Method and system for reclaiming unreferenced computer memory space
US5321834A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 21, 1993 |
| Grant date | Jun 14, 1994 |
| Priority date | — |
| Expiry date | Oct 21, 2013 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S707/99957
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A computer program is disclosed for reclaiming unreferenced computer memory space, also known as garbage collection. The program operates in a virtual memory environment wherein user memory space is divided into pages. For each active page, a table stores the age of the oldest object on the page (A-value) and the age of the youngest object pointed to from that page (F-value). A generational partition divides the pages into "safe" pages and "threatened" pages, based on their A-values. Rescuer pages, which may contain pointers to threatened pages, are determined by comparing the F-values to the generational partition. All potential pointers on the rescuing pages are traced and the objects pointed to are marked as reachable. All objects reachable from other reachable objects are also marked. Unmarked threatened objects are de-allocated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.