As found in see NETVIRT-883 attachment, there are many thousands of (write only) transactions that are opened in elan manager workss which are apparently never closed:
org.opendaylight.netvirt.elan.internal.ElanInterfaceManager.removeElanInterface(ElanInterfaceManager.java:219)
org.opendaylight.netvirt.elan.internal.InterfaceRemoveWorkerOnElan.call(InterfaceRemoveWorkerOnElan.java:55)
org.opendaylight.netvirt.elan.internal.InterfaceRemoveWorkerOnElan.call(InterfaceRemoveWorkerOnElan.java:21)
org.opendaylight.genius.datastoreutils.DataStoreJobCoordinator$MainTask.run(DataStoreJobCoordinator.java:285)