Abstract

Topaz, the experimental computing environment built and used at SRC, is implemented in the Modula-2+ programming language, which provides garbage collection. Garbage collection simplifies the construction of complex systems, and is tied to a number of other Topaz and Modula-2+ features, such as runtime polymorphism, language safety, information-hiding, object cleanup, persistent objects, and network objects. Although there are costs to using garbage collection, these are avoided or tolerated in Topaz. For example, because Topaz must avoid noticeable interruption of service due to garbage collection, it uses a concurrent garbage collector. Measurements show that the use of the REF heap in Topaz is similar in many ways to the use of heaps in Lisp-like environments, but different in others. For example, in typical large Topaz programs, the REF heap contains millions of bytes, with tens of thousands of objects from among hundreds of staticallydeclared types; objects of only a few types pre...

Citations