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

Question

I have an Spring application with quartz scheduler for batch processing. It was working fine from last 4 years. There is a batch which runs on every 1 minute. But from last few days suddenly when the batch is trying to fetch some data we are getting org.springframework.transaction.CannotCreateTransactionException: Could not open Hibernate Session for transaction; nested exception is org.hibernate.exception.JDBCConnectionException: Could not open connection org.springframework.transaction.CannotCreateTransactionException: Could not open Hibernate Session for transaction; nested exception is org.hibernate.exception.JDBCConnectionException: Could not open connection

This batch runs throughout the day but some times gives this exception and all other batches fails to connect to MySQL. So we are restarting the application and it is working fine.

Data source config

<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="url">
            <value>${DATABASE_URL}</value>
        </property>
        <property name="driverClassName">
            <value>com.mysql.jdbc.Driver</value>
        </property>
        <property name="username">
            <value>${DATABASE_USER}</value>
        </property>
        <property name="password">
            <value>${DATABASE_PASSWORD}</value>
        </property>
</bean>

Session factory connection pooling configuration

<bean id="sessionFactory"
        class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
<prop key="hibernate.show_sql">false</prop>
<prop key="hibernate.enable_lazy_load_no_trans">true</prop>
<!-- Configurations specific to c3p0 connection pooling -->

<prop key="hibernate.c3p0.acquire_increment">5</prop>
<prop key="hibernate.c3p0.idle_test_period">1800</prop>
<prop key="hibernate.c3p0.max_size">600</prop>
<prop key="hibernate.c3p0.max_statements">50</prop>
<prop key="hibernate.c3p0.min_size">5</prop>
<prop key="hibernate.c3p0.timeout">1800</prop>
</props>
</property>
<property name="annotatedClasses">
<list> .... </list>
</property>
</bean>

Answer 1

May be it is the problem with the mysql running your db-server.

change the mysql configuration in your db-server

add the bind-address in mysql.cnf under [mysqld] section

bind-address=your_spring_application_ip

also change the accessing host for the mysql user. run the following query in mysql

update mysql.user set host='%' where user='your_username';
flush privileges;

then restart the mysql service

sudo systemctl restart mysql

Answer 2

Recently we had kind of the same issue. Our application failed to connect to aws Aurora instance. What we ended up doing changing sql driver to mariadb one. Hope this will help.