Class Pool

lib/sqlalchemy/pool/base.py:156–469

Abstract base class for connection pools.

class Pool(log.Identified, event.EventTarget):
    """Abstract base class for connection pools."""

    dispatch: dispatcher[Pool]
    echo: log._EchoFlagType

    _orig_logging_name: Optional[str]
    _dialect: Union[_ConnDialect, Dialect] = _ConnDialect()
    _creator_arg: Union[_CreatorFnType, _CreatorWRecFnType]
    _invoke_creator: _CreatorWRecFnType
    _invalidate_time: float

    def __init__(
        self,
        creator: Union[_CreatorFnType, _CreatorWRecFnType],
        recycle: int = -1,
        echo: log._EchoFlagType = None,
        logging_name: Optional[str] = None,
        reset_on_return: _ResetStyleArgType = True,
        events: Optional[List[Tuple[_ListenerFnType, str]]] = None,
        dialect: Optional[Union[_ConnDialect, Dialect]] = None,
        pre_ping: bool = False,
        _dispatch: Optional[_DispatchCommon[Pool]] = None,
    ):
        """
        Construct a Pool.

        :param creator: a callable function that returns a DB-API
          connection object.  The function will be called with
          parameters.

        :param recycle: If set to a value other than -1, number of
          seconds between connection recycling, which means upon
          checkout, if this timeout is surpassed the connection will be
          closed and replaced with a newly opened connection. Defaults to -1.

        :param logging_name:  String identifier which will be used within
          the "name" field of logging records generated within the
          "sqlalchemy.pool" logger. Defaults to a hexstring of the object's
          id.

        :param echo: if True, the connection pool will log
         informational output such as when connections are invalidated
         as well as when connections are recycled to the default log handler,
         which defaults to ``sys.stdout`` for output..   If set to the string
         ``"debug"``, the logging will include pool checkouts and checkins.

         The :paramref:`_pool.Pool.echo` parameter can also be set from the
         :func:`_sa.create_engine` call by using the
         :paramref:`_sa.create_engine.echo_pool` parameter.

         .. seealso::

             :ref:`dbengine_logging` - further detail on how to configure
             logging.

        :param reset_on_return: Determine steps to take on
         connections as they are returned to the pool, which were