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    <p>The problem was happening because of small value <code>time_out</code> var on mysql server.</p> <p>In my situation time_out was set to 1 minute. Using C3PO pooling mechanism we can optimize JDBC.</p> <p>Download <strong>c3p0</strong> -> <a href="http://sourceforge.net/projects/c3p0/" rel="nofollow noreferrer">http://sourceforge.net/projects/c3p0/</a></p> <p>I'm using <strong>hibernate 3.0</strong>.</p> <p><strong>hibernate.cfg.xml</strong></p> <pre><code>&lt;?xml version='1.0' encoding='UTF-8'?&gt; &lt;!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"&gt; &lt;hibernate-configuration&gt; &lt;session-factory&gt; &lt;property name="connection.driver_class"&gt;com.mysql.jdbc.Driver&lt;/property&gt; &lt;property name="connection.url"&gt;jdbc:mysql://databasehost:3306/databasename&lt;/property&gt; &lt;property name="connection.username"&gt;user&lt;/property&gt; &lt;property name="connection.password"&gt;psw&lt;/property&gt; &lt;property name="dialect"&gt;org.hibernate.dialect.MySQLDialect&lt;/property&gt; &lt;property name="hibernate.hbm2ddl.auto"&gt;update&lt;/property&gt; &lt;property name="show_sql"&gt;false&lt;/property&gt; &lt;!-- hibernate c3p0 settings --&gt; &lt;property name="connection.provider_class"&gt;org.hibernate.connection.C3P0ConnectionProvider&lt;/property&gt; &lt;property name="hibernate.c3p0.acquire_increment"&gt;3&lt;/property&gt; &lt;property name="hibernate.c3p0.idle_test_period"&gt;10&lt;/property&gt; &lt;property name="hibernate.c3p0.min_size"&gt;5&lt;/property&gt; &lt;property name="hibernate.c3p0.max_size"&gt;75&lt;/property&gt; &lt;property name="hibernate.c3p0.max_statements"&gt;10&lt;/property&gt; &lt;property name="hibernate.c3p0.timeout"&gt;50&lt;/property&gt; &lt;property name="hibernate.c3p0.preferredTestQuery"&gt;select 1&lt;/property&gt; &lt;property name="hibernate.c3p0.testConnectionOnCheckout"&gt;true&lt;/property&gt; &lt;!-- Mapping files --&gt; &lt;mapping class="xxx.xxx.xxx.xxx" /&gt; &lt;mapping class="xxx.xxx.xxx.xxx" /&gt; &lt;mapping class="xxx.xxx.xxx.xxx" /&gt; &lt;mapping class="xxx.xxx.xxx.xxx" /&gt; &lt;/session-factory&gt; &lt;/hibernate-configuration&gt; </code></pre> <p><strong>PersistenceManager.java</strong></p> <pre><code>import java.io.PrintStream; import org.hibernate.SessionFactory; import org.hibernate.cfg.AnnotationConfiguration; import org.hibernate.cfg.Configuration; public class PersistenceManager { private static SessionFactory sessionFactory = null; private static PersistenceManager singleton = null; public static PersistenceManager getInstance() { if (singleton == null) { singleton = new PersistenceManager(); } return singleton; } public SessionFactory getSessionFactory() { if (sessionFactory == null) createSessionFactory(); return sessionFactory; } protected void createSessionFactory() { sessionFactory = new AnnotationConfiguration().configure() .buildSessionFactory(); } public void destroySessionFactory() { if (sessionFactory != null) { sessionFactory.close(); sessionFactory = null; } } } </code></pre> <p><strong>Example 1:</strong></p> <pre><code>import org.hibernate.HibernateException; import org.hibernate.Query; import org.hibernate.Session; public Users Login( String username, String password) { Session session = null; try { String hql = "select u from Users u where u.username like :p1 and u.password like :p2"; session = PersistenceManager.getInstance().getSessionFactory().openSession(); Query q = session.createQuery(hql) .setParameter("p1", username) .setParameter("p2", password); if (q.list().size() == 0) { session.close(); return new Users(); } Users user = (Users)q.list().get(0); session.close(); return user; } catch (Exception e) { session.close(); } } </code></pre> <p><strong>Example 2:</strong></p> <pre><code>import org.hibernate.HibernateException; import org.hibernate.Query; import org.hibernate.Session; public String Registration(Users u) { Session session = null; try { String hql = "select u from Users u where u.username like :p1"; session = PersistenceManager.getInstance().getSessionFactory().openSession(); Query q = session.createQuery(hql).setParameter("p1", u.getUsername()); if (q.list().size() == 0) { session.beginTransaction(); session.persist(u); session.getTransaction().commit(); session.close(); return new Boolean(true).toString(); } session.close(); return new Boolean(false).toString(); } catch (Exception e) { return e.toString(); } } </code></pre>
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    1. COWould you mind posting your my.cnf please? I had these timeout issues ages ago and was able to fix it by playing with my.cnf. My hosting company upgraded my server and did keep my MySQL configuration and now I have the erros back and can't remember exactly what I did
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