diff --git a/airflow/www/app.py b/airflow/www/app.py
index 40386fd6bb..3187686a16 100644
--- a/airflow/www/app.py
+++ b/airflow/www/app.py
@@ -43,6 +43,7 @@ if AUTHENTICATE is False:
 
 dagbag = models.DagBag(conf.get('core', 'DAGS_FOLDER'))
 session = Session()
+settings.pessimistic_connection_handling()
 
 app = Flask(__name__)
 login_manager.init_app(app)
diff --git a/requirements.txt b/requirements.txt
index 0821178509..9eec6d2d14 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,6 +4,7 @@ flake8
 flask
 flask-admin
 flask-bootstrap
+flask-cache
 hive-thrift-py
 ipython[all]
 jinja2