My paper, on how to support various concurrency models, with an ownership-based meta-object protocol (MOP) was accepted at TOOLS’12. Below, you will find a preprint version of the paper. A later post will provide details on how to use it and how to experiment with the MOP in Pharo 1.3.


Supporting all known abstractions for concurrent and parallel programming in a virtual machines (VM) is a futile undertaking, but it is required to give programmers appropriate tools and performance. Instead of supporting all abstractions directly, VMs need a unifying mechanism similar to INVOKEDYNAMIC for JVMs.

Our survey of parallel and concurrent programming concepts identifies concurrency abstractions as the ones benefiting most from support in a VM. Currently, their semantics is often weakened, reducing their engineering benefits. They require a mechanism to define flexible language guarantees.

Based on this survey, we define an ownership-based meta-object protocol as candidate for VM support. We demonstrate its expressiveness by implementing actor semantics, software transactional memory, agents, CSP, and active objects. While the performance of our prototype confirms the need for VM support, it also shows that the chosen mechanism is appropriate to express a wide range of concurrency abstractions in a unified way.

  • Identifying A Unifying Mechanism for the Implementation of Concurrency Abstractions on Multi-Language Virtual Machines, Stefan Marr, Theo D’Hondt; Objects, Models, Components, Patterns, 50th International Conference, TOOLS 2012, Prague, Czech Republic, May 28 – June 1, 2012. Proceedings.
  • Paper: PDF
    ©Springer, 2012. The original publication will be made available at
  • BibTex: BibSonomy