US 6,715,146 B1 · Efficiently distributing information used for lock management among distributed resource objects using sequence numbers

Abstract

A system for managing locks that give permission to access resources in a computer system is disclosed. The lock management system is distributed and provides deadlock protection. The lock management system is distributed in that information about which locks have been granted for a resource is stored at both a master node and at the nodes on which are located processes that desire to access to the resource. A master resource object located on the master node grants locks to shadow resource objects located on the nodes on which are located the processes that desire to access the resource. Each shadow resource object grants locks on the resource to the processes that are located on the same node as the shadow resource object. According to an aspect of the invention, the master resource object stores data indicating what is knows about a shadow resource object. The master node increments a sequence number when the master resource object changes what is knows about the shadow resource object. The master resource object transmits the sequence number in messages it sends to the shadow resource object. A shadow resource object maintains master knowledge data indicating what the master resource object knows about the shadow resource object. The sequence number is used to determine whether what the master resource object knows about the shadow resource object is current.

Claims15

Dependent claims

A method for allocating a resource in a system that includes a plurality of processes executing on a plurality of nodes, the method comprising the steps of:

causing a process to obtain, prior to accessing the resource in a particular way, a first lock that grants permission for the process to access the resource in the particular way, wherein the process requests the first lock from a shadow resource object located on the same node as the process;
and
causing the shadow resource object to obtain, prior to granting the first lock to the process, a second lock that grants permission for the shadow resource object to grant locks that grant permission for processes to access the resource in the particular way, wherein the shadow resource object requests the second lock from a master resource object stored on a different node than said shadow resource object;
the master resource object maintaining a sequence number for said shadow resource object;
and
incrementing the sequence number when the master resource object changes what it knows about the shadow resource object.

3 more elements

A computer-readable medium carrying one or more sequences of instructions for allocating a resource in a system that includes a plurality of processes executing on a plurality of nodes, wherein execution of the one or more sequences of instructions by one or more processors causes the one or more processors to perform the steps of:

causing a process to obtain, prior to accessing the resource in a particular way, a first lock that grants permission for the process to access the resource in the particular way, wherein the process requests the first lock from a shadow resource object located on the same node as the process;
and
causing the shadow resource object to obtain, prior to granting the first lock to the process, a second lock that grants permission for the shadow resource object to grant locks that grant permission for processes to access the resource in the particular way, wherein the shadow resource object requests the second lock from a master resource object stored on a different node than said shadow resource object;
the master resource object maintaining a sequence number for said shadow resource object;
and
incrementing the sequence number when the master resource object changes what it knows about the shadow resource object.

3 more elements

A computer system, comprising

a plurality of nodes configured to execute a plurality of processes;
a resource;
said computer system configured to perform the steps of:
causing a process to obtain, prior to accessing the resource in a particular way, a first lock that grants permission for the process to access the resource in the particular way, wherein the process requests the first lock from a shadow resource object located on the same node as the process;
and
causing the shadow resource object to obtain, prior to granting the first lock to the process, a second lock that grants permission for the shadow resource object to grant locks that grant permission for processes to access the resource in the particular way, wherein the shadow resource object requests the second lock from a master resource object stored on a different node than said shadow resource object;
the master resource object maintaining a sequence number for said shadow resource object;
and
incrementing the sequence number when the master resource object changes what it knows about the shadow resource object.

6 more elements

Dependencies are inferred from the claim text.

Efficiently distributing information used for lock management among distributed resource objects using sequence numbers

Life of this patent

Efficiently distributing information used for lock management among distributed resource objects using sequence numbers

Life of this patent

Abstract

Claims15