In computer science, the Boehm–Demers–Weiser garbage collector, often simply known as Boehm GC, is a conservative garbage collector for C and C++.^[1]

Boehm GC is free software distributed under a permissive free software licence similar to the X11 license.


The developer describes the operation of the collector as follows:

The collector uses a mark-sweep algorithm. It provides incremental and generational collection under operating systems which provide the right kind of virtual memory support. (Currently this includes SunOS[45], IRIX, OSF/1, Linux, and Windows, with varying restrictions.) It allows finalization code to be invoked when an object is collected. It can take advantage of type information to locate pointers if such information is provided, but it is usually used without such information.

http://www.hboehm.info/gc/#details

Boehm GC can also run in leak detection mode^[2] in which memory management is still done manually, but the Boehm GC can check if it is done properly. In this way a programmer can find memory leaks and double deallocations.

Boehm GC is also distributed with a C string handling library called cords. This is similar to ropes in C++ (strings are trees of small arrays, and they never change), but instead of using reference counting for proper deallocation, it relies on garbage collection to free objects. Cords are good at handling very large texts, modifications to them in the middle, slicing, concatenating, and keeping history of changes (undo/redo functionality).