Various databases accessed at the same time JPA

Question

Today I have the following scenario: my customers enter my site and appears the login screen, where I ask the User Group, Login and Password.

For the Group I have a database, where it has the data of the user’s database ie, on which server it is allocated the name etc.

With that, I check if the group exists. If it exists I close the connection of my Group database, which is called Manager, and open the connection of the user’s database.

Each user has their database, so I open the connection of the user’s database after checking if there is a group and write to one HTTPSESSION (Obs : I record the EntityManegerFactory in session), so every time he goes to do a search, I do the EntityManager receive this Factory session.

I wonder if this can slow down the system, because my java server is crashing, I wonder if this is the reason why.

Here I write the customer database in the session:

 public EntityManager getEntityManager(String PU, String Local, String endfdb) {

    if (PU.equals("0")) {
        GestorEMF = Persistence.createEntityManagerFactory("GestorPU");
        return GestorEMF.createEntityManager();
    } else {
        Properties props = new Properties();

        props.setProperty("hibernate.connection.url", "jdbc:firebirdsql:"+endfdb+"/3050:" + Local);

        usrEMF = Persistence.createEntityManagerFactory(PU, props);
        HttpSession sess = (HttpSession) FacesContext.getCurrentInstance().getExternalContext().getSession(false);
        sess.setAttribute("mitryusEMF", mitryusEMF);
        return mitryusEMF.createEntityManager();
    }
}

Here I give the EM every time the user needs:

 public EntityManager getEntityMitryus() {
    EntityManagerFactory usuario = (EntityManagerFactory) getSession().getAttribute("mitryusEMF");

    return usuario.createEntityManager();
}