[
http://issues.apache.org/jira/browse/DERBY-1142?page=comments#action_12371579 ]
Knut Anders Hatlen commented on DERBY-1142:
-------------------------------------------
Thanks for looking into this, Anders!
The activation is removed from acts when Activation.close() is
called. Normally, EmbedResultSet.close() calls theResults.finish()
(implemented in BasicNoPutResultSetImpl), which calls
activation.close(). From BasicNoPutResultSetImpl.finishAndRTS():
if (isTopResultSet && activation.isSingleExecution())
activation.close();
For the metadata query, isSingleExecution() returns false, hence
activation.close() isn't called when the result set is closed. It
seems like isSingleExecution() is true only if a Statement is used,
but the metadata query uses a PreparedStatement.
As you noticed, the PreparedStatement is not being closed. However, I
found this in EmbedResultSet.close():
if (forMetaData) {
LanguageConnectionContext lcc =
getEmbedConnection().getLanguageConnection();
if (lcc.getActivationCount() > 1) {
// we do not want to commit here as there seems to be other
// statements/resultSets currently opened for this connection.
} else if (owningStmt != null) {
// allow the satement to commit if required.
owningStmt.resultSetClosing(this);
}
} else if (owningStmt != null) {
// allow the satement to commit if required.
owningStmt.resultSetClosing(this);
}
Could we solve the problem by invoking owningStmt.close() when
forMetaData is true and the activation count is not greater than one?
> Metadata calls leak memory
> --------------------------
>
> Key: DERBY-1142
> URL: http://issues.apache.org/jira/browse/DERBY-1142
> Project: Derby
> Type: Bug
> Components: JDBC
> Versions: 10.1.2.1, 10.2.0.0
> Reporter: Knut Anders Hatlen
> Priority: Minor
> Attachments: metadataloop.java
>
> When calling a DatabaseMetaData method that returns a ResultSet,
> memory is leaked. A loop like this (using the embedded driver)
> while (true) {
> ResultSet rs = dmd.getSchemas();
> rs.close();
> }
> will eventually cause an OutOfMemoryError.
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