Merge branch 'rails5-gpg-permit-concurrent' into 'master'

Permit concurrent loads in gpg keychain mutex

See merge request gitlab-org/gitlab-ce!20894

changelogs/unreleased/rails5-gpg-permit-concurrent.yml

+---
+title: Permit concurrent loads in gpg keychain mutex
+merge_request: 20894
+author: Jasper Maes
+type: fixed

lib/gitlab/gpg.rb

@@ -71,8 +71,16 @@ module Gitlab
       if MUTEX.locked? && MUTEX.owned?
         optimistic_using_tmp_keychain(&block)
       else
-        MUTEX.synchronize do
-          optimistic_using_tmp_keychain(&block)
+        if Gitlab.rails5?
+          ActiveSupport::Dependencies.interlock.permit_concurrent_loads do
+            MUTEX.synchronize do
+              optimistic_using_tmp_keychain(&block)
+            end
+          end
+        else
+          MUTEX.synchronize do
+            optimistic_using_tmp_keychain(&block)
+          end
         end
       end
     end