LOCK MANAGER ON DISK

• US 20110106778A1
• Filed: 11/05/2009
• Published: 05/05/2011
• Est. Priority Date: 11/05/2009
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Chan, Wilson Wai Shun, Pruscino, Angelo
• Granted Patent: US 8,510,334 B2
• Time in Patent Office: Days
• US Class Current: 707/704
• CPC Class Codes: G06F 16/2343 Locking methods, e.g. distributed locking or locking implementation details

Abstract

A method and apparatus for managing shared resources in a clustered database management system is provided. In an embodiment, multiple master nodes exist in a database management system. A master node receives a lock request from a second node. The lock request is a request for a lock on a shared resource. The master node grants the lock request to the second node. While the second node holds the lock, the second node causes the master node to modify the shared resource.

Claims

1. A computer-implemented method of managing resources in a database management system, comprising:

receiving, at a first master node of a plurality of master nodes, a first lock request from a second node, wherein the first lock request is a request for a lock on a first shared resource;

the first master node granting the lock to the second node;

while said second node holds said lock, said second node causing said first node to modify said first shared resource.

2. The method of claim 1, further comprising:

receiving, at the first master node, a second lock request from a third node, wherein the second lock request is a request for a lock on a second shared resource;

receiving a first modify request from the second node, wherein the first modify request is a request to modify the first shared resource;

subsequent to receiving the first modify request, receiving a second modify request from the third node, wherein the second modify request is a request to modify the second shared resource;

modifying the second shared resource before modifying the first shared resource.

3. The method of claim 2, wherein each modify request comprises an expected completion time.

4. The method of claim 2, further comprising:

based at least in part on a prioritization scheme, determining which modify request should be honored first.

5. The method of claim 4, wherein the prioritization scheme is based on one or more of:

a) an expected completion time associated with the request;

b) priority attributes associated with the request type;

or c) network or system state.

6. The method of claim 1, further comprising:

receiving a second modify request from a second node, wherein the second modify request is a request to modify the first shared resource;

subsequent to receiving the second modify request, receiving a first recall request from the second node, wherein the first recall request causes the first node to refrain from modifying the second shared resource.

7. The method of claim 1, further comprising:

caching said first shared resource at the first master node;

receiving a second modify request from a second node, wherein the second modify request is a request to modify the first shared resource;

modifying the cached copy of the shared resource.

8. The method of claim 1, further comprising:

the first master node assuming mastership over the first shared resource, wherein the first shared resource was previously managed by a third master node of the plurality of master nodes.

9. The method of claim 8, wherein the step of the first master node assuming mastership over the first shared resource is performed in response to the state of the third master node.

10. A computer-implemented method of managing resources in a database management system, comprising:

receiving, at a first master node of a plurality of master nodes, a first request from a second node, wherein the first request is a request for a lock on a shared resource;

the first master node granting the lock to the second node;

the second node generating an in-memory copy of said shared resource;

while said second node holds said lock, said second node causing said first node to modify said shared resource on disk.

11. A computer-readable storage medium storing instructions which, when executed, cause one or more processors to perform the steps of:

receiving, at a first master node of a plurality of master nodes, a first lock request from a second node, wherein the first lock request is a request for a lock on a first shared resource;

the first master node granting the lock to the second node;

while said second node holds said lock, said second node causing said first node to modify said first shared resource.

12. The computer-readable storage medium of claim 11, wherein the instructions further include instructions for:

receiving, at the first master node, a second lock request from a third node, wherein the second lock request is a request for a lock on a second shared resource;

receiving a first modify request from the second node, wherein the first modify request is a request to modify the first shared resource;

subsequent to receiving the first modify request, receiving a second modify request from the third node, wherein the second modify request is a request to modify the second shared resource;

modifying the second shared resource before modifying the first shared resource.

13. The computer-readable storage medium of claim 12, wherein each modify request comprises an expected completion time.

14. The computer-readable storage medium of claim 12, wherein the instructions further include instructions for:

based at least in part on a prioritization scheme, determining which modify request should be honored first.

15. The computer-readable storage medium of claim 14, wherein the prioritization scheme is based on one or more of:

a) an expected completion time associated with the request;

b) priority attributes associated with the request type;

or c) network or system state.

16. The computer-readable storage medium of claim 11, wherein the instructions further include instructions for:

receiving a second modify request from a second node, wherein the second modify request is a request to modify the first shared resource;

subsequent to receiving the second modify request, receiving a first recall request from the second node, wherein the first recall request causes the first node to refrain from modifying the second shared resource.

17. The computer-readable storage medium of claim 11, wherein the instructions further include instructions for:

caching said first shared resource at the first master node;

receiving a second modify request from a second node, wherein the second modify request is a request to modify the first shared resource;

modifying the cached copy of the shared resource.

18. The computer-readable storage medium of claim 11, wherein the instructions further include instructions for:

the first master node assuming mastership over the first shared resource, wherein the first shared resource was previously managed by a third master node of the plurality of master nodes.

19. The computer-readable storage medium of claim 18, wherein the step of the first master node assuming mastership over the first shared resource is performed in response to the state of the third master node.

20. A computer-readable storage medium storing instructions which, when executed, cause one or more processors to perform the steps of:

receiving, at a first master node of a plurality of master nodes, a first request from a second node, wherein the first request is a request for a lock on a shared resource;

the first master node granting the lock to the second node;

the second node generating an in-memory copy of said shared resource;

while said second node holds said lock, said second node causing said first node to modify said shared resource on disk.