High CPU in ScheduledThreadPoolExecutors after they are shutdown

Issue

• We're seeing high CPU in java and it looks like it is caused by ScheduledThreadPoolExecutor that has been shutdown.
• JBoss is running EJB timers that show high CPU persisting in the following calls:

"EJB-Timer-1 [target=jboss.j2ee:ear=myapp.ear,jar=myapp.jar,name=MyEJB,service=EJB3]" prio=10 tid=0x00002aaac0141800 nid=0x3d7 runnable [0x00000000541cc000]
   java.lang.Thread.State: RUNNABLE
    at java.util.concurrent.ScheduledThreadPoolExecutor$DelayedWorkQueue.poll(ScheduledThreadPoolExecutor.java:602)
    at java.util.concurrent.ThreadPoolExecutor.getTask(ThreadPoolExecutor.java:943)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:907)
    at java.lang.Thread.run(Thread.java:662)