1. A data processing system using a plurality of OSs and a plurality of processors, comprising: a database in which correspondences between tasks processed under the control of the OSs and their attached OSs are defined over the OSs; and management programs operated every said OS, wherein when a startup of the task is requested, the processor that executes one management program retrieves database entries corresponding to the task from the database, wherein when an attached OS of the database entry selected by the retrieval is an attached OS of the one management program, the processor processes the task under the control of the corresponding attached OS, and wherein when the attached OS of the selected database entry is an attached OS of another management program, the processor passes necessary information to a processor that executes said another management program and processes the task under the control of the attached OS of said another management program.