On 6/29/20 12:17 PM, Robert Paschek wrote:
Hello, DBCP has a feature to pool PreparedStatements for the lifetime of a connection. This results in cursors being open and locks in the database for a long time, which could cause problems with administrative tasks in the database. That why I would prefer this pool to be more short-living, that means that the pool is filled while the application is using the connection und cleared when the application is returning the connection to the ConnectionPool. This way the application can still benefit from the Statement-cache in mass operations, without creating headaches for database admins. I would suggest an additional setting like limitPreparedStatementPoolToConnectionUse or something similar. What do you think? Regards, Robert
One way to workaround the need to periodically clean up would be to either set maximum lifetimes on connections or periodically invalidate them. That would force the underlying PoolingConnections to be closed, which would in turn cause the statement pools to be closed.
The feature request sounds reasonable to me. For anyone interested in creating a patch to implement this, here is a way that might work to implement it:
Connections that pool statements are PoolingConnections. Add a property to this class to determine whether or not to clear the statement pool when a connection is returned to the pool. Override DelegatingConnnection's passivate method to first call super() but then examine the property and if so configured, clear (not close) the statement pool. Modify PoolableConnectionFactory to set the property and BasicDataSource to pass it in.
Probably best to open a JIRA for this. I don't have time to work on it now, but I would be willing to review PRs.
Phil
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