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petter82
 Post subject: 'Database Connection Failure' by using connection pools
PostPosted: Wed Sep 23, 2009 9:51 am 
Newbie

Joined: Tue Sep 22, 2009 4:34 am
Posts: 4
I have a programm, which uses a database on one server to make write operations and a replication of this database is used for reading operations, situated on another server. if I execute a write operation and then a read operation there is thrown the exception posted below.
If I excute my programm only using the write operation or only the read operation, there are no problems, only by switching the server during my running application.
I hope somebody can help me...I already tried very much to solve the problem, but nothing works right now

thank you

the exception:
Code:
org.hibernate.exception.GenericJDBCException: could not load an entity: [mainpackage.Person#67]
   at org.hibernate.exception.ErrorCodeConverter.handledNonSpecificException(ErrorCodeConverter.java:92)
   at org.hibernate.exception.ErrorCodeConverter.convert(ErrorCodeConverter.java:80)
   at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
   at org.hibernate.loader.Loader.loadEntity(Loader.java:1269)
   at org.hibernate.loader.entity.EntityLoader.load(EntityLoader.java:139)
   at org.hibernate.loader.entity.EntityLoader.load(EntityLoader.java:124)
   at org.hibernate.persister.entity.BasicEntityPersister.load(BasicEntityPersister.java:2453)
   at org.hibernate.event.def.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:387)
   at org.hibernate.event.def.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:368)
   at org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:166)
   at org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:140)
   at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:249)
   at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:123)
   at org.hibernate.impl.SessionImpl.get(SessionImpl.java:561)
   at org.hibernate.impl.SessionImpl.get(SessionImpl.java:556)
   at mainpackage.Main.readEntries(Main.java:55)
   at mainpackage.Main.main(Main.java:29)
Caused by: com.mysql.jdbc.CommunicationsException: Communications link failure due to underlying exception:

** BEGIN NESTED EXCEPTION **

java.io.EOFException
MESSAGE: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.

STACKTRACE:

java.io.EOFException: Can not read response from server. Expected to read 4 bytes, read 0 bytes before connection was unexpectedly lost.
   at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1997)
   at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2411)
   at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2916)
   at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1631)
   at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1723)
   at com.mysql.jdbc.Connection.execSQL(Connection.java:3256)
   at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1313)
   at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1448)
   at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:107)
   at org.hibernate.loader.Loader.getResultSet(Loader.java:1183)
   at org.hibernate.loader.Loader.doQuery(Loader.java:363)
   at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:203)
   at org.hibernate.loader.Loader.loadEntity(Loader.java:1255)
   at org.hibernate.loader.entity.EntityLoader.load(EntityLoader.java:139)
   at org.hibernate.loader.entity.EntityLoader.load(EntityLoader.java:124)
   at org.hibernate.persister.entity.BasicEntityPersister.load(BasicEntityPersister.java:2453)
   at org.hibernate.event.def.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:387)
   at org.hibernate.event.def.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:368)
   at org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:166)
   at org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:140)
   at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:249)
   at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:123)
   at org.hibernate.impl.SessionImpl.get(SessionImpl.java:561)
   at org.hibernate.impl.SessionImpl.get(SessionImpl.java:556)
   at mainpackage.Main.readEntries(Main.java:55)
   at mainpackage.Main.main(Main.java:29)


** END NESTED EXCEPTION **



Last packet sent to the server was 4 ms ago.
   at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2622)
   at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2916)
   at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1631)
   at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1723)
   at com.mysql.jdbc.Connection.execSQL(Connection.java:3256)
   at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1313)
   at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1448)
   at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:107)
   at org.hibernate.loader.Loader.getResultSet(Loader.java:1183)
   at org.hibernate.loader.Loader.doQuery(Loader.java:363)
   at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:203)
   at org.hibernate.loader.Loader.loadEntity(Loader.java:1255)
   ... 13 more
Exception in thread "main" org.hibernate.TransactionException: JDBC rollback failed
   at org.hibernate.transaction.JDBCTransaction.rollback(JDBCTransaction.java:142)
   at mainpackage.Main.readEntries(Main.java:72)
   at mainpackage.Main.main(Main.java:29)
Caused by: com.mysql.jdbc.exceptions.MySQLNonTransientConnectionException: Connection.close() has already been called. Invalid operation in this state.
   at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:888)
   at com.mysql.jdbc.Connection.getMutex(Connection.java:3728)
   at com.mysql.jdbc.Connection.rollback(Connection.java:5204)
   at org.hibernate.transaction.JDBCTransaction.rollback(JDBCTransaction.java:134)
   ... 2 more


my main.java
Code:
package mainpackage;


import java.util.List;
import java.io.IOException;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;


public class Main
{
   
   public static void main(String[] args) throws IOException, InterruptedException
   {
      Configuration confRead      = new Configuration();
      SessionFactory sfRead       = confRead.configure("topology3/hibernateRead.cfg.xml").buildSessionFactory();
      confRead    = null;
      
