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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