Editing Garbage collection (computer science) (section)

=== Real-time systems ===
Incremental, concurrent, and real-time garbage collectors have been developed, for example by [[Henry Baker (computer scientist)|Henry Baker]] and by [[Henry Lieberman]].<ref name="Huelsbergen-Winterbottom_1998"/><ref name="IECC-GC"/><ref name="Lieberman-Hewitt_1983"/>

In Baker's algorithm, the allocation is done in either half of a single region of memory. When it becomes half full, a garbage collection is performed which moves the live objects into the other half and the remaining objects are implicitly deallocated. The running program (the 'mutator') has to check that any object it references is in the correct half, and if not move it across, while a background task is finding all of the objects.<ref name="Baker_1978"/>

[[Tracing garbage collection#Generational GC (ephemeral GC)|Generational garbage collection]] schemes are based on the empirical observation that most objects die young. In generational garbage collection, two or more allocation regions (generations) are kept, which are kept separate based on the object's age. New objects are created in the "young" generation that is regularly collected, and when a generation is full, the objects that are still referenced from older regions are copied into the next oldest generation. Occasionally a full scan is performed.

Some [[high-level language computer architecture]]s include hardware support for real-time garbage collection.

Most implementations of real-time garbage collectors use [[tracing garbage collection#Real-time garbage collection|tracing]].{{Citation needed|date=September 2019}} Such real-time garbage collectors meet [[hard real-time]] constraints when used with a real-time operating system.<ref name="McCloskey_2008"/>