查了好多资料，还是找不到原因呀！！！
有人说去掉<property name="checkoutTimeout" value="18000" />，其实等于没做一样，无非是不报异常了，该连接不上还是连接不上！
也有人说<property name="maxPoolSize" value="1200"/>把这个改大一些，你看我这1200不小了吧！
还有人说<property name="acquireIncrement" value="10"/>把这个改成5，默认是3，我都改成10了，也够了吧！
我是tomcat集群配置，两个项目的spring配置文件一模一样，但是只有其中的一个经常报此异常！
怎么解决呀？？？
2011-11-23 10:41:59 org.hibernate.util.JDBCExceptionReporter logExceptions
警告: SQL Error: 0, SQLState: null
2011-11-23 10:41:59 org.hibernate.util.JDBCExceptionReporter logExceptions
严重: An attempt by a client to checkout a Connection has timed out.
2011-11-23 10:41:59 org.hibernate.util.JDBCExceptionReporter logExceptions
警告: SQL Error: 0, SQLState: null
2011-11-23 10:41:59 org.hibernate.util.JDBCExceptionReporter logExceptions
严重: An attempt by a client to checkout a Connection has timed out.
2011-11-23 10:41:59 org.hibernate.event.def.DefaultLoadEventListener onLoad
信息: Error performing load command
org.hibernate.exception.GenericJDBCException: Cannot open connection
at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:140)
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:128)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:52)
at org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:449)
at org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:167)
at org.hibernate.jdbc.AbstractBatcher.prepareQueryStatement(AbstractBatcher.java:161)
at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1596)
at org.hibernate.loader.Loader.doQuery(Loader.java:717)
at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:270)
at org.hibernate.loader.Loader.loadEntity(Loader.java:1933)
at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:86)
at org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:76)
at org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:3270)
at org.hibernate.event.def.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:496)
at org.hibernate.event.def.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:477)
at org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:227)
at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:285)
at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:152)
at org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:1080)
at org.hibernate.impl.SessionImpl.get(SessionImpl.java:997)
at org.hibernate.impl.SessionImpl.get(SessionImpl.java:990)
at org.springframework.orm.hibernate3.HibernateTemplate$1.doInHibernate(HibernateTemplate.java:531)
at org.springframework.orm.hibernate3.HibernateTemplate.doExecute(HibernateTemplate.java:419)
at org.springframework.orm.hibernate3.HibernateTemplate.executeWithNativeSession(HibernateTemplate.java:374)
at org.springframework.orm.hibernate3.HibernateTemplate.get(HibernateTemplate.java:525)
at org.springframework.orm.hibernate3.HibernateTemplate.get(HibernateTemplate.java:519)
at com.ks.dao.ClassDAO.findByIdString(ClassDAO.java:322)
at com.ks.service.CommonService.findByIdString(CommonService.java:99)
at sun.reflect.GeneratedMethodAccessor95.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:307)
at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:182)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:89)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
at $Proxy43.findByIdString(Unknown Source)
at com.ks.interceptor.FormTemplateInterceptor.intercept(FormTemplateInterceptor.java:155)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:165)
at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
...
Caused by: java.sql.SQLException: An attempt by a client to checkout a Connection has timed out.