At shutdown you get an warning:
+++
21:37:37,537 WARN [org.jboss.modcluster.advertise.impl.AdvertiseListenerImpl] (MSC service thread 1-1) Failed to interrupt socket reception: java.io.IOException: Invalid argument
at java.net.PlainDatagramSocketImpl.send(Native Method) [:1.6.0_22]
at java.net.DatagramSocket.send(DatagramSocket.java:629) [:1.6.0_22]
at org.jboss.modcluster.advertise.impl.AdvertiseListenerImpl.interruptDatagramReader(AdvertiseListenerImpl.java:240)
at org.jboss.modcluster.advertise.impl.AdvertiseListenerImpl.stop(AdvertiseListenerImpl.java:262)
at org.jboss.modcluster.advertise.impl.AdvertiseListenerImpl.destroy(AdvertiseListenerImpl.java:278)
at org.jboss.modcluster.ModClusterService.shutdown(ModClusterService.java:214)
at org.jboss.modcluster.catalina.CatalinaEventHandlerAdapter.destroy(CatalinaEventHandlerAdapter.java:374)
at org.jboss.modcluster.catalina.CatalinaEventHandlerAdapter.stop(CatalinaEventHandlerAdapter.java:144)
at org.jboss.as.modcluster.ModClusterService.stop(ModClusterService.java:236)
at org.jboss.msc.service.ServiceControllerImpl$StopTask.run(ServiceControllerImpl.java:1819)
at org.jboss.msc.service.ServiceControllerImpl$ClearTCCLTask.run(ServiceControllerImpl.java:2302)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) [:1.6.0_22]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) [:1.6.0_22]
at java.lang.Thread.run(Thread.java:679) [:1.6.0_22]
+++
In fact that should be a debug... And the fix should go in mod_cluster.