1. A method for identifying connected nodes in a graph, the method comprising: in parallel, selecting an unvisited node of the graph as a root node; searching for nodes that are connected to the root node; when an unvisited connected node is found, indicating that the found node is connected to the root node; when a visited connected node is found, when the found node is indicated as connected to a different root node, indicating a mapping between the root node and the different root node wherein each root node identifies a subgraph of connected nodes and the mappings indicate subgraphs that are connected.