ConcurrentModificationException while inserting bulk vertices, with properties in Titan (0.5.3)

[Huzaifa Arif]

I got the following exception in my logs:

Exception occurred in Groovy : 'java.util.ConcurrentModificationException

                at com.thinkaurelius.titan.graphdb.transaction.addedrelations.SimpleAddedRelations.getView(SimpleAddedRelations.java:35)

                at com.thinkaurelius.titan.graphdb.vertices.StandardVertex.getAddedRelations(StandardVertex.java:66)

                at com.thinkaurelius.titan.graphdb.transaction.StandardTitanTx.setProperty(StandardTitanTx.java:764)

                at com.thinkaurelius.titan.graphdb.vertices.AbstractVertex.setProperty(AbstractVertex.java:244)

                at com.thinkaurelius.titan.graphdb.vertices.AbstractVertex.setProperty(AbstractVertex.java:239)

                at com.tinkerpop.blueprints.util.wrappers.batch.BatchGraph$BatchVertex.setProperty(BatchGraph.java:492)

                at com.tinkerpop.blueprints.util.ElementHelper.setProperties(ElementHelper.java:164)

                at com.tinkerpop.blueprints.util.ElementHelper$setProperties.call(Unknown Source)

                at Script4$_bulkInsertion_closure1.doCall(Script4.groovy:14)

                at Script4.bulkInsertion(Script4.groovy:6)

This occurred while inserting nodes using groovy script in Titan.

I have attached the groovy script.

What can be the cause for this? I have tried adding some nodes and updating removing the same nodes from another thread to reproduce the scenario, but I was not able to.

Also how can I set the Transaction configuration to multi-threaded so that instead of using "SimpleAddedRelations" I can use "ConcurrentAddedRelations" to avoid this scenario.