Multiple threads blocking waiting to close Pipe.in during smoke tests

I'm seeing hangs in the smoke tests where threads are all blocking in the management request handling code. Thread dump attached.

One thing that stands out is the large number of threads in this state:

"pool-1-thread-7" prio=5 tid=102be5800 nid=0x10f377000 in Object.wait() [10f376000]
java.lang.Thread.State: WAITING (on object monitor)
at java.lang.Object.wait(Native Method)

• waiting on <7f5235be8> (a java.lang.Object)
  at java.lang.Object.wait(Object.java:485)
  at org.jboss.as.protocol.Pipe$1.read(Pipe.java:75)
• locked <7f5235be8> (a java.lang.Object)
  at org.jboss.as.protocol.ConnectionImpl$MessageInputStream.close(ConnectionImpl.java:302)
  at org.jboss.as.protocol.StreamUtils.safeClose(StreamUtils.java:294)
  at org.jboss.as.protocol.mgmt.AbstractMessageHandler.handleMessage(AbstractMessageHandler.java:65)
  at org.jboss.as.protocol.ConnectionImpl.safeHandleMessage(ConnectionImpl.java:254)
  at org.jboss.as.protocol.ConnectionImpl$1$1.run(ConnectionImpl.java:213)
  at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
  at java.lang.Thread.run(Thread.java:680)

I don't see how there would be that many concurrent requests going on; what I suspect is happening is those threads are handling requests from different test cases and are hanging. Eventually the pool is exhausted.