JdbcCursorItemReader#useSharedExtendedConnection does not attach the connection to the transaction [BATCH-2674]

Eduardo Macarron opened BATCH-2674 and commented

According to the javadoc, when useSharedExtendedConnection is set, JdbcCursorItemReader should pick a connection from the transaction and keep it open by filtering futther calls to close() (by the use of the ExtendedConnectionDataSourceProxy. Javadoc:

"Indicate whether the connection used for the cursor should be used by all other processing thus sharing the same transaction"

However seems it is not doing so.

It implements ItemStream and ItemReader. Seems that spring batch is calling ItemStream#open when transaction is not yet active. And connection opening is happening there. This line in AbstractCursorItemReader#initializeConnection()

this.con = DataSourceUtils.getConnection(dataSource);

Ends up creating a new connection not bound to a transaction.

...
(previous transaction ending...)

[DEBUG] org.springframework.jdbc.datasource.DataSourceTransactionManager.doCleanupAfterCompletion(DataSourceTransactionManager.java:368) - Releasing JDBC Connection [org.hsqldb.jdbc.JDBCConnection@4f8caaf3] after transaction
[DEBUG] org.springframework.jdbc.datasource.DataSourceUtils.doReleaseConnection(DataSourceUtils.java:329) - Returning JDBC Connection to DataSource

(ItemStream#open() called)

[DEBUG] org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:110) - Fetching JDBC Connection from DataSource
[DEBUG] org.springframework.jdbc.datasource.SimpleDriverDataSource.getConnectionFromDriver(SimpleDriverDataSource.java:138) - Creating new JDBC Driver Connection to [jdbc:hsqldb:mem:dataSource]
...

Following the execution until the close method gets called confirms it. Synchronization is not active and there is not any connection holder in the thread.

This is quite an old property so it is hard to belive that it is not working as expected so it is more likely that I am missing something important. Sorry if so! and thanks for having a look into this.

No further details from BATCH-2674

Start by tracing ItemStream#open into AbstractCursorItemReader#initializeConnection(), especially the DataSourceUtils.getConnection(dataSource) call, and compare it with useSharedExtendedConnection and ExtendedConnectionDataSourceProxy. Reproduce the transaction and connection logs described in the issue; done means the cursor connection is obtained from and remains shared with the transaction as the javadoc specifies.