Vaadin23 PUSH UIDetachedException

Question

I have the following broadcast handler in the MainLayout

@Override
protected void onAttach(AttachEvent attachEvent) {
    super.onAttach(attachEvent);

    SecurityService securityService = serviceFacade.getSecurityService();
    UI ui = attachEvent.getUI();
    if (securityService.isAuthorized()) {
        broadcasterRegistration = serviceFacade.getBroadcasterService().register(securityService.getCurrentUserUuid(), broadcasterMessage -> {
            ui.access(() -> {
                processBroadcasterMessage(broadcasterMessage);
            });
        });
    }
}

and from time to time I see the following exception in the logs:

Exception in thread "pool-3-thread-5" com.vaadin.flow.component.UIDetachedException
    at com.vaadin.flow.component.UI.handleAccessDetach(UI.java:415)
    at com.vaadin.flow.component.UI.access(UI.java:515)
    at com.vaadin.flow.component.UI.access(UI.java:502)
    at com.example.ui.layout.MainLayout.lambda$onAttach$2(MainLayout.java:331)
    at com.example.ui.service.broadcaster.BroadcasterServiceImpl.lambda$broadcast$0(BroadcasterServiceImpl.java:46)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
    at java.base/java.lang.Thread.run(Thread.java:833)

Despite the fact of this exception everything works properly, so my question is - should I react somehow on this UIDetachedException exception or not?

score 1 · Accepted Answer · answered Sep 28 '22 at 16:47

1

UIDetachedException serves a purpose. It is thrown when you attempt to access closed UI. User has closed the Browser. You should catch the exception, e.g. stop the background task, unregister the broadcast listener.

answered Sep 28 '22 at 16:47

Tatu Lund

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Thanks for your answer! Could you please tell the scenario how to reproduce it locally? I can't reproduce it to handle it ( – alexanoid Sep 28 '22 at 18:41
1

Could you just check UI#isAttached inside of the #access class instead of catching the exception? – Roman Kovařík Sep 29 '22 at 12:17
sure, thanks! I'll add this check also – alexanoid Sep 30 '22 at 21:29

Vaadin23 PUSH UIDetachedException

1 Answers1