ConflictingModificationAppliedException: Node children was modified by other transaction

In a clustered ODL setup with 3 Controllers and 3 Computes, when we triggered browbeat/rally tests with concurrencies of 8, 16, 32 and times set to 500, we observed the following exception in karaf.

I'm not sure if controller is the right component for this bug, please move it to the appropriate component, thanks.

Note: some related discussion can be found in bug#9038

2017-09-14 15:57:03,143 | ERROR | t-dispatcher-147 | TransactionChainProxy | 211 - org.opendaylight.controller.sal-distributed-datastore - 1.5.2.SNAPSHOT | Tx: member-1-datastore-operational-fe-1-chn-9-txn-1-0 - ready future failed for previous Tx member-1-datastore-operational-fe-1-chn-9-txn-1-0
2017-09-14 15:57:03,143 | WARN | lt-dispatcher-49 | ConcurrentDOMDataBroker | 211 - org.opendaylight.controller.sal-distributed-datastore - 1.5.2.SNAPSHOT | Tx: DOM-CHAIN-8-0 Error during phase CAN_COMMIT, starting Abort
OptimisticLockFailedException

{message=Optimistic lock failed., errorList=[RpcError [message=Optimistic lock failed., severity=ERROR, errorType=APPLICATION, tag=resource-denied, applicationTag=null, info=null, cause=org.opendaylight.yangtools.yang.data.api.schema.tree.ConflictingModificationAppliedException: Node children was modified by other transaction]]}

