It's hard to take the article seriously when it has quotes like this: "The hardest part. 2B edges twitter graph is already huge (its edges are 30 GB in CSV !!!)." Who cares how big the graph is in CSV? That's not the representation you operate over in big data. All of this would have easily fit in memory on any reasonable modern system.
Understand me correctly. This is my research project and I only have a laptop, not a server with 256 GB of RAM. I tested my project on a 2B graph with a hard cap of 8–10 GB of RAM. Of course it fits in memory on any modern system with 64–128 GB of RAM. The whole idea was to conduct a stress test and check how my tool works in out-of-core mode, not to prove to anyone that 2 billion edges (30 GB CSV) constitutes "big data".