C3P0链接池关闭错误导致的线程问题如何解决

ssh框架下使用c3p0连接池启动tomcat服务器报出如下错误：The web application [RupengElec] appears to have started a thread named [MySQL Statement Cancellation Timer] but has failed to stop it. This is very likely to create a memory leak.
请问这个错误是什么引起的，如何解决？

 <!-- c3p0数据库连接池配置 -->
    <bean name="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="jdbcUrl"
            value="jdbc:mysql://localhost:3306/ElecProject?useUnicode=true&amp;characterEncoding=utf8"></property>
        <property name="driverClass" value="com.mysql.jdbc.Driver"></property>
        <property name="user" value="root"></property>
        <property name="password" value="root"></property>

        <property name="initialPoolSize" value="5"></property>
        <property name="maxPoolSize" value="30"></property>
        <property name="minPoolSize" value="3"></property>
    </bean>

http://blog.csdn.net/killerover84/article/details/48675985