1. A computer system control method for dynamically changing a configuration of the system by computer processing to be suitable for content of network traffic information, the method comprising the steps of: storing, in advance, a plurality of stream-format resource assignments that indicate tasks and assignment of resources with which the tasks are executed in a stream format so as to be adapted for phase patterns corresponding to a plurality of different contents of the network traffic information, each of said stream-format resource assignments comprising a phase pattern; measuring the network traffic information; selecting a stream-format resource assignment, from the plurality of stored stream-format resource assignments, with a phase pattern that is closest to the measured network traffic information as a next phase; and switching from the stream-format resource assignment in a selected present phase to stream-format resource assignment in the next phase, wherein the switching comprises: initiating a switch from the stream-format resource assignment in the selected present phase to the stream-format resource assignment in the next phase; each resource processes queued tasks of the selected present phase until no tasks of the present phase remain in the resource queue; at least one resource processes at least one alternative task of the next phase; and each resource processes tasks in stream-format resource assignment in the next phase after completing any alternative tasks in the resource queue.