Modularity: AOSD’12 will be in Potsdam at the end of March, and I am looking forward especially to the MISS’12 workshop.

My understanding of the workshop’s format is that its goal is to encourage the participants to actively interact. Far to often, workshops are just a collection of semi-related presentations, without a common problem and without a common goal. I fear a bit, the MISS workshop will have a similar problem. Being part of the program committee, I have seen all the submissions and the author do tend to prefer business as usual over actual position papers. From my perspective, this is really a pity. It is a lost chance to really exchange ideas actively and perhaps start collaborations with interesting people. A technical paper, with a few ideas and a work-in-progress prototype does not qualify as a position paper in my opinion. Usually, that kind of work only encourages discussion between people that have been working on similar things already. But let’s see how it turns out.

Our contribution to the workshop is a little experience report on how concurrency and modularity are related to each other in interpreter implementations. And, to make it short: modularity does matter to manage concurrency invariants, but things like AOP are far less important than some people might hope.


In this paper, we review what we have learned from implementing languages for parallel and concurrent programming, and investigate the role of modularity. To identify the approaches used to facilitate correctness and maintainability, we ask the following questions: What guides modularization? Are informal approaches used to facilitate correctness? Are concurrency concerns modularized? And, where is language support lacking most?

Our subjects are AmbientTalk, SLIP, and the RoarVM. All three evolved over the years, enabling us to look back at specific experiments to understand the impact of concurrency on modularity.

We conclude from our review that concurrency concerns are one of the strongest drivers for the definition of module boundaries. It helps when languages offer sophisticated modularization constructs. However, with respect to concurrency, other language features like single-assignment are of greater importance. Furthermore, tooling that enables remodularization taking concurrency invariants into account would be of great value.

  • Modularity and Conventions for Maintainable Concurrent Language Implementations: A Review of Our Experiences and Practices, Stefan Marr, Jens Nicolay, Tom Van Cutsem, Theo D’Hondt, Proceedings of the 2nd Workshop on Modularity In Systems Software (MISS’2012), ACM (2012), to appear.
  • Paper: PDF
    ©ACM, 2012. This is the author’s version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. To appear.
  • BibTex: BibSonomy