Techniques for granting shared locks more efficiently

Details Techniques for granting shared locks more efficiently Techniques for granting shared locks more efficiently

2005-11-15

2005-11-15

Pham, Khanh (Department: 2167)

Data processing: database and file management or data structures

Database design

Data structure types

C707S793000, C707S793000, C710S200000, C711S150000, C711S151000, C711S152000

Reexamination Certificate

active

06965893

ABSTRACT:
Techniques are disclosed for managing resources that are accessible to a plurality of entities. In one embodiment, shared locks on a resource are granted more efficiently by maintaining data that is local to (e.g. on the same node as) each entity to indicate whether an exclusive lock has been granted on the resource to any entity of the plurality of entities. Data that (15) is maintained local to an entity, and that (16) indicates whether any entity has an exclusive lock on a particular resource is referred to herein as a “local exclusive lock flag” for that particular resource. When an entity of the plurality of entities seeks to acquire a shared lock for a particular resource, that entity checks the local exclusive lock flag for that particular resource. If the local exclusive lock flag indicates that no entity holds an exclusive lock on the resource, then the entity seeking the shared lock acquires the shared lock without first receiving a lock grant from the resource manager that manages the resource. In many cases, the resource manager that manages the resource is remotely located relative to the entity that desires the shared lock. Because the local exclusive lock flag is local, the act of checking it does not incur the overhead associated with communicating with a remotely located resource manager. Thus, obtaining a shared lock based on the state of a local exclusive lock flag significantly increases the efficiency of managing access to the resource, particularly for resources for which entities do not frequently require exclusive access.

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