chore: Enhance indexer memory metrics (#9984)

apps/indexer/lib/indexer/memory/monitor.ex

@@ -13,6 +13,7 @@ defmodule Indexer.Memory.Monitor do
   import Indexer.Logger, only: [process: 1]
 
   alias Indexer.Memory.Shrinkable
+  alias Indexer.Prometheus.Instrumenter
 
   defstruct limit: 0,
             timer_interval: :timer.minutes(1),
@@ -68,6 +69,8 @@ defmodule Indexer.Memory.Monitor do
   def handle_info(:check, state) do
     total = :erlang.memory(:total)
 
+    set_metrics(state)
+
     shrunk_state =
       if memory_limit() < total do
         log_memory(%{limit: memory_limit(), total: total})
@@ -202,6 +205,35 @@ defmodule Indexer.Memory.Monitor do
     end)
   end
 
+  @megabytes_divisor 2 ** 20
+  defp set_metrics(%__MODULE__{shrinkable_set: shrinkable_set}) do
+    total_memory =
+      Enum.reduce(shrinkable_set, 0, fn pid, acc ->
+        memory = memory(pid) / @megabytes_divisor
+        name = name(pid)
+
+        Instrumenter.set_memory_consumed(name, memory)
+
+        acc + memory
+      end)
+
+    Instrumenter.set_memory_consumed(:total, total_memory)
+  end
+
+  defp name(pid) do
+    case Process.info(pid, :registered_name) do
+      {:registered_name, name} when is_atom(name) ->
+        name
+        |> to_string()
+        |> String.split(".")
+        |> Enum.slice(-2, 2)
+        |> Enum.join(".")
+
+      _ ->
+        nil
+    end
+  end
+
   defp shrinkable_memory_pairs(%__MODULE__{shrinkable_set: shrinkable_set}) do
     shrinkable_set
     |> Enum.map(fn pid -> {pid, memory(pid)} end)

apps/indexer/lib/indexer/prometheus/instrumenter.ex

@@ -35,6 +35,8 @@ defmodule Indexer.Prometheus.Instrumenter do
 
   @counter [name: :import_errors_count, help: "Number of database import errors"]
 
+  @gauge [name: :memory_consumed, labels: [:fetcher], help: "Amount of memory consumed by fetchers (MB)"]
+
   def block_full_process(time, fetcher) do
     Histogram.observe([name: :block_full_processing_duration_microseconds, labels: [fetcher]], time)
   end
@@ -58,4 +60,8 @@ defmodule Indexer.Prometheus.Instrumenter do
   def import_errors(error_count \\ 1) do
     Counter.inc([name: :import_errors_count], error_count)
   end
+
+  def set_memory_consumed(fetcher, memory) do
+    Gauge.set([name: :memory_consumed, labels: [fetcher]], memory)
+  end
 end