Learning Hibernate: too many connections
- by stivlo
I'm trying to learn Hibernate and I wrote the simplest Person Entity and I was trying to insert 2000 of them. I know I'm using deprecated methods, I will try to figure out what are the new ones later.
First, here is the class Person:
@Entity
public class Person {
private int id;
private String name;
@Id
@GeneratedValue(strategy = GenerationType.TABLE, generator = "person")
@TableGenerator(name = "person", table = "sequences", allocationSize = 1)
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
Then I wrote a small App class that insert 2000 entities with a loop:
public class App {
private static AnnotationConfiguration config;
public static void insertPerson() {
SessionFactory factory = config.buildSessionFactory();
Session session = factory.getCurrentSession();
session.beginTransaction();
Person aPerson = new Person();
aPerson.setName("John");
session.save(aPerson);
session.getTransaction().commit();
}
public static void main(String[] args) {
config = new AnnotationConfiguration();
config.addAnnotatedClass(Person.class);
config.configure("hibernate.cfg.xml"); //is the default already
new SchemaExport(config).create(true, true); //print and execute
for (int i = 0; i < 2000; i++) {
insertPerson();
}
}
}
What I get after a while is:
Exception in thread "main" org.hibernate.exception.JDBCConnectionException: Cannot open connection
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Too many connections
Now I know that probably if I put the transaction outside the loop it would work, but mine was a test to see what happens when executing multiple transactions. And since there is only one open at each time, it should work.
I tried to add session.close() after the commit, but I got
Exception in thread "main" org.hibernate.SessionException: Session was already closed
So how to solve the problem?
