healthcheck: report real amount of memory allocated by beam

as opposed to memory currently in use

CHANGELOG.md

@@ -42,6 +42,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased (patch)]
 
+### Fixed
+- Healthcheck reporting the number of memory currently used, rather than allocated in total
+
 ## [2.0.3] - 2020-05-02
 
 ### Security

lib/pleroma/healthcheck.ex

@@ -29,7 +29,7 @@ defmodule Pleroma.Healthcheck do
   @spec system_info() :: t()
   def system_info do
     %Healthcheck{
-      memory_used: Float.round(:erlang.memory(:total) / 1024 / 1024, 2)
+      memory_used: Float.round(:recon_alloc.memory(:allocated) / 1024 / 1024, 2)
     }
     |> assign_db_info()
     |> assign_job_queue_stats()