Instabilidade na conexão

Assuntos Gerais
#1

Olá, pessoal,

Tenho uma aplicação java + Hibernate rodando um servidor glassfish 3.1 na jvn 7.
Minha configuração do hibernate esta no código abaixo.
Tenho ao longo do dia alguns problemas de conexão com o banco, mais a abaixo mostro trechos dos logs do glassfish.

Em resumo o que acontece: Quando mando consultar há momentos que recebo a exception, depois quando tento novamente volta a funcionar.
O que estou fazendo de ERRADO?


<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/xxx?autoReconnect=true</property>
<property name="hibernate.connection.username">xxx</property>
<property name="hibernate.connection.password">xxx</property>

<!-- Enable Hibernate's automatic session context management -->
<property name="current_session_context_class">thread</property>

<!-- Disable the second-level cache  -->
<property name="cache.provider_class">org.hibernate.cache.NoCacheProvider</property>
<property name="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
<property name="hibernate.c3p0.acquire_increment">3</property>
<property name="hibernate.c3p0.min_size">2</property>
<property name="hibernate.c3p0.max_size">20</property>
<property name="hibernate.c3p0.timeout">5000</property>
<property name="hibernate.c3p0.idle_test_period">300</property>
<property name="hibernate.c3p0.max_statements">5</property>
<property name="hibernate.c3p0.validate">true</property>

Log do GlassFish


[#|2013-03-02T10:02:25.661-0300|SEVERE|glassfish3.1.1|javax.enterprise.system.std.com.sun.enterprise.server.logging|_ThreadID=219;_ThreadName=Thread-2;|org.hibernate.exception.JDBCConnectionException: could not execute query
	at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:74)
	at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
	at org.hibernate.loader.Loader.doList(Loader.java:2223)
	at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2104)
	at org.hibernate.loader.Loader.list(Loader.java:2099)
	at org.hibernate.loader.criteria.CriteriaLoader.list(CriteriaLoader.java:94)
	at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1569)
	at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:283)

Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was 44.566.859 milliseconds ago.  The last packet sent successfully to the server was 44.566.860 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.
	at sun.reflect.GeneratedConstructorAccessor586.newInstance(Unknown Source)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:407)
	at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1116)
	at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3358)
	at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1970)
	at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2150)
	at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2626)
	at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2119)
	at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:2281)
	at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.executeQuery(NewProxyPreparedStatement.java:76)
	at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:186)

	... 26 more
Caused by: java.net.SocketException: Broken pipe
	at java.net.SocketOutputStream.socketWrite0(Native Method)
	at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:109)
	at java.net.SocketOutputStream.write(SocketOutputStream.java:153)
	at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
	at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
	at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3339)
	... 37 more
#2