Use Gitlab::Database.with_connection_pool from !9192

db/post_migrate/20170206040400_remove_inactive_default_email_services.rb

@@ -6,7 +6,7 @@ class RemoveInactiveDefaultEmailServices < ActiveRecord::Migration
   disable_ddl_transaction!
 
   def up
-    pool = create_connection_pool
+    Gitlab::Database.with_connection_pool(2) do |pool|
       threads = []
 
       threads << Thread.new do
@@ -32,27 +32,10 @@ class RemoveInactiveDefaultEmailServices < ActiveRecord::Migration
       end
 
       threads.each(&:join)
-    pool.disconnect!
+    end
   end
 
   def down
     # Nothing can be done to restore the records
   end
-
-  private
-
-  def create_connection_pool
-    # See activerecord-4.2.7.1/lib/active_record/connection_adapters/connection_specification.rb
-    env = Rails.env
-    original_config = ActiveRecord::Base.configurations
-    env_config = original_config[env].merge('pool' => 2)
-    config = original_config.merge(env => env_config)
-
-    spec =
-      ActiveRecord::
-        ConnectionAdapters::
-        ConnectionSpecification::Resolver.new(config).spec(env.to_sym)
-
-    ActiveRecord::ConnectionAdapters::ConnectionPool.new(spec)
-  end
 end

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20170204181513) do
+ActiveRecord::Schema.define(version: 20170210075922) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"