at org.opendaylight.controller.cluster.datastore.ShardDataTree.lambda$processNextPendingTransaction$0(ShardDataTree.java:751)
at org.opendaylight.controller.cluster.datastore.ShardDataTree.processNextPending(ShardDataTree.java:789)
at org.opendaylight.controller.cluster.datastore.ShardDataTree.processNextPendingTransaction(ShardDataTree.java:736)
at org.opendaylight.controller.cluster.datastore.ShardDataTree.startCanCommit(ShardDataTree.java:819)
at org.opendaylight.controller.cluster.datastore.SimpleShardDataTreeCohort.canCommit(SimpleShardDataTreeCohort.java:90)
at org.opendaylight.controller.cluster.datastore.ChainedCommitCohort.canCommit(ChainedCommitCohort.java:58)
at org.opendaylight.controller.cluster.datastore.CohortEntry.canCommit(CohortEntry.java:97)
at org.opendaylight.controller.cluster.datastore.ShardCommitCoordinator.handleCanCommit(ShardCommitCoordinator.java:236)
at org.opendaylight.controller.cluster.datastore.ShardCommitCoordinator.handleForwardedReadyTransaction(ShardCommitCoordinator.java:114)
at org.opendaylight.controller.cluster.datastore.Shard.handleForwardedReadyTransaction(Shard.java:699)
at org.opendaylight.controller.cluster.datastore.Shard.handleNonRaftCommand(Shard.java:314)
at org.opendaylight.controller.cluster.raft.RaftActor.handleCommand(RaftActor.java:270)
at org.opendaylight.controller.cluster.common.actor.AbstractUntypedPersistentActor.onReceiveCommand(AbstractUntypedPersistentActor.java:44)
at akka.persistence.UntypedPersistentActor.onReceive(PersistentActor.scala:170)
at org.opendaylight.controller.cluster.common.actor.MeteringBehavior.apply(MeteringBehavior.java:104)
at akka.actor.ActorCell$$anonfun$become$1.applyOrElse(ActorCell.scala:544)
at akka.actor.Actor$class.aroundReceive(Actor.scala:502)
at akka.persistence.UntypedPersistentActor.akka$persistence$Eventsourced$$super$aroundReceive(PersistentActor.scala:168)
at akka.persistence.Eventsourced$$anon$1.stateReceive(Eventsourced.scala:727)
at akka.persistence.Eventsourced$class.aroundReceive(Eventsourced.scala:183)
at akka.persistence.UntypedPersistentActor.aroundReceive(PersistentActor.scala:168)
at akka.actor.ActorCell.receiveMessage(ActorCell.scala:526)
at akka.actor.ActorCell.invoke(ActorCell.scala:495)
at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:257)
at akka.dispatch.Mailbox.run(Mailbox.scala:224)
at akka.dispatch.Mailbox.exec(Mailbox.scala:234)
at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
Caused by: org.opendaylight.yangtools.yang.data.api.schema.tree.ConflictingModificationAppliedException: Node children was modified by other transaction
at org.opendaylight.yangtools.yang.data.impl.schema.tree.SchemaAwareApplyOperation.checkConflicting(SchemaAwareApplyOperation.java:78)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.SchemaAwareApplyOperation.checkNotConflicting(SchemaAwareApplyOperation.java:108)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.SchemaAwareApplyOperation.checkWriteApplicable(SchemaAwareApplyOperation.java:170)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.SchemaAwareApplyOperation.checkApplicable(SchemaAwareApplyOperation.java:128)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.AbstractNodeContainerModificationStrategy.checkChildPreconditions(AbstractNodeContainerModificationStrategy.java:305)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.AbstractNodeContainerModificationStrategy.checkMergeApplicable(AbstractNodeContainerModificationStrategy.java:313)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.SchemaAwareApplyOperation.checkApplicable(SchemaAwareApplyOperation.java:131)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.AbstractNodeContainerModificationStrategy.checkChildPreconditions(AbstractNodeContainerModificationStrategy.java:305)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.AbstractNodeContainerModificationStrategy.checkMergeApplicable(AbstractNodeContainerModificationStrategy.java:313)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.SchemaAwareApplyOperation.checkApplicable(SchemaAwareApplyOperation.java:131)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.AbstractNodeContainerModificationStrategy.checkChildPreconditions(AbstractNodeContainerModificationStrategy.java:305)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.AbstractNodeContainerModificationStrategy.checkMergeApplicable(AbstractNodeContainerModificationStrategy.java:313)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.SchemaAwareApplyOperation.checkApplicable(SchemaAwareApplyOperation.java:131)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.AbstractNodeContainerModificationStrategy.checkChildPreconditions(AbstractNodeContainerModificationStrategy.java:305)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.AbstractNodeContainerModificationStrategy.checkTouchApplicable(AbstractNodeContainerModificationStrategy.java:288)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.SchemaAwareApplyOperation.checkApplicable(SchemaAwareApplyOperation.java:125)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.AbstractNodeContainerModificationStrategy.checkChildPreconditions(AbstractNodeContainerModificationStrategy.java:305)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.AbstractNodeContainerModificationStrategy.checkTouchApplicable(AbstractNodeContainerModificationStrategy.java:288)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.SchemaAwareApplyOperation.checkApplicable(SchemaAwareApplyOperation.java:125)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.AbstractNodeContainerModificationStrategy.checkChildPreconditions(AbstractNodeContainerModificationStrategy.java:305)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.AbstractNodeContainerModificationStrategy.checkTouchApplicable(AbstractNodeContainerModificationStrategy.java:288)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.SchemaAwareApplyOperation.checkApplicable(SchemaAwareApplyOperation.java:125)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.StructuralContainerModificationStrategy.checkApplicable(StructuralContainerModificationStrategy.java:99)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.AbstractNodeContainerModificationStrategy.checkChildPreconditions(AbstractNodeContainerModificationStrategy.java:305)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.AbstractNodeContainerModificationStrategy.checkTouchApplicable(AbstractNodeContainerModificationStrategy.java:288)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.SchemaAwareApplyOperation.checkApplicable(SchemaAwareApplyOperation.java:125)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.RootModificationApplyOperation.checkApplicable(RootModificationApplyOperation.java:72)
at org.opendaylight.yangtools.yang.data.impl.schema.tree.AbstractDataTreeTip.validate(AbstractDataTreeTip.java:35)
at org.opendaylight.controller.cluster.datastore.ShardDataTree.lambda$processNextPendingTransaction$0(ShardDataTree.java:743)
... 29 more