Memory leak when transferring pdf...help needed

Question

Dear All,
I'm a newbie in developing java app. I'm making a web based application in reporting using JSP. java 1.6.02, jasper report 204, i-report 2.0.0
Client : OS : Win xp, memory 512MB
Server : Tomcat 6.0
DB Server : SQL Server 2005
OS Server : Windows Server 2003, memory 1GB
Report spec : .pdf based, with up to 1million record
Here's the code :
String query;
        try {
        String filereport = request.getRealPath("division/accounting/template/POReport.jrxml");
        InputStream input = new FileInputStream(filereport);
        Class.forName(odbcDriver);
        Connection conn = DriverManager.getConnection(odbcURL,username,passwd);
        ResultSet rset = null;
        CallableStatement cs = null;
        query = "{ call sp_tpo_list }";
          cs = conn.prepareCall(query);
          rset = cs.executeQuery();
        JRDataSource dataSource = new JRResultSetDataSource(rset);
        JasperDesign design = JRXmlLoader.load(input);
        JasperReport report = JasperCompileManager.compileReport(design);
        JasperPrint print = JasperFillManager.fillReport(report, null, dataSource);
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        JasperExportManager.exportReportToPdfStream(print, baos);
        response.setContentType("application/pdf");
        response.setContentLength(baos.size());
        ServletOutputStream sos;
        sos = response.getOutputStream();
        baos.writeTo(sos);
        sos.flush();
        rset.close();
        cs.close();
        conn.close();
        sos.close();
        baos.close();
        input.close();      
        catch (FileNotFoundException fe) {}
        catch (JRException jre) {}
        catch (ClassNotFoundException cnfe) {}
        catch (SQLException sqle) {} 
        catch (IOException ioe) {}I've already increase heap memory in Tomcat Manager -Xms 64Mb -Xmx 512Mb.
But when i test with 1million record, out of heap memory error is coming out.
When i test with 500.000 record, it work out, but only when 1 client access. More than 1 client, out of heap memory error generated by the system.
How can this happen? How can i detect memory leaks occured in the program?
And pls let me know if you see something is missing in the code above.
Thank you

Answer 1

I dont think you have a memory leak. I think the problem is the xml file is 1000000 records long and takes up too much memory. Even if you find a way to increase memory size, you are loading down the server too much for other people's applications to run. I suggest instead reading up on xml and learning how to read in only a few records at a time, processing it, and getting the next set of records to process. There are two methods to parse an xml file using an xml parser, one is to parse it all and put it in memory, the other is to process one record at a time (an xml book explains it better).
However, I question why you have reports that are 1000000 records long. end-users cannot effectively use such records (you cant scroll through 1000000 records). I suggest finding a way to greatly decrease the number of records in each file such as by providing just the records a particular user needs to do his job and not all records. For instance, put a textfield on his screen to let him only fetch records within a certain date range.
Lastly, I suggest putting your code in a try/catch/finally block where the finally block actually closes the objects. Example:
finally{
if(conn!=null)
conn.close();
}