Class FixedSizePool (3.51.0) 

FixedSizePool(
    size=10, default_timeout=10, labels=None, database_role=None, max_age_minutes=55
)

Concrete session pool implementation:

  • Pre-allocates / creates a fixed number of sessions.

  • "Pings" existing sessions via session.exists before returning sessions that have not been used for more than 55 minutes and replaces expired sessions.

  • Blocks, with a timeout, when get is called on an empty pool. Raises after timing out.

  • Raises when put is called on a full pool. That error is never expected in normal practice, as users should be calling get followed by put whenever in need of a session.

Parameters
Name Description
size int

fixed pool size
default_timeout int

default timeout, in seconds, to wait for a returned session.
labels dict (str -> str) or None

(Optional) user-assigned labels for sessions created by the pool.
database_role str

(Optional) user-assigned database_role for the session.

Methods

bind

bind(database)

Associate the pool with a database.

Parameter
Name Description
database Database

database used by the pool to used to create sessions when needed.

clear

clear()

Delete all sessions in the pool.

get

get(timeout=None)

Check a session out from the pool.

Parameter
Name Description
timeout int

seconds to block waiting for an available session
Exceptions
Type Description
`queue.Empty if the queue is empty.
Returns
Type Description
Session an existing session from the pool, or a newly-created session.

put

put(session)

Return a session to the pool.

Never blocks: if the pool is full, raises.

Parameter
Name Description
session Session

the session being returned.
Exceptions
Type Description
`queue.Full if the queue is full.