Question

I’m running into the following (common) error after I added a new DB table, hibernate class, and other classes to access the hibernate class:

java.lang.OutOfMemoryError: Java heap space

Here’s the relevant code:

From .jsp:

<% 
com.companyconnector.model.HomepageBean homepage = new com.companyconnector.model.HomepageBean();
%>

From HomepageBean:

public class HomepageBean {

        ...

    private ReviewBean review1;
    private ReviewBean review2;
    private ReviewBean review3;



    public HomepageBean () {

        ...

        GetSurveyResults gsr = new GetSurveyResults();
        List<ReviewBean> rbs = gsr.getRecentReviews();  
        review1 = rbs.get(0);  
        review2 = rbs.get(1);
        review3 = rbs.get(2);
}

From GetSurveyResults:

public List<ReviewBean> getRecentReviews() {

    List<OpenResponse> ors = DatabaseBean.getRecentReviews();
    List<ReviewBean> rbs = new ArrayList<ReviewBean>();


    for(int x = 0; ors.size() > x; x =+ 2) {

     String employer = "";
     rbs.add(new ReviewBean(ors.get(x).getUid(), employer, ors.get(x).getResponse(), ors.get(x+1).getResponse()));

    }

    return rbs;

}

and lastly, from DatabaseBean:

public static List<OpenResponse> getRecentReviews() {

  SessionFactory session = HibernateUtil.getSessionFactory();
  Session sess = session.openSession();
  Transaction tx = sess.beginTransaction();

  List results = sess.createQuery( 
    "from OpenResponse where (uid = 46) or (uid = 50) or (uid = 51)"
  ).list();

  tx.commit();
  sess.flush();
  sess.close();
  return results;

}

Sorry for all the code and such a long message, but I’m getting over a million instances of ReviewBean (I used jProfiler to find this). Am I doing something wrong in the for loop in GetSurveyResults? Any other problems?

I’m happy to provide more code if necessary.

Thanks for the help.

Joe

Answer 1

Using JProfiler to find which objects occupy the memory is a good first step. Now that you know that needlessly many instances are created, a logical next analysis step is to run your application in debug mode, and step through the code that allocates the ReviewBeans. If you do that, the bug should be obvious. (I am pretty sure I spotted it, but I’d rather teach you how to find such bugs on your own. It’s a skill that is indispensable for any good programmer).