Parallel Objects Migration: a Fine-Grained Approach to Load Distribution

Migration is a fundamental mechanism for achieving load balancing and locality of references in parallel and distributed applications. This paper presents the migration mechanisms implemented in the Parallel Objects (PO) programming environment, which assumes a fine granularity in allocation and reallocation of objects. In fact, a PO object can dynamically distribute its components onto several nodes depending on its dynamic need for resources, and the migration mechanisms implemented in PO allow object components to migrate independently of each other. This paper describes how the PO environment can exploit the migration mechanisms via an embedded load- balancing policy, possibly driven by user-defined allocation hints, and evaluates the effectiveness of the approach in several application examples