[DERBY-210] Network Server will leak prepared statements if not explicitly closed by the user until the connection is closed

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 10.0.2.0
• Component/s: Network Client
• Labels: derby_triage10_9
• Urgency: Normal
• Assignee: Unassigned
• Reporter: Katherine Marsden
• Created: 11/Apr/05 10:07
• Updated: 20/Feb/12 22:18

Description

Network server will not garbage collect prepared statements that are not explicitly closed by the user. So a loop like this will leak.

...
PreparedStatement ps;

for (int i = 0 ; i < numPs; i++)
{

ps = conn.prepareStatement(selTabSql);
rs =ps.executeQuery();

while (rs.next())

{ rs.getString(1); }

rs.close();
// I'm a sloppy java programmer
//ps.close();

}

To reproduce run the attached program
java derbyStress

Both client and server will grow until the connection is closed.

It is likely that the fix for this will have to be in the client. The client does not send protocol to close the prepared statement, but rather reuses the PKGNAMCSN on the PRPSQLSTT request once the prepared statement has been closed. This is how the server knows to close the old statement and create a new one.

Issue Links

• incorporates: DERBY-1021 Perform cleanup actions which require synchronization outside the finalizer

Sub-Tasks

• Change the client driver to allow statements to be garbage-collected once they are not referenced in an application: Closed
• Finalization of statements in client driver should handle sending of CLSQRY to close result sets on network server: Open
• Prepared statements are not garbage collected on the server until the sections are reused: Open