Name: krC82822 Date: 07/31/2001


java version "1.3.1"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.1-b24)
Java HotSpot(TM) Client VM (build 1.3.1-b24, mixed mode)

While profiling my application (using JProbe 3.0), I noticed that Int[] array
objects were being leaked. I tracked this down to an allocation occurring in
JdbcOdbcResultSet.setRowStatusPtr() - JdbcOdbcResultSet.java:4356

The leak only occurs when calling createStatement() using non-default values
for the ResultSet type (i.e. anything other than ResultSet.TYPE_FORWARD_ONLY
and ResultSet.CONCUR_READ_ONLY).

Each call to executeQuery() generates a new resultSet that leaks 1 Int[] object
of 4 bytes. For an application making many, many queries the implications of
this are horrific! One day's worth of leaks in my Application equate to
0.5MBytes of memory when running at 1/100 of its expected capacity.

I have experimated with the code listed below. Regardless of whether I re-use
the Statement, or don't call 'close()' on the ResultSet the leak still occurs.

Non-default ResultSet's because of MSSQLServer's BAD ODBC support for multiple
active ResultSet's.

Extract and tailor the following code to query any DB table using the bridge to
reproduce the bug, not forgetting to use a profiler to see the leak.


-------------------------Start of ResultSetBug.java
import java.sql.*;
public class ResultSetBug
{
public ResultSetBug()
{
DemonstrateTheBug();
}
static public void main(String[] args)
{
new ResultSetBug();
}
private void DemonstrateTheBug()
{
try
{
String dbDriver = "sun.jdbc.odbc.JdbcOdbcDriver";
String dbUrl = "jdbc:odbc:<DSN>";
String dbUser = "<User>";
String dbPassword = "<Password>";

Class.forName(dbDriver);
Connection con = DriverManager.getConnection( dbUrl,

dbUser,

dbPassword);
while(true)
{
for (int queryCount = 0; queryCount < 1000;
queryCount++)
{
System.out.print("*");
Statement s = con.createStatement(
ResultSet.TYPE_SCROLL_INSENSITIVE,

ResultSet.CONCUR_READ_ONLY );

ResultSet rs = s.executeQuery( "select
* from MyTable" );

rs.close();
s.close();
rs = null;
s = null;
}

Thread.sleep( 60000 );
}
}
catch(java.lang.ClassNotFoundException cnfe)
{
System.out.println("Can't locate driver : " +
cnfe.toString() );
}
catch(InterruptedException ie)
{
System.out.println("Interrupted : " + ie.toString() );
}
catch(SQLException se)
{
System.out.println("SQLException : " + se.toString() );
}
}
}
---------------------------------------End of ResultSetBug.java
(Review ID: 129150)
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