Hibernate JDBCExceptionReporter -> Connection validity, timeout, auto reconnect
<hibernate-configuration>
    <session-factory>
        <!-- Database connection settings -->
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost/mydbtest</property>
        <property name="connection.username">root</property>
        <property name="connection.password">mypassword</property>
        <!-- JDBC connection pool (use the built-in) -->
        <property name="connection.pool_size">20</property>
        <!-- SQL dialect -->
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
        <!-- Enable Hibernate's automatic session context management, in this case
             the session will be close after each transaction! -->
        <property name="current_session_context_class">thread</property>
        <!-- Disable the second-level cache -->
        <property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>
        <!-- auto create tables -->
        <property name="hbm2ddl.auto">none</property>
        ...
    </session-factory>
</hibernate-configuration>

Hibernate: select ...
WARN : org.hibernate.util.JDBCExceptionReporter - SQL Error: 0, SQLState: 08S01
ERROR: org.hibernate.util.JDBCExceptionReporter -
       The last packet successfully received from the server was 61.428.729
       milliseconds ago.  The last packet sent successfully to the server was
       61.428. milliseconds ago. is longer than the server configured value of
       'wait_timeout'. You should consider either expiring and/or testing
       connection validity before use in your application, increasing the server
       configured values for client timeouts, or using the Connector/J
       connection property 'autoReconnect=true' to avoid this problem.

<property name=“hibernate.c3p0.acquire_increment”>3</property>
<property name=“hibernate.c3p0.idle_test_period”>14400</property>
<property name=“hibernate.c3p0.timeout”>25200</property>
<property name=“hibernate.c3p0.max_size”>15</property>
<property name=“hibernate.c3p0.min_size”>3</property>
<property name=“hibernate.c3p0.max_statements”>0</property>
<property name=“hibernate.c3p0.preferredTestQuery”>select 1;</property>

[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid