default: TracingBroker found some not yet (or never..) closed transaction[chain]s!
[NB: If no stack traces are shown below, then enable transaction-debug-context-enabled in mdsaltrace_config.xml]

  DataBroker : newReadOnlyTransaction()
    1x transactions opened here, which are not closed:
      (...)
      org.opendaylight.controller.md.sal.binding.impl.BindingDOMDataBrokerAdapter.newReadOnlyTransaction(BindingDOMDataBrokerAdapter.java:59)
      (...)
      org.opendaylight.openflowplugin.applications.frm.impl.ForwardingRulesManagerImpl.getReadTranaction(ForwardingRulesManagerImpl.java:181)
      org.opendaylight.openflowplugin.applications.frm.impl.FlowNodeReconciliationImpl$ReconciliationTask.call(FlowNodeReconciliationImpl.java:313)
      org.opendaylight.openflowplugin.applications.frm.impl.FlowNodeReconciliationImpl$ReconciliationTask.call(FlowNodeReconciliationImpl.java:300)
      java.util.concurrent.FutureTask.run(FutureTask.java:266)
      java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
      java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
      java.lang.Thread.run(Thread.java:748)

  DataBroker : newWriteOnlyTransaction()
    1796x transactions opened here, which are not closed:
      (...)
      org.opendaylight.controller.md.sal.binding.impl.BindingDOMDataBrokerAdapter.newWriteOnlyTransaction(BindingDOMDataBrokerAdapter.java:69)
      (...)
      org.opendaylight.netvirt.natservice.internal.NatRouterInterfaceListener.add(NatRouterInterfaceListener.java:80)
      org.opendaylight.netvirt.natservice.internal.NatRouterInterfaceListener.add(NatRouterInterfaceListener.java:30)
      org.opendaylight.genius.datastoreutils.AsyncDataTreeChangeListenerBase$DataTreeChangeHandler.run(AsyncDataTreeChangeListenerBase.java:172)
      java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
      java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
      java.lang.Thread.run(Thread.java:748)

  DataBroker : newReadWriteTransaction()
    6x transactions opened here, which are not closed:
      (...)
      org.opendaylight.controller.md.sal.binding.impl.BindingDOMDataBrokerAdapter.newReadWriteTransaction(BindingDOMDataBrokerAdapter.java:64)
      (...)
      org.opendaylight.genius.infra.ManagedNewTransactionRunnerImpl.callWithNewReadWriteTransactionAndSubmit(ManagedNewTransactionRunnerImpl.java:60)
      org.opendaylight.netvirt.fibmanager.VrfEntryListener$CleanupVpnInterfaceWorker.call(VrfEntryListener.java:1295)
      org.opendaylight.netvirt.fibmanager.VrfEntryListener$CleanupVpnInterfaceWorker.call(VrfEntryListener.java:1275)
      org.opendaylight.infrautils.jobcoordinator.internal.JobCoordinatorImpl$MainTask.runWithUncheckedExceptionLogging(JobCoordinatorImpl.java:416)
      org.opendaylight.infrautils.utils.concurrent.LoggingUncaughtThreadDeathContextRunnable.run(LoggingUncaughtThreadDeathContextRunnable.java:60)
      java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1402)
      java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
      java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
      java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
      java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

  DataBroker : createTransactionChain()
    1x TransactionChains opened but not closed here:
      (...)
      org.opendaylight.controller.md.sal.binding.impl.BindingDOMTransactionChainAdapter.<init>(BindingDOMTransactionChainAdapter.java:45)
      org.opendaylight.controller.md.sal.binding.impl.BindingDOMDataBrokerAdapter.createTransactionChain(BindingDOMDataBrokerAdapter.java:74)
      (...)
      org.opendaylight.ovsdb.southbound.transactions.md.TransactionInvokerImpl.resetTransactionQueue(TransactionInvokerImpl.java:138)
      org.opendaylight.ovsdb.southbound.transactions.md.TransactionInvokerImpl.extractResubmitCommands(TransactionInvokerImpl.java:131)
      org.opendaylight.ovsdb.southbound.transactions.md.TransactionInvokerImpl.extractCommands(TransactionInvokerImpl.java:152)
      org.opendaylight.ovsdb.southbound.transactions.md.TransactionInvokerImpl.run(TransactionInvokerImpl.java:83)
      java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
      java.util.concurrent.FutureTask.run(FutureTask.java:266)
      java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
      java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
      java.lang.Thread.run(Thread.java:748)
        TransactionChain@235b10a8 : newReadWriteTransaction()
          1x transactions opened here, which are not closed:
            (...)
            org.opendaylight.controller.md.sal.binding.impl.BindingDOMTransactionChainAdapter.newReadWriteTransaction(BindingDOMTransactionChainAdapter.java:62)
            org.opendaylight.ovsdb.southbound.transactions.md.TransactionInvokerImpl.run(TransactionInvokerImpl.java:92)
            java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
            java.util.concurrent.FutureTask.run(FutureTask.java:266)
            java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
            java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
            java.lang.Thread.run(Thread.java:748)

    1x TransactionChains opened but not closed here:
      (...)
      org.opendaylight.controller.md.sal.binding.impl.BindingDOMTransactionChainAdapter.<init>(BindingDOMTransactionChainAdapter.java:45)
      org.opendaylight.controller.md.sal.binding.impl.BindingDOMDataBrokerAdapter.createTransactionChain(BindingDOMDataBrokerAdapter.java:74)
      (...)
      org.opendaylight.ovsdb.hwvtepsouthbound.transactions.md.TransactionInvokerImpl.<init>(TransactionInvokerImpl.java:61)
      org.opendaylight.ovsdb.hwvtepsouthbound.HwvtepSouthboundProvider.init(HwvtepSouthboundProvider.java:87)
      (...)
      java.util.concurrent.FutureTask.run(FutureTask.java:266)
      (...)
      java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
      java.util.concurrent.FutureTask.run(FutureTask.java:266)
      (...)
      java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
      java.util.concurrent.FutureTask.run(FutureTask.java:266)
      java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
      java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
      java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
      java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
      java.lang.Thread.run(Thread.java:748)

pingpong: No open transactions, great!