Ajax queues concurrency woes
m.a.knapp Jul 29, 2009 11:08 AMI noticed that concurrent ajax events may interfere each other, then several exceptions pop up like:
16:49:58,031 ERROR [[facesservlet]] Servlet.service() for servlet facesservlet threw exception java.lang.ArrayIndexOutOfBoundsException: -1 at java.util.ArrayList.fastRemove(ArrayList.java:441) at java.util.ArrayList.remove(ArrayList.java:424) at javax.faces.component.UIComponentBase$AttributesMap.remove(UIComponentBase.java:1695) at com.sun.facelets.tag.jsf.ComponentSupport.finalizeForDeletion(ComponentSupport.java:54) at com.sun.facelets.tag.jsf.ComponentHandler.apply(ComponentHandler.java:173) at com.sun.facelets.tag.jsf.ComponentHandler.applyNextHandler(ComponentHandler.java:314) at com.sun.facelets.tag.jsf.ComponentHandler.apply(ComponentHandler.java:169) at com.sun.facelets.tag.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:47) at com.sun.facelets.tag.jsf.ComponentHandler.applyNextHandler(ComponentHandler.java:314) at com.sun.facelets.tag.jsf.ComponentHandler.apply(ComponentHandler.java:169) at com.sun.facelets.tag.jsf.ComponentHandler.applyNextHandler(ComponentHandler.java:314) at com.sun.facelets.tag.jsf.ComponentHandler.apply(ComponentHandler.java:169) at com.sun.facelets.tag.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:47) at com.sun.facelets.tag.jsf.core.ViewHandler.apply(ViewHandler.java:109) at com.sun.facelets.tag.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:47) at com.sun.facelets.compiler.NamespaceHandler.apply(NamespaceHandler.java:49) at com.sun.facelets.tag.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:47) at com.sun.facelets.compiler.EncodingHandler.apply(EncodingHandler.java:25) at com.sun.facelets.impl.DefaultFacelet.apply(DefaultFacelet.java:95) at com.sun.facelets.FaceletViewHandler.buildView(FaceletViewHandler.java:524) at com.sun.facelets.FaceletViewHandler.renderView(FaceletViewHandler.java:567) at org.ajax4jsf.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:100) at org.ajax4jsf.application.AjaxViewHandler.renderView(AjaxViewHandler.java:176) at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:110) at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100) at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139) at javax.faces.webapp.FacesServlet.service(FacesServlet.java:266)
and
16:47:48,515 WARN [lifecycle] JSF1053: (Listener: org.ajax4jsf.event.AjaxPhaseListener.afterPhase(), Phase ID: RESTORE_VIEW 1, View ID: /queuetest.jsf) Exception thrown during phase-listener executi on: java.util.ConcurrentModificationException 16:47:48,515 WARN [lifecycle] java.util.HashMap$HashIterator.nextEntry(HashMap.java:793) java.util.HashMap$KeyIterator.next(HashMap.java:828) org.ajax4jsf.event.AjaxPhaseListener.afterPhase(AjaxPhaseListener.java:79) com.sun.faces.lifecycle.Phase.handleAfterPhase(Phase.java:175) com.sun.faces.lifecycle.Phase.doPhase(Phase.java:114) com.sun.faces.lifecycle.RestoreViewPhase.doPhase(RestoreViewPhase.java:103) com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118) javax.faces.webapp.FacesServlet.service(FacesServlet.java:265) org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:510) org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:178) org.ajax4jsf.webapp.BaseFilter.handleRequest(BaseFilter.java:290) org.ajax4jsf.webapp.BaseFilter.processUploadsAndHandleRequest(BaseFilter.java:368) org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:495) org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96) org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235) org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230) org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175) org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:182) org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:524) org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84) org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:157) org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:262) org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844) org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583) org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:446) java.lang.Thread.run(Thread.java:619)
I have created an implemented an example to show this problem.
This example crashes after a short time with the exceptions above
JSF code
<f:view> <a4j:region> <a4j:form> <a4j:queue name="queue1" /> <a4j:queue name="queue2" /> <a4j:jsFunction name="doCount1" actionListener="#{test.doCount1}" eventsQueue="queue1" reRender="count1" ajaxSingle="true" /> <a4j:jsFunction name="doCount2" actionListener="#{test.doCount2}" eventsQueue="queue2" reRender="count2" ajaxSingle="true" /> <a4j:outputPanel layout="block" id="count1" > <h:outputText value="Count 1 : #{test.count1}" /> </a4j:outputPanel> <a4j:outputPanel layout="block" id="count2" > <h:outputText value="Count 2 : #{test.count2}" /> </a4j:outputPanel> <a4j:outputPanel layout="block" id="counts" > <h:outputText value="Count 1 : #{test.count1}" /> <br /> <h:outputText value="Count 2 : #{test.count2}" /> </a4j:outputPanel> <script type="text/javascript" > window.setInterval('doCount1()', 50); window.setInterval('doCount2()', 50); </script> </a4j:form> </a4j:region> <a4j:region> <a4j:form id="PollForm" > <a4j:poll id="poll" interval="100" reRender="counts" /> </a4j:form> </a4j:region> </f:view>
Bean code
public class TestBean { private int count1 = 0; private int count2 = 0; public void doCount1(ActionEvent event) { count1++; try { Thread.sleep((int)(Math.random() * 50)); } catch (InterruptedException e) { e.printStackTrace(); } } public void doCount2(ActionEvent event) { count2++; try { Thread.sleep((int)(Math.random() * 50)); } catch (InterruptedException e) { e.printStackTrace(); } } public int getCount1() { return count1; } public int getCount2() { return count2; } }