Real-time garbage collection in multi-threaded systems on a single processor

We show the difficulties that arise for the implementation of a real-time garbage collector (GC) in a multi-threaded system. A mechanism for synchronization between threads is proposed for a single processor system. It is shown how this mechanism can be used to maintain exact information on roots, to do incremental or even constant-time root-scanning and to allow pre-emption of GC activity.