[
http://issues.apache.org/jira/browse/DERBY-210?page=comments#action_12315888 ]
Kathey Marsden commented on DERBY-210:
--------------------------------------
The workaround for this issue is for the application to explicitly close all
prepared statements. The close is often omitted for error conditions causing
slow leaks. Applications can't rely on garbage collection to clean up prepared
statements.
A good way to diagnose which statements are leaking if you have this
problem is to run
java org.apache.derby.drda.NetworkServerControl runtimeinfo
runtimeinfo shows the statements currently open on the server.
> Network Server will leak prepared statements if not explicitly closed by the
> user until the connection is closed
> ----------------------------------------------------------------------------------------------------------------
>
> Key: DERBY-210
> URL: http://issues.apache.org/jira/browse/DERBY-210
> Project: Derby
> Type: Bug
> Components: Network Client
> Reporter: Kathey Marsden
> Attachments: derbyStress.java
>
> 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.
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