sqlalchemy.pool.impl.SingletonThreadPool

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 not otherwise handled by a :class:`_engine.Connection`. Available from :func:`_sa.create_engine` via the :paramref:`_sa.create_engine.pool_reset_on_return` parameter. :paramref:`_pool.Pool.reset_on_return` can have any of these values: * ``"rollback"`` - call rollback() on the connection, to release locks and transaction resources. This is the default value. The vast majority of use cases should leave this value set. * ``"commit"`` - call commit() on the connection, to release locks and transaction resources. A commit here may be desirable for databases that cache query plans if a commit is emitted, such as Microsoft SQL Server. However, this value is more dangerous than 'rollback' because any data changes present on the transaction are committed unconditionally. * ``None`` - don't do anything on the connection. This setting may be appropriate if the database / DBAPI works in pure "autocommit" mode at all times, or if a custom reset handler is established using the :meth:`.PoolEvents.reset` event handler. * ``True`` - same as 'rollback', this is here for backwards compatibility. * ``False`` - same as None, this is here for backwards compatibility. For further customization of reset on return, the :meth:`.PoolEvents.reset` event hook may be used which can perform any connection activity desired on reset. .. seealso:: :ref:`pool_reset_on_return` :meth:`.PoolEvents.reset` :param events: a list of 2-tuples, each of the form ``(callable, target)`` which will be passed to :func:`.event.listen` upon construction. Provided here so that event listeners can be assigned via :func:`_sa.create_engine` before dialect-level listeners are applied. :param dialect: a :class:`.Dialect` that will handle the job of calling rollback(), close(), or commit() on DBAPI connections. If omitted, a built-in "stub" dialect is used. Applications that make use of :func:`_sa.create_engine` should not use this parameter as it is handled by the engine creation strategy. .. versionadded:: 1.1 - ``dialect`` is now a public parameter to the :class:`_pool.Pool`. :param pre_ping: if True, the pool will emit a "ping" (typically "SELECT 1", but is dialect-specific) on the connection upon checkout, to test if the connection is alive or not. If not, the connection is transparently re-connected and upon success, all other pooled connections established prior to that timestamp are invalidated. Requires that a dialect is passed as well to interpret the disconnection error. .. versionadded:: 1.2

Return a DBAPI connection from the pool. The connection is instrumented such that when its ``close()`` method is called, the connection will be returned to the pool.

Dispose of this pool.

Return a new :class:`_pool.Pool`, of the same class as this one and configured with identical creation arguments. This method is used in conjunction with :meth:`dispose` to close out an entire :class:`_pool.Pool` and create a new one in its place.

Undocumented