[database] Encode before writing to file

beat/backend/python/database.py

@@ -135,7 +135,8 @@ class Runner(object):
             os.makedirs(os.path.dirname(filename))
 
         with open(filename, 'wb') as f:
-            simplejson.dump(objs, f, cls=utils.NumpyJSONEncoder)
+            data = simplejson.dumps(objs, cls=utils.NumpyJSONEncoder)
+            f.write(data.encode('utf-8'))
 
 
     def setup(self, filename, start_index=None, end_index=None, pack=True):