oracle.toplink.essentials.exceptions.DatabaseException
Internal Exception: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

Oracle TopLink Essentials - 2.0.1

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
  <persistence-unit name="FrTreePU2" transaction-type="RESOURCE_LOCAL">
    <provider>oracle.toplink.essentials.PersistenceProvider</provider>
    <class>frtree.City</class>
    <class>frtree.Company</class>
    <class>frtree.Contacts</class>
    <class>frtree.Groupcontact</class>
    <class>frtree.Grouptovar</class>
    <properties>
      <property name="toplink.jdbc.user" value="zzzz"/>
      <property name="toplink.jdbc.password" value="zzzz"/>
      <property name="toplink.jdbc.url" value="jdbc:mysql://zzzzzz:3306/zzzzz"/>
      <property name="toplink.jdbc.driver" value="com.mysql.jdbc.Driver"/>
    </properties>
  </persistence-unit>
</persistence>

autoReconnect=true

<property name="toplink.jdbc.url" value="jdbc:mysql://ip:3306/nameDB?autoReconnect=true"/>

ComboPooledDataSource cpds = new ComboPooledDataSource();
cpds.setDriverClass( "com.mysql.jdbc.Driver" );             
cpds.setJdbcUrl( "jdbc:mysql://ip:3306/nameDB" );
cpds.setUser("user");                                  
cpds.setPassword("pass");                                  
	
cpds.setMinPoolSize(5);                                     
cpds.setAcquireIncrement(5);
cpds.setMaxPoolSize(20);