Ignore io response messages when logging (#1997)

lib/livebook/runtime/erl_dist.ex

@@ -39,6 +39,7 @@ defmodule Livebook.Runtime.ErlDist do
       Livebook.Runtime.ErlDist.IOForwardGL,
       Livebook.Runtime.ErlDist.LoggerGLBackend,
       Livebook.Runtime.ErlDist.LoggerGLHandler,
+      Livebook.Runtime.ErlDist.Sink,
       Livebook.Runtime.ErlDist.SmartCellGL
     ]
   end

lib/livebook/runtime/erl_dist/logger_gl_handler.ex

@@ -13,7 +13,8 @@ defmodule Livebook.Runtime.ErlDist.LoggerGLHandler do
   end
 
   def async_io(device, output) when is_pid(device) do
-    send(device, {:io_request, self(), make_ref(), {:put_chars, :unicode, output}})
+    reply_to = Livebook.Runtime.ErlDist.Sink.pid()
+    send(device, {:io_request, reply_to, make_ref(), {:put_chars, :unicode, output}})
   end
 
   @doc false

lib/livebook/runtime/erl_dist/node_manager.ex

@@ -98,6 +98,8 @@ defmodule Livebook.Runtime.ErlDist.NodeManager do
 
     # TODO: remove logger backend once we require Elixir v1.15
     if Code.ensure_loaded?(Logger) and function_exported?(Logger, :add_handlers, 1) do
+      {:ok, _pid} = Livebook.Runtime.ErlDist.Sink.start_link()
+
       :logger.add_handler(:livebook_gl_handler, Livebook.Runtime.ErlDist.LoggerGLHandler, %{
         formatter: Logger.Formatter.new(),
         filters: [

lib/livebook/runtime/erl_dist/sink.ex

@@ -0,0 +1,35 @@
+defmodule Livebook.Runtime.ErlDist.Sink do
+  @moduledoc false
+
+  # An idle process that ignores all incoming messages.
+
+  use GenServer
+
+  @name __MODULE__
+
+  @doc """
+  Starts the process.
+  """
+  @spec start_link() :: GenServer.on_start()
+  def start_link() do
+    GenServer.start_link(__MODULE__, {}, name: @name)
+  end
+
+  @doc """
+  Returns pid of the global sink process.
+  """
+  @spec pid() :: pid()
+  def pid() do
+    Process.whereis(@name)
+  end
+
+  @impl true
+  def init({}) do
+    {:ok, {}}
+  end
+
+  @impl true
+  def handle_info(_message, state) do
+    {:noreply, state}
+  end
+end