Hello, all:

 

While our application is shutting down, it is possible that some of its components may continue execution or even begin execution of the queries on the in-memory Derby DB. In such situation, Derby starts throwing all kinds of exceptions, including a Null Pointer Exception (pls see excerpt from our log below). Is it possible to have Derby shut down more gracefully, so that the application doesn’t pester our error log files with these exceptions?

 

Of course, I may be able to work around by implementing an atomic reference counter, which gets incremented before a query is executed and decremented when it’s done. And then, upon a request to shut down Derby, wait until that counter gets to 0 before sending the shutdown URL. But it seems kludgy to me and I would wish for a more elegant way for Derby itself to handle this, as it has the intimate knowledge of what’s being executed and what’s not.

 

Or, perhaps, you could recommend a better approach?

 

Thank you.

Pavel.

 

2012-01-12 16:15:23,224 [main] INFO  Executing Derby Shutdown Command: jdbc:derby:memory:geni;drop=true

2012-01-12 16:15:23,230 SQL Exception due to executing statement

java.sql.SQLException: Java exception: ': java.lang.NullPointerException'.

        at org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException(Unknown Source)

        at org.apache.derby.impl.jdbc.Util.newEmbedSQLException(Unknown Source)

        at org.apache.derby.impl.jdbc.Util.javaException(Unknown Source)

        at org.apache.derby.impl.jdbc.TransactionResourceImpl.wrapInSQLException(Unknown Source)

        at org.apache.derby.impl.jdbc.TransactionResourceImpl.handleException(Unknown Source)

        at org.apache.derby.impl.jdbc.EmbedConnection.handleException(Unknown Source)

        at org.apache.derby.impl.jdbc.ConnectionChild.handleException(Unknown Source)

        at org.apache.derby.impl.jdbc.EmbedStatement.executeStatement(Unknown Source)

        at org.apache.derby.impl.jdbc.EmbedPreparedStatement.executeStatement(Unknown Source)

        at org.apache.derby.impl.jdbc.EmbedPreparedStatement.executeQuery(Unknown Source)

        ...

Caused by: java.sql.SQLException: Java exception: ': java.lang.NullPointerException'.

        at org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source)

        at org.apache.derby.impl.jdbc.SQLExceptionFactory40.wrapArgsForTransportAcrossDRDA(Unknown Source)

        ... 13 more

Caused by: java.lang.NullPointerException

        at java.util.LinkedList.remove(LinkedList.java:225)

        at org.apache.derby.impl.services.locks.LockControl.removeWaiter(Unknown Source)

        at org.apache.derby.impl.services.locks.LockControl.getNextWaiter(Unknown Source)

        at org.apache.derby.impl.services.locks.ConcurrentLockSet.lockObject(Unknown Source)

        at org.apache.derby.impl.services.locks.ConcurrentLockSet.zeroDurationLockObject(Unknown Source)

        at org.apache.derby.impl.services.locks.AbstractPool.zeroDurationlockObject(Unknown Source)

        at org.apache.derby.impl.services.locks.ConcurrentPool.zeroDurationlockObject(Unknown Source)

        at org.apache.derby.impl.store.raw.xact.RowLocking2nohold.lockRecordForRead(Unknown Source)

        at org.apache.derby.impl.store.access.conglomerate.OpenConglomerate.lockPositionForRead(Unknown Source)

        at org.apache.derby.impl.store.access.conglomerate.GenericScanController.fetchRows(Unknown Source)

        at org.apache.derby.impl.store.access.conglomerate.GenericScanController.fetchSet(Unknown Source)

        at org.apache.derby.impl.store.access.BackingStoreHashTableFromScan.<init>(Unknown Source)

        at org.apache.derby.impl.store.access.RAMTransaction.createBackingStoreHashtableFromScan(Unknown Source)

        at org.apache.derby.impl.sql.execute.HashScanResultSet.openCore(Unknown Source)

        at org.apache.derby.impl.sql.execute.JoinResultSet.openRight(Unknown Source)

        at org.apache.derby.impl.sql.execute.JoinResultSet.openCore(Unknown Source)

        at org.apache.derby.impl.sql.execute.ProjectRestrictResultSet.openCore(Unknown Source)

        at org.apache.derby.impl.sql.execute.ProjectRestrictResultSet.openCore(Unknown Source)

        at org.apache.derby.impl.sql.execute.GroupedAggregateResultSet.openCore(Unknown Source)

        at org.apache.derby.impl.sql.execute.ProjectRestrictResultSet.openCore(Unknown Source)

        at org.apache.derby.impl.sql.execute.ScrollInsensitiveResultSet.openCore(Unknown Source)

        at org.apache.derby.impl.sql.execute.BasicNoPutResultSetImpl.open(Unknown Source)

        at org.apache.derby.impl.sql.GenericPreparedStatement.executeStmt(Unknown Source)

        at org.apache.derby.impl.sql.GenericPreparedStatement.execute(Unknown Source)

        ... 6 more

2012-01-12 16:15:23,231 SQL Exception due to executing statement

java.sql.SQLNonTransientConnectionException: Database 'memory:geni' shutdown.

        at org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException(Unknown Source)

        at org.apache.derby.impl.jdbc.Util.generateCsSQLException(Unknown Source)

        at org.apache.derby.impl.jdbc.TransactionResourceImpl.wrapInSQLException(Unknown Source)

        at org.apache.derby.impl.jdbc.TransactionResourceImpl.handleException(Unknown Source)

        at org.apache.derby.impl.jdbc.EmbedConnection.handleException(Unknown Source)

        at org.apache.derby.impl.jdbc.ConnectionChild.handleException(Unknown Source)

        at org.apache.derby.impl.jdbc.EmbedStatement.executeStatement(Unknown Source)

        at org.apache.derby.impl.jdbc.EmbedPreparedStatement.executeStatement(Unknown Source)

        at org.apache.derby.impl.jdbc.EmbedPreparedStatement.executeQuery(Unknown Source)

        ...

Caused by: java.sql.SQLException: Database 'memory:geni' shutdown.

        at org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown Source)

        at org.apache.derby.impl.jdbc.SQLExceptionFactory40.wrapArgsForTransportAcrossDRDA(Unknown Source)

        ... 12 more

Caused by: ERROR 08006: Database 'memory:geni' shutdown.

        at org.apache.derby.iapi.error.StandardException.newException(Unknown Source)

        at org.apache.derby.impl.jdbc.TransactionResourceImpl.shutdownDatabaseException(Unknown Source)

        ... 9 more

 

 

 

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