)
    "#{query_def} result"
  end
end

## creating a pool of elixir workers
pool = 1..100 |> Enum.map(fn(_) -> DatabaseServer.start end) 

## randomly pick 5 workers to run 
1..5 |> 
Enum.each ( fn(query_def) -> 
  # selecting a random process
  server_pid = Enum.at(pool, :random.uniform(100) -1 )
  DatabaseServer.run_async(server_pid, query_def) 
end)

1..5 |> Enum.map (fn(_) -> DatabaseServer.get_result end)