URGENT: ConcurrentModificationException

Vaadin 6 / 7 / 8 Framework UI
1

Can anybody suggest why am I getting this exception and how to fix this?

java.util.ConcurrentModificationException
at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
at java.util.AbstractList$Itr.next(AbstractList.java:343)
at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.getDirtyVisibleComponents(AbstractCommunicationManager.java:1891)
at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.writeUidlResponce(AbstractCommunicationManager.java:891)
at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.paintAfterVariableChanges(AbstractCommunicationManager.java:836)
at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.doHandleUidlRequest(AbstractCommunicationManager.java:762)
at com.vaadin.terminal.gwt.server.CommunicationManager.handleUidlRequest(CommunicationManager.java:296)
at com.vaadin.terminal.gwt.server.AbstractApplicationServlet.service(AbstractApplicationServlet.java:483)
at org.vaadin.artur.icepush.ICEPushServlet.service(ICEPushServlet.java:40)
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 com.foo.filter.FooFilter.doFilter(FooFilter.java:64)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at com.planetj.servlet.filter.compression.CompressingFilter.doFilter(CompressingFilter.java:270)
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:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:470)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Thread.java:680)

thanks
dheeraj

2

You are likely changing elements in the user interface from “underneath”. In other words, a background thread, a callback, a timer, or activity in another session, results in a change to the user interface. When you do things like that, you need to enclose your code in a synchronized(getApplication()) {} block so that the threads don’t interfere with one another.