1. For performing garbage collection, a method comprising: A) providing a computer system that includes memory and executes a mutator that modifies references in a dynamically allocated heap in the memory; B) configuring the computer system to act as a garbage collector that collects respective collection sets in collection increments and that: i) divides at least a portion of the heap into reference stripes and remembered-set regions; ii) maintains for each of the remembered-set regions a remembered set, associated therewith and stored in a plurality of remembered-set structures associated with that remembered-set region and with respective different ones of the reference stripes, by executing, in a plurality of concurrent update threads with each of which the garbage collector associates at any one time a different set of the remembered-set structures, a reference-recording operation in which the threads scan the reference stripes for references and each thread records in only the remembered-set structures of the set thereof currently associated therewith the locations of references thereby found; iii) identifies potentially reachable objects in an operation that includes employing the remembered sets to identify potentially reachable objects in respective remembered-set regions; and iv) reclaims memory occupied by objects not thereby determined to be potentially reachable; and C) employing the computer system to execute the garbage collector.