sqlalchemy.pool.impl.QueuePool

class documentation

class QueuePool(Pool): (source)

Known subclasses: sqlalchemy.pool.impl.AsyncAdaptedQueuePool

A :class:`_pool.Pool` that imposes a limit on the number of open connections. :class:`.QueuePool` is the default pooling implementation used for all :class:`_engine.Engine` objects, unless the SQLite dialect is in use.

Method	`__init__`	Construct a QueuePool.
Method	`checkedin`	Undocumented
Method	`checkedout`	Undocumented
Method	`dispose`	Dispose of this pool.
Method	`overflow`	Undocumented
Method	`recreate`	Return a new :class:`_pool.Pool`, of the same class as this one and configured with identical creation arguments.
Method	`size`	Undocumented
Method	`status`	Undocumented
Method	`timeout`	Undocumented
Method	`_dec_overflow`	Undocumented
Method	`_do_get`	Implementation for :meth:`get`, supplied by subclasses.
Method	`_do_return_conn`	Implementation for :meth:`return_conn`, supplied by subclasses.
Method	`_inc_overflow`	Undocumented
Class Variable	`_is_asyncio`	Undocumented
Instance Variable	`_max_overflow`	Undocumented
Instance Variable	`_overflow`	Undocumented
Instance Variable	`_overflow_lock`	Undocumented
Instance Variable	`_pool`	Undocumented
Instance Variable	`_timeout`	Undocumented

Inherited from Pool:

Method	`connect`	Return a DBAPI connection from the pool.
Class Variable	`dispatch`	Undocumented
Instance Variable	`echo`	Undocumented
Instance Variable	`logging_name`	Undocumented
Method	`_close_connection`	Undocumented
Method	`_create_connection`	Called by subclasses to create a new ConnectionRecord.
Method	`_creator.deleter`	Undocumented
Method	`_creator.setter`	Undocumented
Method	`_invalidate`	Mark all connections established within the generation of the given connection as invalidated.
Method	`_return_conn`	Given a _ConnectionRecord, return it to the :class:`_pool.Pool`.
Method	`_should_wrap_creator`	Detect if creator accepts a single argument, or is sent as a legacy style no-arg function.
Instance Variable	`_creator_arg`	Undocumented
Instance Variable	`_dialect`	Undocumented
Instance Variable	`_invalidate_time`	Undocumented
Instance Variable	`_invoke_creator`	Undocumented
Instance Variable	`_orig_logging_name`	Undocumented
Instance Variable	`_pre_ping`	Undocumented
Instance Variable	`_recycle`	Undocumented
Instance Variable	`_reset_on_return`	Undocumented
Property	`_creator`	Undocumented

Inherited from Identified (via Pool):

Class Variable	`__slots__`	Undocumented
Class Variable	`logger`	Undocumented
Method	`_should_log_debug`	Undocumented
Method	`_should_log_info`	Undocumented
Class Variable	`_echo`	Undocumented

def __init__(self, creator: Union[_CreatorFnType, _CreatorWRecFnType], pool_size: int = 5, max_overflow: int = 10, timeout: float = 30.0, use_lifo: bool = False, **kw: Any): (source) ¶

overrides sqlalchemy.pool.base.Pool.__init__

Construct a QueuePool. :param creator: a callable function that returns a DB-API connection object, same as that of :paramref:`_pool.Pool.creator`. :param pool_size: The size of the pool to be maintained, defaults to 5. This is the largest number of connections that will be kept persistently in the pool. Note that the pool begins with no connections; once this number of connections is requested, that number of connections will remain. ``pool_size`` can be set to 0 to indicate no size limit; to disable pooling, use a :class:`~sqlalchemy.pool.NullPool` instead. :param max_overflow: The maximum overflow size of the pool. When the number of checked-out connections reaches the size set in pool_size, additional connections will be returned up to this limit. When those additional connections are returned to the pool, they are disconnected and discarded. It follows then that the total number of simultaneous connections the pool will allow is pool_size + `max_overflow`, and the total number of "sleeping" connections the pool will allow is pool_size. `max_overflow` can be set to -1 to indicate no overflow limit; no limit will be placed on the total number of concurrent connections. Defaults to 10. :param timeout: The number of seconds to wait before giving up on returning a connection. Defaults to 30.0. This can be a float but is subject to the limitations of Python time functions which may not be reliable in the tens of milliseconds. :param use_lifo: use LIFO (last-in-first-out) when retrieving connections instead of FIFO (first-in-first-out). Using LIFO, a server-side timeout scheme can reduce the number of connections used during non-peak periods of use. When planning for server-side timeouts, ensure that a recycle or pre-ping strategy is in use to gracefully handle stale connections. .. versionadded:: 1.3 .. seealso:: :ref:`pool_use_lifo` :ref:`pool_disconnects` :param \**kw: Other keyword arguments including :paramref:`_pool.Pool.recycle`, :paramref:`_pool.Pool.echo`, :paramref:`_pool.Pool.reset_on_return` and others are passed to the :class:`_pool.Pool` constructor.

def checkedin(self) -> int: (source) ¶

Undocumented

def checkedout(self) -> int: (source) ¶

Undocumented

def dispose(self): (source) ¶

overrides sqlalchemy.pool.base.Pool.dispose

Dispose of this pool. This method leaves the possibility of checked-out connections remaining open, as it only affects connections that are idle in the pool. .. seealso:: :meth:`Pool.recreate`

def overflow(self) -> int: (source) ¶

Undocumented

def recreate(self) -> QueuePool: (source) ¶

overrides sqlalchemy.pool.base.Pool.recreate

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.

def size(self) -> int: (source) ¶

Undocumented

def status(self) -> str: (source) ¶

overrides sqlalchemy.pool.base.Pool.status

Undocumented

def timeout(self) -> float: (source) ¶

Undocumented

def _dec_overflow(self) -> Literal[True]: (source) ¶

Undocumented

def _do_get(self) -> ConnectionPoolEntry: (source) ¶

overrides sqlalchemy.pool.base.Pool._do_get

Implementation for :meth:`get`, supplied by subclasses.