ELMO: Extending (Sequential) Languages with Migratable Objects - Compiler Support

Efficient task migration is an important feature in parallel and distributed programs, in particular to support checkpointing and recovery for fault tolerance. It is also very useful in distributed environments like networks of workstations where external loads are often unpredictable and dynamic in nature. We propose simple language extensions (ELMO) to existing sequential programming languages like C, Fortran or C++, that provide a object-based task-parallel execution model. Tasks may be dynamically created, are location transparent, and may be migrated or checkpointed transparently by the system. In this paper, ELMO's language features together with the requisite compiler support is presented. 1 Introduction Networks of workstations present some important problems that need to be addressed before they can be used effectively as a parallel computer. (a) Since local-area networks are not explicitly designed for parallel computing, such systems exhibit high communication latencies wh..