First off, I'm really interested in seeing your book. My own experience with graph theory is limited to the old-school stuff and I would very much like to learn more about how it relates to big data applications.
My question: How do Apache Spark and Neo4j hold up in terms of performance and memory use compared to some of the non-Java/non-JVM API's?
I ask because in the past I've found that graph-related applications require a lot of objects (edges, nodes, etc.) and that the overhead for Java object construction and memory use gets to be a problem. Seeing how successful Apache Spark is, it seems likely that they've addressed the issue. I am curious as to what your experience has been.