Merge pull request #100 from VictorGaiva/fix/channel-process-gc

Adds an option to periodically run `:erlang.garbage_collect` on both the Channel and Transport processes

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 +149,14 @@ 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()
+    :erlang.garbage_collect(socket.transport_pid)
+    Process.send_after(self(), :gc, socket.assigns.absinthe.gc_interval)
+    {:noreply, socket}
+  end
+
+  def handle_info(_, socket) do
+    {:noreply, socket}
   end
 end

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
@@ -37,14 +49,16 @@ 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(
         "__absinthe__:*",
         Absinthe.Phoenix.Channel,
         assigns: %{
           __absinthe_schema__: unquote(schema),
-          __absinthe_pipeline__: unquote(pipeline)
+          __absinthe_pipeline__: unquote(pipeline),
+          __absinthe_gc_interval__: unquote(gc_interval)
         }
       )
     end