Exception after long service execution

modemmisuser · July 22, 2020, 10:28am

I have a screen that allows one to make some selections (which files/entities to import) and then calls a service to do the actual import. This is importing legacy data from our ancient app, so that when clients move to our new (CUBA!) app their data will be there.

This one table/entity in this test case has nearly 9 million records, so it takes a while. (Over 24 hours.)

When it finishes, and it does finish successfully, there is an Exception:

22:23:23.037 ERROR com.haulmont.cuba.web.App               - Error handling exception
Original exception:
java.lang.NullPointerException
	at com.vaadin.ui.ConnectorTracker.removeUnregisteredConnectors(ConnectorTracker.java:426)
	at com.vaadin.ui.ConnectorTracker.cleanConnectorMap(ConnectorTracker.java:288)
	at com.vaadin.ui.ConnectorTracker.cleanConnectorMap(ConnectorTracker.java:276)
	at com.vaadin.server.communication.UidlWriter.write(UidlWriter.java:333)
	at com.vaadin.server.communication.UidlRequestHandler.writeUidl(UidlRequestHandler.java:115)
	at com.vaadin.server.communication.UidlRequestHandler.synchronizedHandleRequest(UidlRequestHandler.java:84)
	at com.vaadin.server.SynchronizedRequestHandler.handleRequest(SynchronizedRequestHandler.java:40)
	at com.vaadin.server.VaadinService.handleRequest(VaadinService.java:1578)
	at com.vaadin.server.VaadinServlet.service(VaadinServlet.java:425)
	at com.haulmont.cuba.web.sys.CubaApplicationServlet.serviceAppRequest(CubaApplicationServlet.java:329)
	at com.haulmont.cuba.web.sys.CubaApplicationServlet.service(CubaApplicationServlet.java:215)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.CompositeFilter$VirtualFilterChain.doFilter(CompositeFilter.java:108)
	at org.springframework.web.filter.CompositeFilter.doFilter(CompositeFilter.java:74)
	at com.haulmont.cuba.web.sys.CubaHttpFilter.doFilter(CubaHttpFilter.java:93)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at com.haulmont.cuba.web.sys.singleapp.SingleAppWebContextLoader$SetClassLoaderFilter.doFilter(SingleAppWebContextLoader.java:257)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:690)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.base/java.lang.Thread.run(Thread.java:834)

Exception in handlers:
java.lang.NullPointerException
	at com.vaadin.server.Page.getWebBrowser(Page.java:765)
	at com.haulmont.cuba.web.widgets.CubaCopyButtonExtension.browserSupportCopy(CubaCopyButtonExtension.java:104)
	at com.haulmont.cuba.web.exception.ExceptionDialog.(ExceptionDialog.java:173)
	at com.haulmont.cuba.web.exception.ExceptionDialog.(ExceptionDialog.java:88)
	at com.haulmont.cuba.web.exception.DefaultExceptionHandler.showDialog(DefaultExceptionHandler.java:85)
	at com.haulmont.cuba.web.exception.DefaultExceptionHandler.handle(DefaultExceptionHandler.java:70)
	at com.haulmont.cuba.web.exception.ExceptionHandlers.handle(ExceptionHandlers.java:121)
	at com.haulmont.cuba.web.App.lambda$init$1840d7d1$1(App.java:238)
	at com.vaadin.server.VaadinService.handleExceptionDuringRequest(VaadinService.java:1607)
	at com.vaadin.server.VaadinService.handleRequest(VaadinService.java:1590)
	at com.vaadin.server.VaadinServlet.service(VaadinServlet.java:425)
	at com.haulmont.cuba.web.sys.CubaApplicationServlet.serviceAppRequest(CubaApplicationServlet.java:329)
	at com.haulmont.cuba.web.sys.CubaApplicationServlet.service(CubaApplicationServlet.java:215)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.CompositeFilter$VirtualFilterChain.doFilter(CompositeFilter.java:108)
	at org.springframework.web.filter.CompositeFilter.doFilter(CompositeFilter.java:74)
	at com.haulmont.cuba.web.sys.CubaHttpFilter.doFilter(CubaHttpFilter.java:93)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at com.haulmont.cuba.web.sys.singleapp.SingleAppWebContextLoader$SetClassLoaderFilter.doFilter(SingleAppWebContextLoader.java:257)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:690)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:373)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1590)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.base/java.lang.Thread.run(Thread.java:834)

Any clues as to how to resolve this? It’s not critical I suppose since data import isn’t user-facing, but I’d still like to fix it if possible!

albudarov · July 24, 2020, 6:51am

Hi,
Probably this error occurs because after 24h the web session has been removed. This error does not do any harm.
Considering that importing legacy data from legacy app is a one-time operation - I would leave everything as is.

If such operation would be a usual use case of the application - it would have to be re-implemented to avoid launching long synchronous operation from UI.

modemmisuser · July 24, 2020, 10:37am

That is kind of what I thought - thank you for the answer @AlexBudarov.

If it becomes necessary, how would one proceed to re-implement the functionality?

peterson.br · July 24, 2020, 11:35am

Hi @jon.craig,
A possible solution is to use scheduled tasks. After the user select what he wants to import you can change something (a status field, for example) so that the next time the scheduled task runs it can start the actual long running process.

This solution is used when you send Async Emails, for example.

Another benefit is that you are able to introduce “checkpoints” in your long running process as well (to inform the user how is the process and to recover from failures - not having to restart the whole process).

Regards,
Peterson.