Google App Engine Application Error 5

I frequently get this Application error. What does this mean ?

File "/base/data/home/apps/0xxopdp/10.347467753731922开发者_StackOverflow中文版836/matrices.py", line 215, in insert_into_db
    obj.put()
  File "/base/python_runtime/python_lib/versions/1/google/appengine/ext/db/__init__.py", line 895, in put
    return datastore.Put(self._entity, config=config)
  File "/base/python_runtime/python_lib/versions/1/google/appengine/api/datastore.py", line 404, in Put
    return _GetConnection().async_put(config, entities, extra_hook).get_result()
  File "/base/python_runtime/python_lib/versions/1/google/appengine/datastore/datastore_rpc.py", line 601, in get_result
    self.check_success()
  File "/base/python_runtime/python_lib/versions/1/google/appengine/datastore/datastore_rpc.py", line 572, in check_success
    rpc.check_success()
  File "/base/python_runtime/python_lib/versions/1/google/appengine/api/apiproxy_stub_map.py", line 502, in check_success
    self.__rpc.CheckSuccess()
  File "/base/python_runtime/python_lib/versions/1/google/appengine/api/apiproxy_rpc.py", line 126, in CheckSuccess
    raise self.exception
ApplicationError: ApplicationError: 5

I do make many calls to the datastore. What caused this problem ?

The ApplicationError:5 message tipically indicates a Timeout error.

The error is raised by the datastore API, so your application is probably trying to make more than the allowed 5 writes per seconds to db.

I would recommend you to read this insightful article about Handling Datastore Errors that explains very well the possible timeout 's causes and how to deal with them.