Is com.tinkerpop.blueprints.Graph object thread-safe?

I've a use case where I build a graph from data retrieved from multiple data stores. Each of those data stores has its own client library that builds the sub-graph representing that particular data stores data.

Current implementation Since, I didn't have any concurrency requirements, I build a single Graph object in the service layer and pass it to each of those client libraries and they will use the same Graph instance

New implementation - to meet the SLA

To meet the SLA, i want to pull the data from these data stores concurrently.

1. In this scenario, can each of the client libraries build the sub-graph using the same Graph instance passed from the service layer?
2. Or is there a better way to handle this?

EDIT

How the object being used

1. Client sends a REST request to pull person data
2. Person data is stored in 3 different data stores
3. Service layer creates an instance of com.tinkerpop.blueprints.impls.tg.TinkerGraph and shares it among 3 different threads retreiving the data from 3 different store simultaneously on 3 different threads. Each thread also responsible for adding the data pulled to the shared Graph instance.

It depends on the Graph interface implementation. For example, if you are using TinkerGraph it makes no guarantees of thread-safety. Neo4jGraph uses a ThreadLocal variable to manage transactions which means that you can share the same Neo4jGraph instance with multiple threads without any trouble. Blueprints also allows for multi-threaded transactions via ThreadedTransactionalGraph:

https://github.com/tinkerpop/blueprints/wiki/Graph-Transactions#threadedtransactionalgraph-and-multi-threads-for-one-transaction

but you have to find a Graph that supports that function.