Revert "Parallelize template rendering"

This reverts commit 1ad71592adb47762287aec8c36d0fca565c38362.

Since it had no limit on the number on concurrent processes it OOM killed
instances while rendering hellthreads. When I tried introducing a
concurrency limit with Task.async_stream/manual folds it lead to about 3 times
worse performance on threads larger than 1000 activities (we are talking
30s vs 1.2 minutes), I think this is not worth the about 1.5 times
performance increase on smaller threads when using it.

2 files changed, 3 insertions, 19 deletions

diff --git a/lib/pleroma/web/mastodon_api/views/status_view.ex b/lib/pleroma/web/mastodon_api/views/status_view.ex
index e71083b91..b6a3431f9 100644
--- a/lib/pleroma/web/mastodon_api/views/status_view.ex
+++ b/lib/pleroma/web/mastodon_api/views/status_view.ex
@@ -73,14 +73,12 @@ defmodule Pleroma.Web.MastodonAPI.StatusView do
 
   def render("index.json", opts) do
     replied_to_activities = get_replied_to_activities(opts.activities)
-    parallel = unless is_nil(opts[:parallel]), do: opts[:parallel], else: true
 
     opts.activities
     |> safe_render_many(
       StatusView,
       "status.json",
-      Map.put(opts, :replied_to_activities, replied_to_activities),
-      parallel
+      Map.put(opts, :replied_to_activities, replied_to_activities)
     )
   end
 
diff --git a/lib/pleroma/web/web.ex b/lib/pleroma/web/web.ex
index bfb6c7287..687346554 100644
--- a/lib/pleroma/web/web.ex
+++ b/lib/pleroma/web/web.ex
@@ -66,23 +66,9 @@ defmodule Pleroma.Web do
       end
 
       @doc """
-      Same as `render_many/4` but wrapped in rescue block and parallelized (unless disabled by passing false as a fifth argument).
+      Same as `render_many/4` but wrapped in rescue block.
       """
-      def safe_render_many(collection, view, template, assigns \\ %{}, parallel \\ true)
-
-      def safe_render_many(collection, view, template, assigns, true) do
-        Enum.map(collection, fn resource ->
-          Task.async(fn ->
-            as = Map.get(assigns, :as) || view.__resource__
-            assigns = Map.put(assigns, as, resource)
-            safe_render(view, template, assigns)
-          end)
-        end)
-        |> Enum.map(&Task.await(&1, :infinity))
-        |> Enum.filter(& &1)
-      end
-
-      def safe_render_many(collection, view, template, assigns, false) do
+      def safe_render_many(collection, view, template, assigns \\ %{}) do
         Enum.map(collection, fn resource ->
           as = Map.get(assigns, :as) || view.__resource__
           assigns = Map.put(assigns, as, resource)