User input is received specifying components of a graph-based program specification (628). User input is received specifying links, at least some connecting an output port of an upstream component to an input port of a downstream component. The graph-based program specification is processed to identify one or more subsets (630, 631) of the components, including: identifying one or more subset entry points and one or more subset exit points that occur between components in different subsets based at least in part on data processing characteristics of linked components, and forming the subsets based on the identified subset entry points and exit points. A visual representation of the formed subsets is rendered within a user interface. Prepared code is generated for each formed subset that when used for execution by a runtime system causes processing tasks corresponding to the components in each formed subset to be performed.