Singleton RuntimeEngine becomes unresponsive in BPM Suite 6

Issue

• business-central REST became unresponsive after transaction timeout. The project is Singleton strategy

15:16:25,359 WARN  [com.arjuna.ats.arjuna] (Transaction Reaper) ARJUNA012117: TransactionReaper::check timeout for TX 0:ffff7f000001:6d911c6a:55f27047:323f in state  RUN
15:16:25,362 WARN  [com.arjuna.ats.arjuna] (Transaction Reaper Worker 0) ARJUNA012095: Abort of action id 0:ffff7f000001:6d911c6a:55f27047:323f invoked while multiple threads active within it.
15:16:25,363 WARN  [com.arjuna.ats.arjuna] (Transaction Reaper Worker 0) ARJUNA012108: CheckedAction::check - atomic action 0:ffff7f000001:6d911c6a:55f27047:323f aborting with 1 threads active!
15:16:25,365 WARN  [com.arjuna.ats.jta] (Transaction Reaper Worker 0) ARJUNA016029: SynchronizationImple.afterCompletion - failed for org.drools.persistence.jta.JtaTransactionSynchronizationAdapter@793eeafa with exception: java.lang.IllegalMonitorStateException
        at java.util.concurrent.locks.ReentrantLock$Sync.tryRelease(ReentrantLock.java:155) [rt.jar:1.7.0_67]
        at java.util.concurrent.locks.AbstractQueuedSynchronizer.release(AbstractQueuedSynchronizer.java:1260) [rt.jar:1.7.0_67]
        at java.util.concurrent.locks.ReentrantLock.unlock(ReentrantLock.java:460) [rt.jar:1.7.0_67]
        at org.drools.persistence.jta.TransactionLockInterceptor$1.afterCompletion(TransactionLockInterceptor.java:99)
        at org.drools.persistence.TransactionSynchronizationContainer.afterCompletion(TransactionSynchronizationContainer.java:33)
        at org.drools.persistence.jta.JtaTransactionSynchronizationAdapter.afterCompletion(JtaTransactionSynchronizationAdapter.java:25)
        at com.arjuna.ats.internal.jta.resources.arjunacore.SynchronizationImple.afterCompletion(SynchronizationImple.java:96) [jbossjts-jacorb-4.17.29.Final-redhat-1.jar:4.17.29.Final-redhat-1]
        at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.afterCompletion(TwoPhaseCoordinator.java:402) [jbossjts-jacorb-4.17.29.Final-redhat-1.jar:4.17.29.Final-redhat-1]
        at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.afterCompletion(TwoPhaseCoordinator.java:334) [jbossjts-jacorb-4.17.29.Final-redhat-1.jar:4.17.29.Final-redhat-1]
        at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.cancel(TwoPhaseCoordinator.java:120) [jbossjts-jacorb-4.17.29.Final-redhat-1.jar:4.17.29.Final-redhat-1]
        at com.arjuna.ats.arjuna.AtomicAction.cancel(AtomicAction.java:215) [jbossjts-jacorb-4.17.29.Final-redhat-1.jar:4.17.29.Final-redhat-1]
        at com.arjuna.ats.arjuna.coordinator.TransactionReaper.doCancellations(TransactionReaper.java:370) [jbossjts-jacorb-4.17.29.Final-redhat-1.jar:4.17.29.Final-redhat-1]
        at com.arjuna.ats.internal.arjuna.coordinator.ReaperWorkerThread.run(ReaperWorkerThread.java:78) [jbossjts-jacorb-4.17.29.Final-redhat-1.jar:4.17.29.Final-redhat-1]

• A jBPM embedded application faced a deadlock and became unresponsive under load. It uses Singleton RuntimeManager.
• Business Central hung after trying to abort processes and we see threads parking in the following point in Thread dumps:

     - parking to wait for <0x00000007280be810> (a java.util.concurrent.locks.ReentrantLock$NonfairSync)      at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175)      at 

(....)
org.drools.core.impl.StatefulKnowledgeSessionImpl.abortProcessInstance(StatefulKnowledgeSessionImpl.java:551)      at org.drools.core.command.runtime.process.AbortProcessInstanceCommand.execute(AbortProcessInstanceCommand.java:55)      at org.drools.core.command.runtime.process.AbortProcessInstanceCommand.execute(AbortProcessInstanceCommand.java:30
(....)