1. A method of assigning a plurality of threads to a plurality of processors, each of the threads being a unit of execution of a real-time operation, the method comprising: selecting a tightly coupled thread group from among the threads based on coupling attribute information indicative of a coupling attribute between the threads, the tightly coupled thread group including a set of tightly coupled threads running in cooperation with each other; and performing a scheduling operation of dispatching the tightly coupled threads to several of the processors that are equal in number to the tightly coupled threads to simultaneously execute the tightly coupled threads by the several of the processors.