Performing exact garbage collection using bitmaps that identify

Details Performing exact garbage collection using bitmaps that identify Performing exact garbage collection using bitmaps that identify

1997-04-23

1999-07-06

Kim, Kenneth S.

Data processing: database and file management or data structures

Database design

Data structure types

707103, 711165, 709303, G06F 1200

Patent

active

059208767

ABSTRACT:
One embodiment of the present invention presents a method and apparatus for efficiently performing garbage collection on objects defined within an object-oriented programming system. Garbage collection typically involves following pointers to determine which objects are presently being referenced so that other objects, that are not being referenced, can be removed. To this end, the present invention maintains a bitmap for each object that indicates which variables in the object are pointer variables and which variables are non-pointer variables. A garbage collection process examines the bitmap, and on the basis of the pattern contained in the bitmap jumps to a particular routine that is tailored to garbage collect the particular pattern of pointer and non-pointer values in the object. Note that the system includes a routine tailored for each possible bitmap pattern. This technique speeds up the garbage collection process by eliminating the need to read type information one variable at a time to determine which variables within an object contain pointers.

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