I have a question regarding polling strategies.

I generally like doing GenServer + Process.send_after because it’s more intuitive for me.

Lately I came across two Internet sources that do this:

defmodule Example.BitcoinPriceUpdater do
  use Task
  def start_link(_arg) do
    Task.start_link(&poll/0)
  end
  def poll() do
    receive do
    after
      60_000 ->
        get_price()
        poll()
    end
  end
  defp get_price() do
    # Call API & Persist
    IO.puts "To the moon!"
  end
end

(excerpt: Periodic tasks with Elixir. No more Googling for Cron syntax | by Ville | Medium)

And also the same usage in JokenJwks library:

      use Task, restart: :transient
...
      @doc false
      def poll(opts) do
        interval = opts[:time_interval]

        receive do
        after
          interval ->
            _ = check_fetch(opts)
            poll(opts)
        end
      end

Is there any "gotcha"s when you use Task-based polling under Supervisor?

Specifically, at work I had the JokenJwks.DefaultStrategyTemplate used (via use) in my Phoenix application, but I was able to crash the module based Task when I ran a custom Mix Task, while the app was running.

The custom Mix Task did not even remotely use the same code base.
Setting :logger config to:

config :logger,
  level: :debug,
  handle_sasl_reports: true

Allowed me to see that when the process crashed, resources were:

• Heap Size: 29_000
• Reduction was around 440_000. Isn’t that pretty high? I still don’t know how to guage reduction units…

When I do a Process.monitor() + receive, I get instantaneous DOWN messages, so I am even more puzzled.

Frankly, I can’t quite grasp how a recursing poll() in a use Task, under Supervisor would be running - so is this like a long-running process?

Now if we talk about doing a GenServer + polling via recursive Process.send_after, I totally get that right off the bat - I know what’s happening.

So I wanted to ask - is there a case where one would want to use receive + after polling with use Task? Besides the fact that it might look “simpler”, especially when the intention is for a long-running poll?

Thanks in advance.