mysql 跟连接池的问题

以前还没有这样的问题，现在频繁出现,
java.sql.SQLException: Got error 12 from storage engine
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:946)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2870)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1573)
at com.mysql.jdbc.ServerPreparedStatement.serverExecute(ServerPreparedStatement.java:1160)
at com.mysql.jdbc.ServerPreparedStatement.executeInternal(ServerPreparedStatement.java:685)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1262)
at sun.reflect.GeneratedMethodAccessor54.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.logicalcobwebs.proxool.ProxyStatement.invoke(ProxyStatement.java:100)
at org.logicalcobwebs.proxool.ProxyStatement.intercept(ProxyStatement.java:57)
at $java.sql.PreparedStatement$$EnhancerByCGLIB$$6c344add.executeQuery(<generated>)
at sys.DisplayDAO.FindCategoryList(DisplayDAO.java:85)
at sys.taglibs.jDOMXmlTag.doEndTag(jDOMXmlTag.java:217)
at _jsp._member._xmlOutput__jsp._jspService(_xmlOutput__jsp.java:305)
at com.caucho.jsp.JavaPage.service(JavaPage.java:60)
at com.caucho.jsp.Page.pageservice(Page.java:570)
at com.caucho.server.dispatch.PageFilterChain.doFilter(PageFilterChain.java:175)
at com.caucho.server.webapp.DispatchFilterChain.doFilter(DispatchFilterChain.java:115)
at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:229)
at com.caucho.server.webapp.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:277)
at com.caucho.server.webapp.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:106)
at org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1085)
at org.apache.struts.tiles.TilesRequestProcessor.doForward(TilesRequestProcessor.java:263)
at org.apache.struts.action.RequestProcessor.internalModuleRelativeForward(RequestProcessor.java:1023)
at org.apache.struts.tiles.TilesRequestProcessor.internalModuleRelativeForward(TilesRequestProcessor.java:345)
at org.apache.struts.action.RequestProcessor.processForward(RequestProcessor.java:572)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:221)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1196)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:115)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:92)
at com.caucho.server.dispatch.ServletFilterChain.doFilter(ServletFilterChain.java:106)
at sys.function.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:78)
at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
at com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFilterChain.java:178)
at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:229)
at com.caucho.server.hmux.HmuxRequest.handleRequest(HmuxRequest.java:419)
at com.caucho.server.port.TcpConnection.run(TcpConnection.java:389)
at com.caucho.util.ThreadPool.runTasks(ThreadPool.java:507)
at com.caucho.util.ThreadPool.run(ThreadPool.java:433)
at java.lang.Thread.run(Thread.java:595)