Reducing Object Storage Requirements in a Multi-user Environment

Many Smalltalk implementations store objects in a large file called a virtual image. Each user must have a copy of the virtual image to execute. Since the image can exceed a megabyte in size, considerable disk space is required to support such a system in a multi-user environment. In this paper, a method is described which can reduce storage requirements for systems which use generation scavenging as a memory reclamation technique. This method also improves the performance of the checkpoint operation and offline garbage-collection.