MysqL服务器默认的“wait_timeout”是8小时，也就是说一个connection空闲超过8个小时，MysqL将自动断开该connection。
There is a solution introduced in the Pentaho forum for this,you can find the thread with the following link.
http://forums.pentaho.com/showthread.PHP?54939-Pentaho-Server-falls-each-night-..&p=178067#post178067
But above forum post is based on the JBoss server. My intention with this post is to implement the same on the tomcat server since the file structure is a bit different. Ok without further due,let get into action.
01. Download the C3P0 driver from SourceForge
02. Extract the c3p0-0.9.1.2.jar file into \biserver-ce\tomcat\common\lib\
03. Open the MysqL5.hibernate.cfg.xml XML file in the \biserver-ce\pentaho-solutions\system\hibernate\ folder
04. Add the following code into the file
<!— hibernate c3p0 settings —> <property name=”connection.provider_class”>org.hibernate.connection.C3P0ConnectionProvider</property> <property name=”hibernate.c3p0.acquire_increment”>3</property> <property name=”hibernate.c3p0.idle_test_period”>10</property> <property name=”hibernate.c3p0.min_size”>5</property> <property name=”hibernate.c3p0.max_size”>75</property> <property name=”hibernate.c3p0.max_statements”>0</property> <property name=”hibernate.c3p0.timeout”>25200</property> <property name=”hibernate.c3p0.preferredTestQuery”>select 1</property> <property name=”hibernate.c3p0.testConnectionOnCheckout”>true</property>
