Description of problem:
When attempting to shutdown a JBoss ON agent, the agent takes a long while to actually shutdown. When it finally shuts-down it is due to the process being killed.

Version-Release number of selected component (if applicable):
4.7.0.JON [adad71f]

How reproducible:
Always

Steps to Reproduce:
1.  Start JBoss ON system:

        ./rhqctl start

2.  After system is up and running, shutdown system:

        ./rhqctl stop

Actual results:
Agent takes a couple minutes to actually stop and the log contains the following message repeated every few seconds:

2013-09-18 14:35:47,766 DEBUG [Thread-6] (org.rhq.enterprise.agent.AgentShutdownHook)- {AgentShutdownHook.thread-is-still-active}Thread [pool-3-thread-1] is still alive - its stack trace follows:
java.lang.Throwable: Thread [pool-3-thread-1]
	at sun.misc.Unsafe.park(Native Method)
	at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:226)
	at java.util.concurrent.locks.AbstractQueuedSynchronizer$ConditionObject.awaitNanos(AbstractQueuedSynchronizer.java:2081)
	at java.util.concurrent.DelayQueue.take(DelayQueue.java:193)
	at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:688)
	at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.take(ScheduledThreadPoolExecutor.java:681)
	at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:1043)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1103)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
	at java.lang.Thread.run(Thread.java:636)

2013-09-18 14:35:47,767 INFO  [Thread-6] (org.rhq.enterprise.agent.AgentShutdownHook)- {AgentShutdownHook.wait}The agent will wait for [1] threads to die

Finally followed by:

2013-09-18 14:36:17,774 INFO  [Thread-6] (org.rhq.enterprise.agent.AgentShutdownHook)- {AgentShutdownHook.no-more-wait}[1] threads are not dying - agent will not wait anymore
2013-09-18 14:36:17,774 INFO  [Thread-6] (org.rhq.enterprise.agent.AgentShutdownHook)- {AgentShutdownHook.threads-still-alive}There are still [1] threads left - the kill thread will
exit the VM shortly if these threads do not die 
2013-09-18 14:36:17,774 INFO  [Thread-6] (org.rhq.enterprise.agent.AgentShutdownHook)- {AgentShutdownHook.exit.shutdown-complete}Shutdown complete - agent will now exit.


Expected results:
Agent should shutdown right away and not be forcefully killed.