Before revision:  Extensive experiments verify that our G-thinker algorithm scales perfectly with the number of CPU cores, achieving over 300x speedup when running on a graph with over 1M vertices in a small cluster.
After revision:  Extensive experiments verify that our G-thinker algorithm scales perfectly with the number of CPU cores, achieving over 300x speedup when running on a graph with 3.77M vertices and 16.5M edges in a 16-node cluster.