1. A method, implemented in a data processing system, of subdividing processing cycles of a thread among a set of threadlets within an application program, comprising: obtaining a first time slice for said thread having a fixed execution time within said data processing system, indicating to said data processing system the beginning and ending of said threadlets in said application program whose processing cycles will be subdivided among said set of threads, loading said data processing system with a threadlet control block of said thread containing said set of threadlets within said application program, and executing said set of threadlets for said threadlet control block in the order specified and within the fixed execution time of said time slice.