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POConnection drop problem with Hibernate-mysql-c3p0
 

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  1. POConnection drop problem with Hibernate-mysql-c3p0
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    <p>This is an issue which I have seen all across the web. I will bring it up again as till now I don't have a fix for the same.</p> <pre><code> I am using hibernate 3. mysql 5 and latest c3p0 jar. I am getting a broken pipe exception. Following is my hibernate.cfg file. </code></pre> <p> com.mysql.jdbc.Driver org.hibernate.dialect.MySQLDialect</p> <pre><code> &lt;property name="hibernate.show_sql"&gt;true&lt;/property&gt; &lt;property name="hibernate.use_sql_comments"&gt;true&lt;/property&gt; &lt;property name="hibernate.current_session_context_class"&gt;thread&lt;/property&gt; &lt;property name="connection.autoReconnect"&gt;true&lt;/property&gt; &lt;property name="connection.autoReconnectForPools"&gt;true&lt;/property&gt; &lt;property name="connection.is-connection-validation-required"&gt;true&lt;/property&gt; &lt;!--&lt;property name="c3p0.min_size"&gt;5&lt;/property&gt; &lt;property name="c3p0.max_size"&gt;20&lt;/property&gt; &lt;property name="c3p0.timeout"&gt;1800&lt;/property&gt; &lt;property name="c3p0.max_statements"&gt;50&lt;/property&gt; --&gt;&lt;property name="hibernate.connection.provider_class"&gt;org.hibernate.connection.C3P0ConnectionProvider &lt;/property&gt; &lt;property name="hibernate.c3p0.acquireRetryAttempts"&gt;30&lt;/property&gt; &lt;property name="hibernate.c3p0.acquireIncrement"&gt;5&lt;/property&gt; &lt;property name="hibernate.c3p0.automaticTestTable"&gt;C3P0TestTable&lt;/property&gt; &lt;property name="hibernate.c3p0.idleConnectionTestPeriod"&gt;36000&lt;/property&gt; &lt;property name="hibernate.c3p0.initialPoolSize"&gt;20&lt;/property&gt; &lt;property name="hibernate.c3p0.maxPoolSize"&gt;100&lt;/property&gt; &lt;property name="hibernate.c3p0.maxIdleTime"&gt;1200&lt;/property&gt; &lt;property name="hibernate.c3p0.maxStatements"&gt;50&lt;/property&gt; &lt;property name="hibernate.c3p0.minPoolSize"&gt;10&lt;/property&gt;--&gt; </code></pre> <p>My connection pooling is occurring fine. During the day it is fine , but once i keep it idle over the night ,next day I find it giving me broken connection error.</p> <p>public class HibernateUtil {</p> <pre><code>private static Logger log = Logger.getLogger(HibernateUtil.class); //private static Log log = LogFactory.getLog(HibernateUtil.class); private static Configuration configuration; private static SessionFactory sessionFactory; static { // Create the initial SessionFactory from the default configuration files try { log.debug("Initializing Hibernate"); // Read hibernate.properties, if present configuration = new Configuration(); // Use annotations: configuration = new AnnotationConfiguration(); // Read hibernate.cfg.xml (has to be present) configuration.configure(); // Build and store (either in JNDI or static variable) rebuildSessionFactory(configuration); log.debug("Hibernate initialized, call HibernateUtil.getSessionFactory()"); } catch (Throwable ex) { // We have to catch Throwable, otherwise we will miss // NoClassDefFoundError and other subclasses of Error log.error("Building SessionFactory failed.", ex); throw new ExceptionInInitializerError(ex); } } /** * Returns the Hibernate configuration that was used to build the SessionFactory. * * @return Configuration */ public static Configuration getConfiguration() { return configuration; } /** * Returns the global SessionFactory either from a static variable or a JNDI lookup. * * @return SessionFactory */ public static SessionFactory getSessionFactory() { String sfName = configuration.getProperty(Environment.SESSION_FACTORY_NAME); System.out.println("Current s name is "+sfName); if ( sfName != null) { System.out.println("Looking up SessionFactory in JNDI"); log.debug("Looking up SessionFactory in JNDI"); try { System.out.println("Returning new sssion factory"); return (SessionFactory) new InitialContext().lookup(sfName); } catch (NamingException ex) { throw new RuntimeException(ex); } } else if (sessionFactory == null) { System.out.println("calling rebuild session factory now"); rebuildSessionFactory(); } return sessionFactory; } /** * Closes the current SessionFactory and releases all resources. * &lt;p&gt; * The only other method that can be called on HibernateUtil * after this one is rebuildSessionFactory(Configuration). */ public static void shutdown() { log.debug("Shutting down Hibernate"); // Close caches and connection pools getSessionFactory().close(); // Clear static variables sessionFactory = null; } /** * Rebuild the SessionFactory with the static Configuration. * &lt;p&gt; * Note that this method should only be used with static SessionFactory * management, not with JNDI or any other external registry. This method also closes * the old static variable SessionFactory before, if it is still open. */ public static void rebuildSessionFactory() { log.debug("Using current Configuration to rebuild SessionFactory"); rebuildSessionFactory(configuration); } /** * Rebuild the SessionFactory with the given Hibernate Configuration. * &lt;p&gt; * HibernateUtil does not configure() the given Configuration object, * it directly calls buildSessionFactory(). This method also closes * the old static variable SessionFactory before, if it is still open. * * @param cfg */ public static void rebuildSessionFactory(Configuration cfg) { log.debug("Rebuilding the SessionFactory from given Configuration"); if (sessionFactory != null &amp;&amp; !sessionFactory.isClosed()) sessionFactory.close(); if (cfg.getProperty(Environment.SESSION_FACTORY_NAME) != null) { log.debug("Managing SessionFactory in JNDI"); cfg.buildSessionFactory(); } else { log.debug("Holding SessionFactory in static variable"); sessionFactory = cfg.buildSessionFactory(); } configuration = cfg; } </code></pre> <p>}</p> <p>Above is my code for the session factory. And I have only select operations .</p> <p>And below is the method which is used most often to execute my select queries. One tricky thing which I am not understanding is in my findById method i am using this line of code getSession().beginTransaction(); without which it gives me an error saying that this cannot happpen without a transaction. But nowhere I am closing this transaction. And thers no method to close a transaction apart from commit or rollback (as far as i know) which are not applicable for select statements.</p> <p>public T findById(ID id, boolean lock) throws HibernateException, DAOException { log.debug("findNyId invoked with ID ="+id+"and lock ="+lock); T entity; getSession().beginTransaction();</p> <pre><code> if (lock) entity = (T) getSession().load(getPersistentClass(), id, LockMode.UPGRADE); else entity = (T) getSession().load(getPersistentClass(), id); return entity; } </code></pre> <p>Can anyone please suggest what can I do ? I have tried out almost every solution available via googling, on stackoverlow or on hibernate forums with no avail. (And increasing wait_timeout on mysql is not a valid option in my case).</p>
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