From 31f1ec59a7cf7517cd5935ef3af540aceba07bb3 Mon Sep 17 00:00:00 2001
From: Lin Jen-Shin <godfat@godfat.org>
Date: Wed, 7 Feb 2018 22:44:05 +0800
Subject: Release the entire env

---
 config.ru                                            |  2 +-
 lib/gitlab/middleware/release_controller.rb          |  9 ---------
 lib/gitlab/middleware/release_env.rb                 | 14 ++++++++++++++
 .../lib/gitlab/middleware/release_controller_spec.rb | 20 --------------------
 spec/lib/gitlab/middleware/release_env_spec.rb       | 20 ++++++++++++++++++++
 5 files changed, 35 insertions(+), 30 deletions(-)
 delete mode 100644 lib/gitlab/middleware/release_controller.rb
 create mode 100644 lib/gitlab/middleware/release_env.rb
 delete mode 100644 spec/lib/gitlab/middleware/release_controller_spec.rb
 create mode 100644 spec/lib/gitlab/middleware/release_env_spec.rb

diff --git a/config.ru b/config.ru
index c4bef72308e..7b15939c6ff 100644
--- a/config.ru
+++ b/config.ru
@@ -23,6 +23,6 @@ warmup do |app|
 end
 
 map ENV['RAILS_RELATIVE_URL_ROOT'] || "/" do
-  use Gitlab::ReleaseController
+  use Gitlab::Middleware::ReleaseEnv
   run Gitlab::Application
 end
diff --git a/lib/gitlab/middleware/release_controller.rb b/lib/gitlab/middleware/release_controller.rb
deleted file mode 100644
index a21d718d51c..00000000000
--- a/lib/gitlab/middleware/release_controller.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-module Gitlab
-  module Middleware
-    ReleaseController = Struct.new(:app) do
-      def call(env)
-        app.call(env).tap { env.delete('action_controller.instance') }
-      end
-    end
-  end
-end
diff --git a/lib/gitlab/middleware/release_env.rb b/lib/gitlab/middleware/release_env.rb
new file mode 100644
index 00000000000..f8d0a135965
--- /dev/null
+++ b/lib/gitlab/middleware/release_env.rb
@@ -0,0 +1,14 @@
+module Gitlab
+  module Middleware
+    # Some of middleware would hold env for no good reason even after the
+    # request had already been processed, and we could not garbage collect
+    # them due to this. Put this middleware as the first middleware so that
+    # it would clear the env after the request is done, allowing GC gets a
+    # chance to release memory for the last request.
+    ReleaseEnv = Struct.new(:app) do
+      def call(env)
+        app.call(env).tap { env.clear }
+      end
+    end
+  end
+end
diff --git a/spec/lib/gitlab/middleware/release_controller_spec.rb b/spec/lib/gitlab/middleware/release_controller_spec.rb
deleted file mode 100644
index 854bac6e751..00000000000
--- a/spec/lib/gitlab/middleware/release_controller_spec.rb
+++ /dev/null
@@ -1,20 +0,0 @@
-require 'spec_helper'
-
-describe Gitlab::Middleware::ReleaseController do
-  let(:inner_app) { double(:app) }
-  let(:app) { described_class.new(inner_app) }
-  let(:env) { { 'action_controller.instance' => 'something' } }
-
-  before do
-    expect(inner_app).to receive(:call).with(env).and_return('yay')
-  end
-
-  describe '#call' do
-    it 'calls the app and delete the controller' do
-      result = app.call(env)
-
-      expect(result).to eq('yay')
-      expect(env).to be_empty
-    end
-  end
-end
diff --git a/spec/lib/gitlab/middleware/release_env_spec.rb b/spec/lib/gitlab/middleware/release_env_spec.rb
new file mode 100644
index 00000000000..657b705502a
--- /dev/null
+++ b/spec/lib/gitlab/middleware/release_env_spec.rb
@@ -0,0 +1,20 @@
+require 'spec_helper'
+
+describe Gitlab::Middleware::ReleaseEnv do
+  let(:inner_app) { double(:app) }
+  let(:app) { described_class.new(inner_app) }
+  let(:env) { { 'action_controller.instance' => 'something' } }
+
+  before do
+    expect(inner_app).to receive(:call).with(env).and_return('yay')
+  end
+
+  describe '#call' do
+    it 'calls the app and delete the controller' do
+      result = app.call(env)
+
+      expect(result).to eq('yay')
+      expect(env).to be_empty
+    end
+  end
+end
-- 
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