Abstract: A garbage collector that employs the train algorithm identifies popular objects by a count of references to them and places such objects into special, single-object car sections that are normally smaller than the car sections employed for objects that are less popular. When such cars are part of the collection set and evacuated, the evacuation occurs by relinking, without relocating the objects and memory. References to such popular objects therefore do not need to be updated as a result of evacuation. A limit is imposed on the number of entries in the remembered sets used to keep track of references to objects and such popular-object car sections, and any popular-object car section whose remembered set has more than a threshold number of entries is treated as reachable and still popular without having the memory regions that those entries identify searched for valid references.