Subtasks may need to migrate from one node to another node due to the data dependency between the subtasks.Subtask migration is accomplished by communicating among the nodes.

• 由于子工作间的资料相依性与工作指派的结果, 导致运算节点上的子工作需进行转移, 然而子工作转移所进行的动作就是运算节点间的资料传递。