From 1518b46fa5658e163351f312c501d8e7cb6a9b2f Mon Sep 17 00:00:00 2001
From: Victor Gaiva <13839490+VictorGaiva@users.noreply.github.com>
Date: Wed, 13 Dec 2023 14:53:54 -0300
Subject: [PATCH 1/3] fix: Adds the option to periodically garbage collect the
 channel process

---
 lib/absinthe/phoenix/channel.ex | 19 ++++++++++++++++---
 lib/absinthe/phoenix/socket.ex  | 16 +++++++++++++++-
 2 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/lib/absinthe/phoenix/channel.ex b/lib/absinthe/phoenix/channel.ex
index 5e32a8b..3d10bb8 100644
--- a/lib/absinthe/phoenix/channel.ex
+++ b/lib/absinthe/phoenix/channel.ex
@@ -17,6 +17,7 @@ defmodule Absinthe.Phoenix.Channel do
   def join("__absinthe__:control", _, socket) do
     schema = socket.assigns[:__absinthe_schema__]
     pipeline = socket.assigns[:__absinthe_pipeline__]
+    gc_interval = socket.assigns[:__absinthe_gc_interval__]
 
     absinthe_config = Map.get(socket.assigns, :absinthe, %{})
 
@@ -32,7 +33,13 @@ defmodule Absinthe.Phoenix.Channel do
       |> Map.update(:schema, schema, & &1)
 
     absinthe_config =
-      Map.put(absinthe_config, :pipeline, pipeline || {__MODULE__, :default_pipeline})
+      absinthe_config
+      |> Map.put(:pipeline, pipeline || {__MODULE__, :default_pipeline})
+      |> Map.put(:gc_interval, gc_interval)
+
+    unless gc_interval == nil do
+      Process.send_after(self(), :gc, gc_interval)
+    end
 
     socket = socket |> assign(:absinthe, absinthe_config)
     {:ok, socket}
@@ -142,7 +149,13 @@ defmodule Absinthe.Phoenix.Channel do
     |> Absinthe.Pipeline.for_document(options)
   end
 
-  def handle_info(_, state) do
-    {:noreply, state}
+  def handle_info(:gc, socket) do
+    :erlang.garbage_collect()
+    Process.send_after(self(), :gc, socket.assigns.absinthe.gc_interval)
+    {:noreply, socket}
+  end
+
+  def handle_info(_, socket) do
+    {:noreply, socket}
   end
 end
diff --git a/lib/absinthe/phoenix/socket.ex b/lib/absinthe/phoenix/socket.ex
index 2508f86..052ef03 100644
--- a/lib/absinthe/phoenix/socket.ex
+++ b/lib/absinthe/phoenix/socket.ex
@@ -25,6 +25,18 @@ defmodule Absinthe.Phoenix.Socket do
   ## Phoenix 1.2
 
   If you're on Phoenix 1.2 see `put_schema/2`.
+
+  ## Garbage Collection
+
+  In some workloads, the Channel Process responsible for handling [subscriptions may accumulate
+  some gargage](https://elixirforum.com/t/why-does-garbage-collection-not-work-as-intended/50613/2), that is not being collected by the Erlang VM. A workaround for this is to instruct
+  the process to periodically tell the VM to collect its garbage. This can be done by setting the
+  `gc_interval`.
+
+        use Absinthe.Phoenix.Socket,
+          schema: MyApp.Web.Schema,
+          gc_interval: 10_000
+
   """
 
   defmacro __using__(opts) do
@@ -37,6 +49,7 @@ defmodule Absinthe.Phoenix.Socket do
 
     schema = Keyword.get(opts, :schema)
     pipeline = Keyword.get(opts, :pipeline)
+    gc_interval = Keyword.get(opts, :gc_interval)
 
     quote do
       channel(
@@ -44,7 +57,8 @@ defmodule Absinthe.Phoenix.Socket do
         Absinthe.Phoenix.Channel,
         assigns: %{
           __absinthe_schema__: unquote(schema),
-          __absinthe_pipeline__: unquote(pipeline)
+          __absinthe_pipeline__: unquote(pipeline),
+          __absinthe_gc_interval: unquote(gc_interval)
         }
       )
     end

From 404bb2025b407bb2bda5d355167ebd2cc6b637a3 Mon Sep 17 00:00:00 2001
From: Victor Gaiva <13839490+VictorGaiva@users.noreply.github.com>
Date: Thu, 14 Dec 2023 09:50:48 -0300
Subject: [PATCH 2/3] fix: Add GC to transport process

---
 lib/absinthe/phoenix/channel.ex | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/absinthe/phoenix/channel.ex b/lib/absinthe/phoenix/channel.ex
index 3d10bb8..96c0d97 100644
--- a/lib/absinthe/phoenix/channel.ex
+++ b/lib/absinthe/phoenix/channel.ex
@@ -151,6 +151,7 @@ defmodule Absinthe.Phoenix.Channel do
 
   def handle_info(:gc, socket) do
     :erlang.garbage_collect()
+    :erlang.garbage_collect(socket.transport_pid)
     Process.send_after(self(), :gc, socket.assigns.absinthe.gc_interval)
     {:noreply, socket}
   end

From cdf34983e429eeb5c1d5372a33cf683323fba24b Mon Sep 17 00:00:00 2001
From: Victor Gaiva <13839490+VictorGaiva@users.noreply.github.com>
Date: Thu, 14 Dec 2023 12:39:35 -0300
Subject: [PATCH 3/3] fix: Fix assign key

---
 lib/absinthe/phoenix/socket.ex | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/absinthe/phoenix/socket.ex b/lib/absinthe/phoenix/socket.ex
index 052ef03..9f46655 100644
--- a/lib/absinthe/phoenix/socket.ex
+++ b/lib/absinthe/phoenix/socket.ex
@@ -58,7 +58,7 @@ defmodule Absinthe.Phoenix.Socket do
         assigns: %{
           __absinthe_schema__: unquote(schema),
           __absinthe_pipeline__: unquote(pipeline),
-          __absinthe_gc_interval: unquote(gc_interval)
+          __absinthe_gc_interval__: unquote(gc_interval)
         }
       )
     end