Class Pool

asyncpg/pool.py:329–1040

A connection pool. Connection pool can be used to manage a set of connections to the database. Connections are first acquired from the pool, then used, and then released back to the pool. Once a connection is released, it's reset to close all open cursors and other resources *excep

class Pool:
    """A connection pool.

    Connection pool can be used to manage a set of connections to the database.
    Connections are first acquired from the pool, then used, and then released
    back to the pool.  Once a connection is released, it's reset to close all
    open cursors and other resources *except* prepared statements.

    Pools are created by calling :func:`~asyncpg.pool.create_pool`.
    """

    __slots__ = (
        '_queue', '_loop', '_minsize', '_maxsize',
        '_init', '_connect', '_reset', '_connect_args', '_connect_kwargs',
        '_holders', '_initialized', '_initializing', '_closing',
        '_closed', '_connection_class', '_record_class', '_generation',
        '_setup', '_max_queries', '_max_inactive_connection_lifetime'
    )

    def __init__(self, *connect_args,
                 min_size,
                 max_size,
                 max_queries,
                 max_inactive_connection_lifetime,
                 connect=None,
                 setup=None,
                 init=None,
                 reset=None,
                 loop,
                 connection_class,
                 record_class,
                 **connect_kwargs):

        if len(connect_args) > 1:
            warnings.warn(
                "Passing multiple positional arguments to asyncpg.Pool "
                "constructor is deprecated and will be removed in "
                "asyncpg 0.17.0.  The non-deprecated form is "
                "asyncpg.Pool(<dsn>, **kwargs)",
                DeprecationWarning, stacklevel=2)

        if loop is None:
            loop = asyncio.get_event_loop()
        self._loop = loop

        if max_size <= 0:
            raise ValueError('max_size is expected to be greater than zero')

        if min_size < 0:
            raise ValueError(
                'min_size is expected to be greater or equal to zero')

        if min_size > max_size:
            raise ValueError('min_size is greater than max_size')

        if max_queries <= 0:
            raise ValueError('max_queries is expected to be greater than zero')