Ownership and Reference Counting based Garbage Collection in the Actor World

Juliana Franco

Imperial College London


We propose Pony-ORCA, a fully concurrent protocol for garbage collection in the actor paradigm. It allows actors to perform garbage collection concurrently with any number of other actors. It does not require any form of synchronization across actors except those introduced through the actor paradigm, i.e., message send and message receive.

Pony-ORCA is based on ideas from ownership and deferred, distributed, weighted reference counting. It adapts the messaging system of actors to keep the reference count consistent.

We introduce a formal model and describe the invariants on which it relies. We illustrate these invariants through an example and sketch how they are maintained. We show some benchmarks and argue that the protocol can be implemented efficiently.

Joint work with Sylvan Clebsch, Sebastian Blessing and Sophia Drossopoulou.

Thursday, July 2 2015