The virtualizer doesn't seem to be used

JRFileVirtualizer virtualizer = new JRFileVirtualizer( 2, Configuration.getParameter("report.virtualizer.physical.temp.path"«») );<br />
			parameters.put( JRParameter.REPORT_VIRTUALIZER, virtualizer );<br />
            <br />
			DataSource dataSource = new DataSource( parameters, jasperReport.getQuery().getText(), connection );<br />
			<br />
            JasperPrint jasperPrint = JasperFillManager.fillReport( jasperReport, parameters, dataSource );<br />
            //-----------------------------------------------------<br />
            <br />
            JRXlsExporter exporterXLS = new JRXlsExporter();<br />
            exporterXLS.setParameter( JRXlsExporterParameter.JASPER_PRINT, jasperPrint );<br />
            //exporterXLS.setParameter( JRXlsExporterParameter.OUTPUT_STREAM, output );<br />
            exporterXLS.setParameter( JRXlsExporterParameter.OUTPUT_FILE_NAME, PDFReportCreator.BASE_PATH_FOR_PDF + report.getPdfFilePath() );<br />
            exporterXLS.setParameter( JRXlsExporterParameter.IS_ONE_PAGE_PER_SHEET, Boolean.TRUE );<br />
            exporterXLS.setParameter( JRXlsExporterParameter.IS_AUTO_DETECT_CELL_TYPE, Boolean.FALSE );<br />
            exporterXLS.setParameter( JRXlsExporterParameter.IS_WHITE_PAGE_BACKGROUND, Boolean.FALSE );<br />
            exporterXLS.setParameter( JRXlsExporterParameter.IS_REMOVE_EMPTY_SPACE_BETWEEN_ROWS, Boolean.TRUE );<br />
            exporterXLS.exportReport();</td></tr></tbody></table><br />
<br />
The exportReport method never ends...<br />
<br />
<table align="center" border="0" cellpadding="3" cellspacing="1" width="90%"><tbody><tr><td><b>Code:</b></td></tr><tr><td><pre>/**<br />
 * <br />
 */<br />
package com.dotbase.jasper.model;<br />
<br />
import java.sql.Connection;<br />
import java.sql.PreparedStatement;<br />
import java.sql.ResultSet;<br />
import java.sql.SQLException;<br />
import java.util.Map;<br />
import java.util.Set;<br />
<br />
import net.sf.jasperreports.engine.JRDataSource;<br />
import net.sf.jasperreports.engine.JRException;<br />
import net.sf.jasperreports.engine.JRField;<br />
<br />
/**<br />
 * @author lrobert<br />
 * Dataset pour la virtualisation (traîtement de gros rapports)<br />
 */<br />
public class DataSource implements JRDataSource<br />
{<br />
	private static final int MAX_RESULT_PER_PAGE = 1000;<br />
	<br />
	private String query;<br />
	private Connection connection;<br />
	private ResultSet rsReportData;<br />
	private int currentPage = 0;<br />
	<br />
	public DataSource( Map<String, Object> parameters, String query, Connection connection ) throws SQLException<br />
	{<br />
		//exécuter la requête<br />
		connection.setAutoCommit( false );<br />
		PreparedStatement statement = connection.prepareStatement( query );<br />
		statement.setFetchSize( 100 );<br />
		this.rsReportData = Database.executeSelect( statement );<br />
	}<br />
	<br />
	public Object getFieldValue( JRField jrField ) throws JRException<br />
	{<br />
		try<br />
		{<br />
			Object field = rsReportData.getObject( jrField.getName() );<br />
			return field;<br />
		}<br />
		catch( SQLException e )<br />
		{<br />
			throw new JRException( e );<br />
		}<br />
	}<br />
<br />
	private int iNext = 0;<br />
	public boolean next() throws JRException<br />
	{<br />
		try<br />
		{<br />
			return rsReportData.next();<br />
		}<br />
		catch( SQLException e )<br />
		{<br />
			throw new JRException( e );<br />
		}<br />
	}<br />
<br />
}<br />
</td></tr></tbody></table><br />
<br />
Could somebody  help me to solve that ?<br />
<br />
How could I be sure my virtualizer is used ?<br />
<br />
What does the first parameter of the virtualizer ("maxsize") mean ?<br />
<br />
Thank you for your help