A comprehensive evaluation of object scanning techniques

At the heart of all garbage collectors lies the process of identifying and processing reference fields within an object. Despite its key role, and evidence of many different implementation approaches, to our knowledge no comprehensive quantitative study of this design space exists. The lack of such a study means that implementers must rely on ‘conventional wisdom’, hearsay, and their own costly analysis. Starting with mechanisms described in the literature and a variety of permutations of these, we explore the impact of a number of dimensions including: a) the choice of data structure, b) levels of indirection from object to metadata, and c) specialization of scanning code. We perform a comprehensive examination of these tradeoffs on four different architectures using eighteen benchmarks and hardware performance counters. We inform the choice of mechanism with a detailed study of heap composition and object structure as seen by the garbage collector on these benchmarks. Our resul...

• Type: Journal
• Year: 2011
• Where: IWMM
• Authors: Robin Garner, Stephen M. Blackburn, Daniel Frampton
• Keywords: Garbage Collectors, Hardware, Hardware Performance Counters, IWMM 2011, Programming Languages Processors