An orchestration language for parallel objects

Abstract

Charm++, a parallel object language based on the idea of virtual processors, has attained significant success in efficient parallelization of applications. Requiring the user to only decompose the computation into a large number of objects ("virtual processors"), Charm++ empowers its intelligent adaptive runtime system to assign and reassign the objects to processors at runtime. This facility is used to optimize execution, including dynamic load balancing. However, in complex applications, Charm++ programs obscure the overall flow of control: one must look at the code of multiple objects to discern how the sets of objects are orchestrated in a given application. In this paper, we present an orchestration notation that allows expression of Charm++ functionality without its fragmented flow of control.

Parallel Languages and Compilers: Perspective From the Titanium Experience

“…Task-parallel systems include the Java thread model as well as languages extended with OpenMP annotation or threading libraries such as POSIX threads [32,53]. Parallel object-oriented languages such as Charm++ and CC++ have a form of task parallelism in which method invocation logically results in the creation of a separate process to run the method body [34,37]. These models allow programmers to express parallelism between arbitrary sequential processes 1 , so they can be used for the most complicated sorts of parallel dependence patterns, but still lack direct user control over parallel resources.…”