Is `:erlang.process_info(:pid, :message_queue_len)` a heavy operation?

[josevalim]

@ericmj

Can you elaborate on what you mean by “blocking”? All function calls in Elixir are blocking in some sense, so what does it block?

Process.info, when called from an external process, puts a lock on the process being “infoed”. Therefore, it is super safe when calling with self() but not from an external one.