Memory usage in module attributes

[Chris Jimison]

Silly Erlang/Elixir beam question.

If I have a module like so:

defmodule Foo do
  @data %{:foo => "foo", :bar => "bar"}

  def getData(), do: @data
end

spawn fn() ->
  x = Foo.getData()
  # Do something with x
  :timer.sleep(100000)
end

spawn fn()->
  x = Foo.getData()
  # Do something with x
  :timer.sleep(100000)
end

How many copies of 

%{:foo => "foo", :bar => "bar"}

are there in memory?  Does each process make a copy of the data in it's stack or do both process point to the same copy in some code space, etc.

Thanks!

-Chris

[Chris Jimison]

CRAP.  I posted here not reading that the topic should go to the general form.  I will move it to there and I am very sorry to bother folks!

[José Valim]

In any case, the answer is that literals in your code, such as module attributes, are stored in the literal pool. So it is only one copy until you modify it.

José Valim

www.plataformatec.com.br

Skype: jv.ptec

Founder and Director of R&D

--
You received this message because you are subscribed to the Google Groups "elixir-lang-core" group.
To unsubscribe from this group and stop receiving emails from it, send an email to elixir-lang-core+unsubscribe@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/elixir-lang-core/8759b998-e32a-4b9e-9e23-ab8c213c4524%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[Chris Jimison]

Thanks Jose you won me a beer :)  And once again I am very sorry for breaking form etiquette.

-Chris

To unsubscribe from this group and stop receiving emails from it, send an email to elixir-lang-co...@googlegroups.com.

[Michał Muskała]

Additionally the literal pool is excluded from regular garbage collection (since it never changes), so that's an additional efficiency gain.

Michał.

To unsubscribe from this group and stop receiving emails from it, send an email to elixir-lang-co...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/elixir-lang-core/CAGnRm4%2B_cr%3DqqL7A7RQE5nd-ebFORk_ocyGTT7FXrOwbXrN9bw%40mail.gmail.com.

[Chris Jimison]

Move this to the Elixir forms:

https://elixirforum.com/t/memory-usage-in-module-attributes/4176

To unsubscribe from this group and stop receiving emails from it, send an email to elixir-lang-co...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/elixir-lang-core/8759b998-e32a-4b9e-9e23-ab8c213c4524%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.