Memory Management/Cooperative GC
Cooperative Collectors 
Cooperative collectors are collectors that require the rest of the system to participate in the collector's operation, such as with reference counting. These collectors spread the bookkeeping effort throughout the system and don't require a separate mark or sweep phase. These separate GC phases often require the rest of the program to come to a complete stop temporarily, which can create intolerable pauses in program operation. Cooperative collectors don't have these pauses.