AbstractCommunicationManager.doHandleUidlRequest() blocked thread

In our application after about 24 hours uptime (sometimes more), I find some threads blocked causing useless CPU load.
Here is a part of thread dump. Any ideas?

"ajp-192.168.189.58-8009-20" - Thread t@826
   java.lang.Thread.State: BLOCKED
	at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.doHandleUidlRequest(AbstractCommunicationManager.java:747)
	- waiting to lock :love:f5b5e0c> (a com.apps.ccs.MyApplication) owned by "ajp-192.168.189.58-8009-5" t@175
	at com.vaadin.terminal.gwt.server.CommunicationManager.handleUidlRequest(CommunicationManager.java:296)
	at com.vaadin.terminal.gwt.server.AbstractApplicationServlet.service(AbstractApplicationServlet.java:501)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:235)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
	at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:190)
	at org.jboss.modcluster.catalina.CatalinaContext$RequestListenerValve.event(CatalinaContext.java:285)
	at org.jboss.modcluster.catalina.CatalinaContext$RequestListenerValve.invoke(CatalinaContext.java:261)
	at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:92)
	at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.process(SecurityContextEstablishmentValve.java:126)
	at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:70)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
	at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:330)
	at org.apache.coyote.ajp.AjpAprProcessor.process(AjpAprProcessor.java:419)
	at org.apache.coyote.ajp.AjpAprProtocol$AjpConnectionHandler.process(AjpAprProtocol.java:402)
	at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:2036)
	at java.lang.Thread.run(Thread.java:662)

And here is the thread that locked Application object

"ajp-192.168.189.68-8009-5" - Thread t@175
   java.lang.Thread.State: RUNNABLE
	at java.util.HashMap.put(HashMap.java:374)
	at java.util.HashSet.add(HashSet.java:200)
	at com.vaadin.ui.Table.listenProperty(Table.java:1931)
	at com.vaadin.ui.Table.getVisibleCellsNoCache(Table.java:1863)
	at com.vaadin.ui.Table.refreshRenderedCells(Table.java:1477)
	at com.vaadin.ui.Table.getVisibleCells(Table.java:3390)
	at com.vaadin.ui.Table.paintContent(Table.java:2665)
	at com.vaadin.ui.AbstractComponent.paint(AbstractComponent.java:781)
	at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.writeUidlResponce(AbstractCommunicationManager.java:1040)
	at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.paintAfterVariableChanges(AbstractCommunicationManager.java:927)
	at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.doHandleUidlRequest(AbstractCommunicationManager.java:794)
	- locked :love:f5b5e0c> (a com.apps.ccs.MyApplication)
	at com.vaadin.terminal.gwt.server.CommunicationManager.handleUidlRequest(CommunicationManager.java:296)
	at com.vaadin.terminal.gwt.server.AbstractApplicationServlet.service(AbstractApplicationServlet.java:501)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:235)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
	at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:190)
	at org.jboss.modcluster.catalina.CatalinaContext$RequestListenerValve.event(CatalinaContext.java:285)
	at org.jboss.modcluster.catalina.CatalinaContext$RequestListenerValve.invoke(CatalinaContext.java:261)
	at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:92)
	at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.process(SecurityContextEstablishmentValve.java:126)
	at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:70)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
	at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:330)
	at org.apache.coyote.ajp.AjpAprProcessor.process(AjpAprProcessor.java:419)
	at org.apache.coyote.ajp.AjpAprProtocol$AjpConnectionHandler.process(AjpAprProtocol.java:402)
	at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:2036)
	at java.lang.Thread.run(Thread.java:662)