NPE from Wicket Atmospere support when shutting down Tomcat

[0xabadea]

Bonjour,

We get this when shutting down Tomcat:

    java.lang.NullPointerException: null
        at org.apache.wicket.atmosphere.EventBus.get(EventBus.java:86)
        at org.apache.wicket.atmosphere.AtmosphereBehavior.findEventBus(AtmosphereBehavior.java:85)
        at org.apache.wicket.atmosphere.AtmosphereBehavior.onDisconnect(AtmosphereBehavior.java:182)
        at org.atmosphere.cpr.AtmosphereResourceImpl.onDisconnect(AtmosphereResourceImpl.java:809)
        at org.atmosphere.cpr.AtmosphereResourceImpl.notifyListeners(AtmosphereResourceImpl.java:754)
        at org.atmosphere.cpr.AtmosphereResourceImpl.resume(AtmosphereResourceImpl.java:327)
        at org.atmosphere.cpr.DefaultBroadcaster.resumeAll(DefaultBroadcaster.java:315)
        at org.atmosphere.cpr.DefaultBroadcasterFactory.destroy(DefaultBroadcasterFactory.java:307)
        at org.atmosphere.cpr.AtmosphereFramework.destroy(AtmosphereFramework.java:930)
        at org.atmosphere.cpr.AtmosphereServlet.destroy(AtmosphereServlet.java:186)
        at org.apache.catalina.core.StandardWrapper.unload(StandardWrapper.java:1465)
        at org.apache.catalina.core.StandardWrapper.stopInternal(StandardWrapper.java:1823)
        at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:232)
        at org.apache.catalina.core.StandardContext.stopInternal(StandardContext.java:5463)
        at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:232)
        at org.apache.catalina.core.ContainerBase$StopChild.call(ContainerBase.java:1575)
        at org.apache.catalina.core.ContainerBase$StopChild.call(ContainerBase.java:1564)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
        at java.util.concurrent.FutureTask.run(FutureTask.java:138)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
        at java.lang.Thread.run(Thread.java:662)

I am filing this against Atmosphere and not the Wicket support because it doesn't seem to me that the Wicket support is at fault.

The NPE occurs because the Wicket application has already been destroyed. It it destroyed by the Wicket filter's destroy() method, which is invoked by ReflectorServletProcessor.destroy(). AtmosphereFramework.destroy() first destroys the handler, and then it destroys the broadcast factory (which resumes the resources). Is this correct?

If I'm wrong, could you please suggest what the Wicket support could do better? Merci!

[jfarcand]

Which version of Wicket/Atmosphere are you using? @papegaaij any idea? From the source code it seems there is an NPE when doing this

@0xabadea It is not an Atmosphere issue, so you may want to file an issue in Wicket as well.

[0xabadea]

I filed https://issues.apache.org/jira/browse/WICKET-4965. Please close this one if the bug is not in Atmosphere.

Out of curiosity, how come it makes sense to invoke resume() on an AtmosphereResource whose handler has been destroyed?

[jfarcand]

@0xabadea The resource may still be available for Broadcaster.