Connection pool running out of connections in JBoss EAP

Issue

• Unable to get a new connection from a JBoss EAP managed connection pool

• In JBoss EAP 6 and later IJ000453 and IJ000655 messages such as the following appear together in the server.log

  ... javax.resource.ResourceException: IJ000453: Unable to get managed connection for java:jboss/datasources/MyDS
  ...
  ... javax.resource.ResourceException: IJ000655: No managed connections available within configured blocking timeout (30000 [ms])
  

• In JBoss EAP 5 and earlier, messages such as the following appear in the server.log

  ... No ManagedConnections available within configured blocking timeout ( 30000 [ms] ]
  

• Server hangs with many threads blocking with stack traces like the following:

  "ajp-127.0.0.1-8009-1" daemon prio=10 tid=0x00002aaabde44000 nid=0x106c waiting on condition [0x000000004d2b7000]
     java.lang.Thread.State: TIMED_WAITING (parking)
      at sun.misc.Unsafe.park(Native Method)
      - parking to wait for  <0x000000078f4a3140> (a java.util.concurrent.Semaphore$FairSync)
      at java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:196)
      at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireSharedNanos(AbstractQueuedSynchronizer.java:1011)
      at java.util.concurrent.locks.AbstractQueuedSynchronizer.tryAcquireSharedNanos(AbstractQueuedSynchronizer.java:1303)
      at java.util.concurrent.Semaphore.tryAcquire(Semaphore.java:383)
      at org.jboss.resource.connectionmanager.InternalManagedConnectionPool.getConnection(InternalManagedConnectionPool.java:193)
      at org.jboss.resource.connectionmanager.JBossManagedConnectionPool$BasePool.getConnection(JBossManagedConnectionPool.java:747)
      at org.jboss.resource.connectionmanager.BaseConnectionManager2.getManagedConnection(BaseConnectionManager2.java:404)
      at org.jboss.resource.connectionmanager.TxConnectionManager.getManagedConnection(TxConnectionManager.java:424)
      at org.jboss.resource.connectionmanager.BaseConnectionManager2.allocateConnection(BaseConnectionManager2.java:496)
      at org.jboss.resource.connectionmanager.BaseConnectionManager2$ConnectionManagerProxy.allocateConnection(BaseConnectionManager2.java:941)
      at org.jboss.resource.adapter.jdbc.WrapperDataSource.getConnection(WrapperDataSource.java:89)
      ...