[WARNING] / java.lang.AssertionError occur very often

Roberto2 · April 8, 2020, 12:50pm

Hi,

very often I get the error at the bottom, I have assertions enabled.
When it happens even reloading the page the error is thrown again and connecting with other clients too.

What does it means?

Thanks for the help

[WARNING]
 /
java.lang.AssertionError
	at com.vaadin.flow.server.VaadinService.requestEnd(VaadinService.java:1471)
	at com.vaadin.flow.server.VaadinService.handleRequest(VaadinService.java:1554)
	at com.vaadin.flow.server.VaadinServlet.service(VaadinServlet.java:247)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
	at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:755)
	at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:547)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
	at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:590)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:235)
	at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1610)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:233)
	at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1300)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:188)
	at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:485)
	at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1580)
	at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:186)
	at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1215)
	at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
	at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:221)
	at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:146)
	at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
	at org.eclipse.jetty.server.Server.handle(Server.java:500)
	at org.eclipse.jetty.server.HttpChannel.lambda$handle$1(HttpChannel.java:383)
	at org.eclipse.jetty.server.HttpChannel.dispatch(HttpChannel.java:547)
	at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:375)
	at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:273)
	at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:311)
	at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:103)
	at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:117)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:336)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:313)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:171)
	at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:129)
	at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:375)
	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:806)
	at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:938)
	at java.lang.Thread.run(Thread.java:748)

Roberto2 · April 11, 2020, 4:09pm

After this error is thrown for the first time the application has to be restarted.
It continues to thrown the same assertion error for every client and I get other exceptions that for sure are related to it, like the one I copy at the bottom.

What can cause it ? Just to give an idea, where to look. I am new to Vaadin.
In exception stracktrace I don’t see a line related to my code.
It doesn’t happen every time but, as I wrote, often.
What I am doing related to session is saving some data on VaadinSession and I am using VaadinRequest, VaadinResponse to save some cookies and I am using push too.

I get the VaadinSession instance via VaadinSession.getCurrent() and request/response via:

		HttpServletRequest request =
			    (HttpServletRequest) VaadinRequest.getCurrent();
		
		HttpServletResponse response = 
				(HttpServletResponse) VaadinResponse.getCurrent();

2020-04-11 18:06:14,847 [Atmosphere-Shared-109]
 ERROR c.v.f.s.c.PushAtmosphereHandler - Exception in push connection
org.eclipse.jetty.io.EofException: null
        at org.eclipse.jetty.server.HttpConnection$SendCallback.reset(HttpConnection.java:728)
        at org.eclipse.jetty.server.HttpConnection$SendCallback.access$300(HttpConnection.java:688)
        at org.eclipse.jetty.server.HttpConnection.send(HttpConnection.java:547)
        at org.eclipse.jetty.server.HttpChannel.sendResponse(HttpChannel.java:824)
        at org.eclipse.jetty.server.HttpChannel.write(HttpChannel.java:901)
        at org.eclipse.jetty.server.HttpOutput.channelWrite(HttpOutput.java:283)
        at org.eclipse.jetty.server.HttpOutput.channelWrite(HttpOutput.java:267)
        at org.eclipse.jetty.server.HttpOutput.flush(HttpOutput.java:705)
        at org.eclipse.jetty.server.Response.flushBuffer(Response.java:1057)
        at javax.servlet.ServletResponseWrapper.flushBuffer(ServletResponseWrapper.java:215)
        at org.atmosphere.cpr.AtmosphereResponseImpl.flushBuffer(AtmosphereResponseImpl.java:506)
        at org.atmosphere.cpr.AtmosphereInterceptorWriter.flush(AtmosphereInterceptorWriter.java:102)
        at org.atmosphere.cpr.AtmosphereResponseImpl$Stream.flush(AtmosphereResponseImpl.java:1001)
        at org.atmosphere.handler.AbstractReflectorAtmosphereHandler.onStateChange(AbstractReflectorAtmosphereHandler.java:156)
        at com.vaadin.flow.server.communication.PushAtmosphereHandler.onStateChange(PushAtmosphereHandler.java:52)
        at org.atmosphere.cpr.DefaultBroadcaster.invokeOnStateChange(DefaultBroadcaster.java:1037)
        at org.atmosphere.cpr.DefaultBroadcaster.prepareInvokeOnStateChange(DefaultBroadcaster.java:1057)
        at org.atmosphere.cpr.DefaultBroadcaster.executeAsyncWrite(DefaultBroadcaster.java:871)
        at org.atmosphere.cpr.DefaultBroadcaster$2.run(DefaultBroadcaster.java:474)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)
2020-04-11 18:06:19,901 [qtp720594991-195]
 WARN  c.v.f.s.c.ServerRpcHandler - Resynchronizing UI by client's request. Under normal operations this should not happen and may indicate a bug in Vaadin platform. If you see this message regularly please open a bug report at https://github.com/vaadin/flow/issues