[AIRFLOW-2776] Compress tree view JSON

The tree view generates JSON that can be massive
for bigger DAGs,
up to 10s of MBs. The JSON is currently
prettified, which both
takes up more CPU time during serialization, and
slows down
everything else that uses it. Considering the JSON
is only
meant to be used programmatically, this is an easy
win

Closes #3620 from abdul-stripe/smaller-tree-view-
json

airflow/www/views.py

@@ -1477,7 +1477,8 @@ class Airflow(BaseView):
                 for d in dates],
         }
 
-        data = json.dumps(data, indent=4, default=json_ser)
+        # minimize whitespace as this can be huge for bigger dags
+        data = json.dumps(data, default=json_ser, separators=(',', ':'))
         session.commit()
 
         form = DateTimeWithNumRunsForm(data={'base_date': max_date,

airflow/www_rbac/views.py

@@ -1208,7 +1208,8 @@ class Airflow(AirflowBaseView):
                 for d in dates],
         }
 
-        data = json.dumps(data, indent=4, default=json_ser)
+        # minimize whitespace as this can be huge for bigger dags
+        data = json.dumps(data, default=json_ser, separators=(',', ':'))
         session.commit()
 
         form = DateTimeWithNumRunsForm(data={'base_date': max_date,