Portable, unobtrusive garbage collection for multiprocessor systems

We describe and prove the correctness of a new concurrent mark-and-sweep garbage collection algorithm. This algorithm derives from the classical on-the-fly algorithm from Dijkstra et al. [9]. A distinguishing feature of our algorithm is that it supports multiprocessor environments where the registers of running processes are not readily accessible, without imposing any overhead on the elementary operations of loading a register or reading or initializing a field. Furthermore our collector never blocks running mutator processes except possibly on requests for free memory; in particular, updating a field or creating or marking or sweeping a heap object does not involve system-dependent synchronization primitives such as locks. We also provide support for process creation and deletion, and for managing an extensible heap of variable-sized objects.