iam using sakai 2.9.1
after a few operations the server stops responding and prints log:-
2014-02-20 12:48:47,085 WARN http-bio-8080-exec-18 org.sakaiproject.db.impl.BasicSqlService - Sql.dbRead: sql: select SAKAI_SITE.SITE_ID,SAKAI_SITE.TITLE,SAKAI_SITE.TYPE,SAKAI_SITE.SHO
RT_DESC,SAKAI_SITE.DESCRIPTION,SAKAI_SITE.ICON_URL,SAKAI_SITE.INFO_URL,SAKAI_SITE.SKIN,SAKAI_SITE.PUBLISHED,SAKAI_SITE.JOINABLE,SAKAI_SITE.PUBVIEW,SAKAI_SITE.JOIN_ROLE,SAKAI_SITE.IS_SPE
CIAL,SAKAI_SITE.IS_USER,SAKAI_SITE.CREATEDBY,SAKAI_SITE.MODIFIEDBY,SAKAI_SITE.CREATEDON,SAKAI_SITE.MODIFIEDON,SAKAI_SITE.CUSTOM_PAGE_ORDERED,SAKAI_SITE.IS_SOFTLY_DELETED,SAKAI_SITE.SOFT
LY_DELETED_DATE from SAKAI_SITE where ( SITE_ID = ? ) !admin
org.apache.commons.dbcp.SQLNestedException: Cannot get a connection, pool error Timeout waiting for idle object
at org.apache.commons.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:104)
at org.apache.commons.dbcp.BasicDataSource.getConnection(BasicDataSource.java:880)
at org.sakaiproject.db.impl.BasicSqlService.borrowConnection(BasicSqlService.java:260)
at org.sakaiproject.db.impl.BasicSqlService.dbRead(BasicSqlService.java:540)
at org.sakaiproject.util.BaseDbFlatStorage.getResource(BaseDbFlatStorage.java:341)
at org.sakaiproject.util.BaseDbFlatStorage.getResource(BaseDbFlatStorage.java:321)
at org.sakaiproject.site.impl.DbSiteService$DbStorage.get(DbSiteService.java:236)
at org.sakaiproject.site.impl.BaseSiteService.getDefinedSite(BaseSiteService.java:616)
at org.sakaiproject.site.impl.BaseSiteService.getSite(BaseSiteService.java:702)
at org.sakaiproject.site.impl.BaseSiteService.getSiteVisit(BaseSiteService.java:780)
at org.sakaiproject.site.cover.SiteService.getSiteVisit(SiteService.java:140)
at org.sakaiproject.presence.tool.PresenceTool.doGet(PresenceTool.java:141)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.sakaiproject.util.RequestFilter.doFilter(RequestFilter.java:634)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:684)
at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:471)
at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:369)
at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:329)
at org.sakaiproject.tool.impl.ActiveToolComponent$MyActiveTool.forward(ActiveToolComponent.java:511)
at org.sakaiproject.portal.charon.SkinnableCharonPortal.forwardTool(SkinnableCharonPortal.java:1470)
at org.sakaiproject.portal.charon.handlers.PresenceHandler.doPresence(PresenceHandler.java:140)
at org.sakaiproject.portal.charon.handlers.PresenceHandler.doGet(PresenceHandler.java:70)
at org.sakaiproject.portal.charon.SkinnableCharonPortal.doGet(SkinnableCharonPortal.java:881)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:621)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.sakaiproject.util.RequestFilter.doFilter(RequestFilter.java:695)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:224)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:987)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:579)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:307)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.util.NoSuchElementException: Timeout waiting for idle object
at org.apache.commons.pool.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:1167)
at org.apache.commons.dbcp.PoolingDataSource.getConnection(PoolingDataSource.java:96)