SqlLab + Datasource "down" is a 500, but no error in UI

[wyndhblb]

Should a Datasource by down, SQLLab (the table/schemas parts) "spins forever" even though a 500 exception was thrown from the getting of a data source

(not sure if this is only limited to pyhive, but a 500 was certainly tossed to the client)

The UI should probably mention the "this failed".

[02/Nov/2016 23:17:08] "GET /databasetablesasync/api/read?_flt_0_id=4 HTTP/1.1" 500 -
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 2000, in __call__
    return self.wsgi_app(environ, start_response)
  File "/usr/local/lib/python2.7/dist-packages/werkzeug/contrib/fixers.py", line 152, in __call__
    return self.app(environ, start_response)
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1991, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1567, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1988, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1641, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1544, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1639, in full_dispatch_request
    rv = self.dispatch_request()
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1625, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/usr/local/lib/python2.7/dist-packages/flask_appbuilder/security/decorators.py", line 52, in wraps
    return f(self, *args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/flask_appbuilder/views.py", line 219, in api_read
    result = self.datamodel.get_values_json(lst, self.list_columns)
  File "/usr/local/lib/python2.7/dist-packages/flask_appbuilder/models/base.py", line 95, in get_values_json
    for item in self.get_values(lst, list_columns):
  File "/usr/local/lib/python2.7/dist-packages/flask_appbuilder/models/base.py", line 87, in get_values
    retdict[col] = self._get_attr_value(item, col)
  File "/usr/local/lib/python2.7/dist-packages/flask_appbuilder/models/base.py", line 44, in _get_attr_value
    return getattr(item, col)()
  File "/usr/local/lib/python2.7/dist-packages/caravel/models.py", line 496, in all_table_names
    return sorted(self.inspector.get_table_names(schema))
  File "/usr/local/lib/python2.7/dist-packages/caravel/models.py", line 493, in inspector
    return sqla.inspect(engine)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/inspection.py", line 63, in inspect
    ret = reg(subject)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/reflection.py", line 139, in _insp
    return Inspector.from_engine(bind)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/reflection.py", line 135, in from_engine
    return Inspector(bind)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/reflection.py", line 109, in __init__
    bind.connect().close()
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 2018, in connect
    return self._connection_cls(self, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 72, in __init__
    if connection is not None else engine.raw_connection()
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 2104, in raw_connection
    self.pool.unique_connection, _connection)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 2074, in _wrap_pool_connect
    return fn()
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 318, in unique_connection
    return _ConnectionFairy._checkout(self)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 713, in _checkout
    fairy = _ConnectionRecord.checkout(pool)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 480, in checkout
    rec = pool._do_get()
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 1060, in _do_get
    self._dec_overflow()
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/util/langhelpers.py", line 60, in __exit__
    compat.reraise(exc_type, exc_value, exc_tb)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 1057, in _do_get
    return self._create_connection()
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 323, in _create_connection
    return _ConnectionRecord(self)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 449, in __init__
    self.connection = self.__connect()
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/pool.py", line 607, in __connect
    connection = self.__pool._invoke_creator(self)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/strategies.py", line 97, in connect
    return dialect.connect(*cargs, **cparams)
  File "/usr/local/lib/python2.7/dist-packages/sqlalchemy/engine/default.py", line 385, in connect
    return self.dbapi.connect(*cargs, **cparams)
  File "/usr/local/lib/python2.7/dist-packages/pyhive/hive.py", line 63, in connect
    return Connection(*args, **kwargs)
  File "/usr/local/lib/python2.7/dist-packages/pyhive/hive.py", line 104, in __init__
    self._transport.open()
  File "/usr/local/lib/python2.7/dist-packages/thrift_sasl/__init__.py", line 61, in open
    self._trans.open()
  File "/usr/local/lib/python2.7/dist-packages/thrift/transport/TSocket.py", line 101, in open
    message=message)

Caravel version

latest (0.12.0)

[msyafiqmazli]

I faced same issue like above.

[mistercrunch]

This PR should help #2709