The distributed garbage collection function is used to remove distributed objects that are no longer referenced by any object space. Distributed garbage collection performs the same role as the base Smalltalk garbage collection function, with the exception that cycles are not collected. For example; object x, in object space A, references object y, in object space B, and vice versa. Even with no other references, since the objects form a distributed cycle, they will not be collected. Users are required to break such cycles.

SST provides distributed garbage collection equivalent to the function provided in the Distributed feature. There are, however, differences in the setup procedures. The Distributed feature distributed garbage collector is started automatically in each object space. In SST, one object space needs to be specified as the coordinator space for the distributed garbage collector. Additionally, each object space must start and shutdown the distributed garbage collector with code similar to the following: