Controller ack POST ASAP and pass data to another function for processing

Just spawn a new process to do the work in the background?

If you want to supervise the processing, you can employ a Task.Supervisor and start children in your controller.

Thanks for this, @dimitarvp!
I did not know about this. I was able to read some of your other answers to similar questions and get a solution in place.

In case it’s useful for anyone landing here later…
I ended up making my controller like this:

def send_msg(conn, params) do
    # Use Task to handle send msg in background
    # while returning ASAP
    Task.start_link(fn ->
      IO.puts "I am running in a task"
      sendMsg(params)
    end)

    IO.puts("EXIT send_msg")
    json(conn)
  end

and the logs show “EXIT send_msg” before “I’m running in a task.” This is great for me because I need the API call to “fire and forget”, as the Task documentation describes:

We encourage developers to rely on supervised tasks as much as possible… Here is a summary:

• Use Task.Supervisor.start_child/2 to start a fire-and-forget task and you don’t care about its results nor about if it completes successfully
• Use Task.Supervisor.async/2 + Task.await/2 allows you to execute tasks concurrently and retrieve its result. If the task fails, the caller will also fail
• Use Task.Supervisor.async_nolink/2 + Task.yield/2 + Task.shutdown/2 allows you to execute tasks concurrently and retrieve their results or the reason they failed within a given time frame. If the task fails, the caller won’t fail: you will receive the error reason either on yield or shutdown

and here:

By default, the functions Task.start and Task.start_link are for fire-and-forget tasks, where you don’t care about the results or if it completes successfully or not.