Snap http://snap.stanford.edu/snappy/index.html http://snap.stanford.edu/snappy/index.html, this library is also good and lot of work has been and best part is

Snap http://snap.stanford.edu/snappy/index.html http://snap.stanford.edu/snappy/index.html, this library is also good and lot of work has been and best part is this runs in parallel mode.