Managing memory comprises execute a mutator comprising a plurality of mutator threads, and concurrently execute a garbage collector. Each of the plurality of mutator threads is separately stopped and notified, and is interrupted at a respective safepoint. In some cases executing the garbage collector includes remapping one or more references to one or more objects in an existing from-space, releasing the existing from-space, relocating one or more live objects that currently reside in a new from-space to one or more corresponding new locations, and identifying a set of one or more candidate pages suitable for forming next from-space during next garbage collection iteration.