MySQL / Hibernate Too Many Connections Error - sql

Question

Put together a very simple database using Hibernate, but notice that quite often I get the Glassdoor server error telling me "Too Many Connections".
I assume this is because I'm not correctly closing my connections when I update/add/remove database items.
Here's an example of what I do in my updateEntry.jsp-- any blantant issues? If not I can post my removeEntry.jsp and newEntry.jsp:
<%#page import="java.util.Date" %>
<%#page import="org.hibernate.Session" %>
<%#page import="org.hibernate.SessionFactory" %>
<%#page import="org.hibernate.Transaction" %>
<%#page import="org.hibernate.cfg.Configuration" %>
<%#page import="java.util.Date" %>
<%
String nId = request.getParameter("pID");
String naddress = request.getParameter("pAddress");
String nstatus = request.getParameter("pStatus");
String nassigned = request.getParameter("pAssigned");
String nnote = request.getParameter("pNote");
if (!naddress.equals("undefined"))
{
// This step will read hibernate.cfg.xml and prepare hibernate for use
org.hibernate.SessionFactory sessionFactory1 = new org.hibernate.cfg.Configuration().configure().buildSessionFactory();
org.hibernate.Session session1 = sessionFactory1.openSession();
org.hibernate.Query query1 = session1.createQuery("update Leads set Address = :naddr where Id = :nid");
query1.setParameter("nid", nId);
query1.setParameter("naddr", naddress);
query1.executeUpdate();
//out.println("Update successfully with: " + naddress);
// Actual contact insertion will happen at this step
session1.flush();
session1.close();
}
if (!nstatus.equals("undefined"))
{
// This step will read hibernate.cfg.xml and prepare hibernate for use
org.hibernate.SessionFactory sessionFactory2 = new org.hibernate.cfg.Configuration().configure().buildSessionFactory();
org.hibernate.Session session2 = sessionFactory2.openSession();
org.hibernate.Query query2 = session2.createQuery("update Leads set Status = :nstatus where Id = :nid");
query2.setParameter("nid", nId);
query2.setParameter("nstatus", nstatus);
query2.executeUpdate();
//out.println("Update successfully with: " + nstatus);
// Actual contact insertion will happen at this step
session2.flush();
session2.close();
}
if (!nassigned.equals("undefined"))
{
// This step will read hibernate.cfg.xml and prepare hibernate for use
org.hibernate.SessionFactory sessionFactory3 = new org.hibernate.cfg.Configuration().configure().buildSessionFactory();
org.hibernate.Session session3 = sessionFactory3.openSession();
org.hibernate.Query query3 = session3.createQuery("update Leads set Assigned = :nassigned where Id = :nid");
query3.setParameter("nid", nId);
query3.setParameter("nassigned", nassigned);
query3.executeUpdate();
//out.println("Update successfully with: " + nassigned);
// Actual contact insertion will happen at this step
session3.flush();
session3.close();
}
if (!nnote.equals("undefined"))
{
// This step will read hibernate.cfg.xml and prepare hibernate for use
org.hibernate.SessionFactory sessionFactory4 = new org.hibernate.cfg.Configuration().configure().buildSessionFactory();
org.hibernate.Session session4 = sessionFactory4.openSession();
org.hibernate.Query query4 = session4.createQuery("update Leads set Notes = :nnote where Id = :nid");
query4.setParameter("nid", nId);
query4.setParameter("nnote", nnote);
query4.executeUpdate();
//out.println("Update successfully with: " + nnote);
// Actual contact insertion will happen at this step
session4.flush();
session4.close();
}
%>

Answer 1

You should not initialize hibernate within the JSP, you just initialize once when the context start.
Normally you would put the hibernate factory initialization upon context initialization, then you should get the session from the factory once at the start of every request.
#WebListener
public class HibernateListener implements ServletContextListener {
public static final String ENTITY_MANAGER = "entity.manager";
public void contextInitialized(ServletContextEvent evt) {
SessionFactory sessionFactory = new Configuration()
.configure().buildSessionFactory();
evt.getServletContext()
.setAttribute(ENTITY_MANAGER, sessionFactory);
}
public void contextDestroyed(ServletContextEvent evt) {
SessionFactory sessionFactory = (SessionFactory) evt.getServletContext()
.getAttribute(ENTITY_MANAGER);
sessionFactory.close();
}
}
Then you could get the session picking the entityManager from the servletContext.
<% SessionFactory factory =(SessionFactory) session.getServletContext()
.getAttribute(HibernateListener.ENTITY_MANAGER); %>
I think you should carefully read Hibernate Quickstart Guide