Data Source Connection pool properties

You can configure connection pool related properties from the Connection pool screen.

  • Connection Timeout: Specify the interval, in seconds, after which a connection request times out and a ConnectionWaitTimeoutException is thrown. This can occur when the pool is at its maximum (Max Connections) and all of the connections are in use by other applications for the duration of the wait. For example, if Connection Timeout is set to 300 and the maximum number of connections is reached, the Pool Manager waits for 300 seconds for an available physical connection. If a physical connection is not available within this time, the Pool Manager throws a ConnectionWaitTimeoutException.

  • Max Connections: Specify the maximum number of physical connections that can be created in this pool. These are the physical connections to the back-end database. Once this number is reached, no new physical connections are created and the requester waits until a physical connection that is currently in use is returned to the pool, or a ConnectionWaitTimeoutException is thrown. For example, if Max Connections is set to 5, and there are five physical connections in use, the Pool Manager waits for the amount of time specified in Connection Timeout for a physical connection to become free. If, after that time, there are still no free connections, the Pool Manager throws a ConnectionWaitTimeoutException to the application.

  • Min Connections: Specify the minimum number of physical connections to be maintained. Until this number is reached, the pool maintenance thread does not discard any physical connections. However, no attempt is made to bring the number of
    connections up to this number. For example, if Min Connections is set to 3, and one physical connection is created, that connection is not discarded by the Unused Timeout thread. By the same token, the thread does not automatically create two additional physical connections to reach the Min Connections setting.

  • Reap Time: Specify the interval, in seconds, between runs of the pool maintenance
    thread. For example, if Reap Time is set to 60, the pool maintenance thread runs every 60 seconds. The Reap Time interval affects the accuracy of the Unused Timeout and Aged Timeout settings. The smaller the interval you set, the greater the accuracy. When the pool maintenance thread runs, it discards any connections that have been unused for longer than the time value specified in Unused Timeout, until it reaches the number of connections specified in Min Connections. The pool maintenance thread also discards any connections that remain active longer than the time value specified in Aged Timeout.

  • Unused Timeout: Specify the interval in seconds after which an unused or idle connection is discarded. For example, if the unused timeout value is set to 120, and the pool maintenance thread is enabled (Reap Time is not 0), any physical connection that remains unused for two minutes is discarded. Note that accuracy of this timeout, as well as performance, is affected by the Reap Time value. See the Reap Time bullet for more information.

  • Aged Timeout: Specify the interval in seconds before a physical connection is discarded, regardless of recent usage activity. Setting Aged Timeout to 0 allows active physical connections to remain in the pool indefinitely. For example, if the Aged Timeout value is set to 1200, and the Reap Time value is not 0, any physical connection that remains in existence for 1200 seconds (20 minutes) is discarded from the pool. Note that accuracy of this timeout, as well as performance, is affected by the Reap Time value. See Reap Time for more information.

  • Purge Policy: Specify how to purge connections when a stale connection or fatal connection error is detected. Valid values are EntirePool and FailingConnectionOnly. If you choose EntirePool, all physical connections in the pool are destroyed when a stale connection is detected. If you choose FailingConnectionOnly, the pool attempts to destroy only the stale connection. The other connections remain in the pool. Final destruction of connections that are in use at the time of the error might be delayed. However, those connections are never returned to the pool.


Madhava Kulkarni said...

hi Sunil,

i am facing performance issue with my WAS6 and dB queries are hanging and taking more time.

Any thoughts will it be due to the connection pooling or number of connnections in the pool or any thing else in WAS firstly so that i can deal with DB with DBA experts.


sudhakar jahn said...

Hi Sunil....Your notes is more valuable and helpful to people who are looking at websphere side. Thanks for providing notes for all the topics..But i seen no document for troubleshooting issue.

Avery very thanks to you for providing data to learn subject.

Anonymous said...

This is copied from an IBM site, would you please provide your own input..