node_split(nodes, partition_book=None, rank=None, force_even=True)¶
Split nodes and return a subset for the local rank.
This function splits the input nodes based on the partition book and returns a subset of nodes for the local rank. This method is used for dividing workloads for distributed training.
The input nodes are stored as a vector of masks. The length of the vector is the same as the number of nodes in a graph; 1 indicates that the vertex in the corresponding location exists.
There are two strategies to split the nodes. By default, it splits the nodes in a way to maximize data locality. That is, all nodes that belong to a process are returned. If force_even is set to true, the nodes are split evenly so that each process gets almost the same number of nodes.
When force_even is True, the data locality is still preserved if a graph is partitioned with Metis and the node/edge IDs are shuffled. In this case, majority of the nodes returned for a process are the ones that belong to the process. If node/edge IDs are not shuffled, data locality is not guaranteed.
The vector of node Ids that belong to the rank.
- Return type