Patent ID: 9690818
Date: 2017-06-27
CPC Classifications: G06F

Claim:
1. A computer-implemented method for locking retained resources of database information in a distributed shared disk cluster environment comprising a plurality of nodes, the method comprising: receiving a request on demand for physical access to a page by a task of a first node, wherein the request on demand is configured to allow the task to bypass out of order one or more waiting access requests to obtain a physical lock on the page and wherein the request on demand indicates a first lock mode; determining whether a second node holds a lock on the page, the lock having a second lock mode; determining whether the first lock mode and the second lock mode are compatible; sending a demand downgrade request to the second node currently owning the physical lock; determining whether a previous downgrade request has been sent to the second node; determining a status of the previous downgrade request, when a previous downgrade request has been sent; dropping the demand downgrade request when the previous downgrade request is estimated to be completed within a specific future time based, at least in part, on the determined status of the previous downgrade request and the determination of lock mode compatibility; dropping the previous downgrade request when the previous downgrade request is estimated to be completed outside a specific future time based, at least in part, on the determined status of the previous downgrade request and a determination that the first lock mode and the second lock mode are not compatible; and granting the first node physical access to the page, after the second node downgrades the physical lock.