      Configuration confWrite      = new Configuration();
      SessionFactory sfWrite    = confWrite.configure("topology3/hibernateWrite.cfg.xml").buildSessionFactory();
      confWrite    = null;

      
      insertTestPerson( sfWrite ,100 );
      readEntries( sfRead );
      
   }
   
   public static void readEntries( SessionFactory sfRead ) throws IOException
   {
   
      //random value for id
      int randomID;
      
      for( int index = 0; index < 80; index++ )
      {
         randomID = (int)Math.floor( ( Math.random() * 100 ) + 1 );
         
         Session session    = null;
         Transaction tx       = null;
         
         Person person = new Person();
         
         try
         {
            session = sfRead.openSession();
            
            
            tx = session.beginTransaction();
            person = (Person)session.get(Person.class, randomID);
            if( person != null )
            {
               List<Address> addresses = (List)person.getAddresses();
               person.getName();
            }
            else
            {
               System.out.println("NULL" + randomID);
            }
            
            tx.commit();
            
         }
         catch (Exception e)
         {
            e.printStackTrace();
            tx.rollback();
         }
         finally
         {
            session.close();
            session = null;
         }
      }
      
      System.out.println("[Method]::readEntries()");
   }
   
   public static void insertPerson( SessionFactory sfWrite, Person person )
   {

      
      Session session    = null;
      Transaction tx       = null;
      
      try
      {
         session = sfWrite.openSession();
         tx       = session.beginTransaction();
         
         session.save( person ); // Person & Address -> DB
         tx.commit();
      }
      catch (Exception e)
      {
         e.printStackTrace();
         tx.rollback();
      }
      finally
      {
         session.close();
         session = null;
      }
   }
   
   public static void insertTestPerson( SessionFactory sfWrite, int number )
   {
      for( int i = 0; i < number; i++ )
      {
         Address address = new Address();
         address.setZip("0000");
         address.setCity("NOWHERE");
         
         Person person = new Person();
         person.setName("NOBODY");
         person.addAddress( address );
         
         insertPerson( sfWrite, person );
      }
      System.out.println("[Method]::insertTestPerson()");
   }
   
}



the configuration files
hibernateWrite.cfg.xml:
Code:
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
<session-factory>
      <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
      <property name="hibernate.connection.url">jdbc:mysql://188.40.80.213/test_replication_db</property>
      <property name="hibernate.connection.username">user</property>
      <property name="hibernate.connection.password">pw</property>
      <!-- property name="hibernate.connection.pool_size">0</property-->
      <property name="show_sql">false</property>
      <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
      <property name="hibernate.hbm2ddl.auto">create</property>
     
     
                 <property name="hibernate.c3p0.min_size">1</property>
      <property name="hibernate.c3p0.max_size">100</property>
      <property name="hibernate.c3p0.timeout">300</property>
      <property name="hibernate.c3p0.acquire_increment">1</property>
      <property name="hibernate.c3p0.max_statements">50</property>
      <property name="hibernate.c3p0.maxIdleTime">1</property> 
     
      <!-- Mapping files -->
      <mapping resource="mainpackage/Person.hbm.xml"/>
     <mapping resource="mainpackage/Address.hbm.xml"/>

</session-factory>
</hibernate-configuration>


hibernateRead.cfg.xml:
Code:
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
<session-factory>
      <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
      <property name="hibernate.connection.url">jdbc:mysql://188.40.85.136/test_replication_db</property>
      <property name="hibernate.connection.username">user</property>
      <property name="hibernate.connection.password">pw</property>
      <!-- property name="hibernate.connection.pool_size">0</property-->
      <property name="show_sql">false</property>
      <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
      <!-- property to update database pr create a new one; can be 'create' or 'update' -->
      <property name="hibernate.hbm2ddl.auto">update</property>
     
                 <property name="hibernate.c3p0.min_size">1</property>
      <property name="hibernate.c3p0.max_size">100</property>
      <property name="hibernate.c3p0.timeout">300</property>
      <property name="hibernate.c3p0.acquire_increment">1</property>
      <property name="hibernate.c3p0.max_statements">50</property>
      <property name="hibernate.c3p0.maxIdleTime">1</property>
      
      <!-- Mapping files -->
      <mapping resource="mainpackage/Person.hbm.xml"/>
     <mapping resource="mainpackage/Address.hbm.xml"/>

</session-factory>
</hibernate-configuration>
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petter82
 Post subject: Re: 'Database Connection Failure' by using connection pools
PostPosted: Wed Sep 23, 2009 9:54 am 
Newbie

Joined: Tue Sep 22, 2009 4:34 am
Posts: 4
oh sorry,
i forgot to say that my programm works without errors if I don't use connection pools. If I setup the connection pools in the config-files, the error occurs.
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