Multilevel locking system and method
US5161227A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 13, 1989 |
| Grant date | Nov 3, 1992 |
| Priority date | — |
| Expiry date | Nov 13, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F16/2343
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A multi-processor computer system in which each processor is under the control of separate system software and access a common database. A two level lock management system is used to prevent data corruption due to unsychronized data access by the multiple processors. By this system, subsets of data in the database are assigned respectively different lock entities. Before a task running on one of the processors access data in the database it first requests permission to access the data in a given mode with reference to the appropriate lock entity. A first level lock manager handles these requests synchronously, using a simplified model of the locking system having shared and exclusive lock modes to either grant or deny the request. All requests are then forwarded to a second level lock manager which grants or denies the request based on a more robust model of the locking system and queues denied requests. The denied requests are granted, in turn, as the tasks which have been granted access finish processing data in the database.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.