I am looking for a good Java Graph Library which is thread safe for concurrent access. JGraphT, JUNG, JTS are very good but again for concurrent access I will have to synchronize it externally which is becoming a pain. It is a pain because say If thread A have to access 50 vertices, Thread B for another 50 with the intersection of vertices being 20 vertices. Now while writing code I need to know this 20 before so that I can synchronize it accordingly. Pl suggest if there exists some framework for graphs which has inbuilt support for concurrency
Neo4J.org sits in this space IIRC.