Published at Onward! 2015. Towards a Dynamic Object Model within Unix Processes Stephen Kell Computer Laboratory, University of Cambridge Cambridge, United Kingdom fi
[email protected] Abstract Historically, the earliest Lisp and Smalltalk virtual ma- Programmers face much complexity from the co-existence chines (VMs) were conceived to eventually supplant Unix- of “native” (Unix-like) and virtual machine (VM) “man- like operating systems. For good or ill, this hasn’t happened: aged” run-time environments. Rather than having VMs re- their descendents today (including Java VMs) nearly al- place Unix processes, we investigate whether it makes sense ways occur within a Unix-like process. Although VMs’ in- for the latter to “become VMs”, by evolving Unix’s user- ternal uniformity can simplify many tasks, interoperating level services to subsume those of VMs. We survey the (little- with the wider world (including other VMs) remains an in- understood) VM-like features in modern Unix, noting com- evitable necessity—yet is a second-class concern to VM mon shortcomings: a lack of semantic metadata (“type in- implementers. The apparent abstraction gap between VMs formation”) and the inability to bind from objects “back” and the Unix “common denominator” leaves a wealth of to their metadata. We describe the design and implementa- programming tasks addressable only by manual or ad-hoc tion of a system, liballocs, which adds these capabilities in means: sharing code via brittle foreign function interfacing, a highly compatible way, and explore its consequences. sharing data (whether in memory or persistently) by manual translation between formats, and making do with a hodge- Categories and Subject Descriptors D.3.4 [Programming podge of per-silo tools for debugging, profiling and the like.