METHOD AND SYSTEM FOR REDUCING LOCK OCCURRENCES IN SERVER/DATABASE SYSTEMS

• US 20140122453A1
• Filed: 08/12/2013
• Published: 05/01/2014
• Est. Priority Date: 10/30/2012
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Gocek, Pawel, Malecki, Bartlomiej T., Lech, Grzegorz K., Marszalek, Jan, Wawrzyczek, Joanna
• Granted Patent: US 9,244,966 B2
• Time in Patent Office: Days
• US Class Current: 707/704
• CPC Class Codes: G06F 16/1767 Concurrency control, e.g. optimistic or pessimistic approaches
• CPC Class Codes: G06F 16/21 Design, administration or maintenance of databases
• CPC Class Codes: G06F 16/217 Database tuning G06F16/2282 takes precedence; database performance monitoring G06F11/3409
• CPC Class Codes: G06F 16/2336 Pessimistic concurrency control approaches, e.g. locking or multiple versions without time stamps
• CPC Class Codes: G06F 16/2343 Locking methods, e.g. distributed locking or locking implementation details
• CPC Class Codes: G06F 16/2365 Ensuring data consistency and integrity
• CPC Class Codes: G06F 16/285 Clustering or classification
• CPC Class Codes: G06F 16/955 using information identifiers, e.g. uniform resource locators [URL]
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms

Abstract

The invention relates to a computer-implemented method for limiting the number of concurrent requests in a database system including the following steps: arranging requests to be handled by the database system in at least one queue; defining a maximum value (SS) of concurrent requests corresponding to the at least one queue; monitoring at least one queue utilization parameter corresponding to the at least one queue and calculating a performance value based on the at least one queue utilization parameter, adapting the maximum value (SS) of concurrent requests of the at least one queue dynamically based on the performance value (PF) in order to improve system performance and limiting the number of concurrent requests of the at least one queue dynamically based on the dynamically adapted maximum value (SS).

Claims

1. A computer-implemented method for limiting the number of concurrent requests in a database system comprising the following steps:

arranging requests to be handled by the database system in at least one queue;

defining a maximum value (SS) of concurrent requests corresponding to the at least one queue;

monitoring at least one queue utilization parameter corresponding to the at least one queue and calculating a performance value (PF) based on the at least one queue utilization parameter,

adapting the maximum value (SS) of concurrent requests of the at least one queue dynamically based on the performance value (PF) in order to improve system performance and

limiting the number of concurrent requests of the at least one queue dynamically based on the dynamically adapted maximum value (SS).

2. The method of claim 1, wherein the requests are grouped in at least two groups, wherein each group is associated with a dedicated queue and a queue-specific maximum value (SS) of concurrent requests.

3. The method of claim 2, wherein a request is assigned to a group based on the likelihood of locking of the request with other requests contained in the group, based on the origin of the request or based on the service type of the request.

4. The method of claim 2, wherein a learning mechanism is implemented to derive information about the cause of an exception and to distribute the requests among the at least two groups based on the derived information.

5. The method of claim 1, wherein the number of concurrent requests is limited by rejecting incoming requests before insertion in the queue and/or by removing requests out of the queue.

6. The method of claim 1, wherein the performance value (PF) is calculated for a first period of time (MP(act)−

Δ

MP), wherein the performance value (PF) of the first period of time (MP(act)−

Δ

MP) is used to adapt the maximum value (SS) of concurrent requests in a second period of time (MP(act)), which immediately follows after the first period of time (MP(act)−

Δ

MP).

7. The method of claim 1, wherein the maximum value (SS) of concurrent requests is chosen to maximize the product of number of concurrent requests and average processing time of requests (APT).

8. The method of claim 1, wherein the maximum length (QS) of the at least one queue is adapted dynamically based on the maximum value (SS) of concurrent requests, the queue utilization parameter and a timeout value.

9. The method of claim 1, wherein after receiving a lock time-out of the database the maximum value (SS) of concurrent requests and the maximum length (QS) of the at least one queue is decreased in order to avoid further lock time-outs.

15. The computer program product of claim 1, wherein the requests are grouped in at least two groups, wherein each group is associated with a dedicated queue and a queue-specific maximum value (SS) of concurrent requests.

16. The computer program product of claim 15, wherein a request is assigned to a group based on the likelihood of locking of the request with other requests contained in the group, based on the origin of the request or based on the service type of the request.

17. The computer program product of claim 15, wherein a learning mechanism is implemented to derive information about the cause of an exception and to distribute the requests among the at least two groups based on the derived information.

10. A computer-based database system comprising at least one server acting as a database client comprising:

a dispatcher unit adapted to arrange requests to be handled by the database in at least one queue;

a monitoring unit adapted to

define a maximum value (SS) of requests corresponding to the at least one queue to be processed concurrently,

monitor at least one queue utilization parameter corresponding to the at least one queue and to calculate a performance value (PF) based on the at least one queue utilization parameter,

adjust the maximum value (SS) of concurrent requests of the at least one queue dynamically based on the performance value (PF) in order to improve system performance; and

a limiting unit adapted to limit the number of concurrent requests of the at least one queue dynamically based on the dynamically adapted maximum value (SS).

11. The computer-based system according to claim 10, wherein the dispatcher unit is adapted to group the requests in at least two groups, wherein each group is associated with a dedicated queue and a queue-specific maximum value (SS) of concurrent requests.

12. The computer-based system according to claim 11, wherein the dispatcher unit is adapted to assign a request to a group based on the likelihood of locking of the request with other requests contained in the group, based on the origin of the request or based on the service type of the request.

13. The computer-based system according to claim 10, wherein the system is adapted to limit the number of concurrent requests by rejecting incoming requests before insertion in the queue and/or by removing requests out of the queue.

14. A computer program product for limiting the number of concurrent requests in a database system, the computer program product comprising a computer readable storage medium having program code embodied therewith, the program code readable by a computer to perform a method comprising:

arranging, by a computer, requests to be handled by the database system in at least one queue;

defining, by a computer, a maximum value (SS) of concurrent requests corresponding to the at least one queue;

monitoring, by a computer, at least one queue utilization parameter corresponding to the at least one queue and calculating a performance value (PF) based on the at least one queue utilization parameter,

adapting, by a computer, the maximum value (SS) of concurrent requests of the at least one queue dynamically based on the performance value (PF) in order to improve system performance and

limiting, by a computer, the number of concurrent requests of the at least one queue dynamically based on the dynamically adapted maximum value (SS).

18. The computer program product of claim 14, wherein the number of concurrent requests is limited by rejecting incoming requests before insertion in the queue and/or by removing requests out of the queue.

19. The computer program product of claim 14, wherein the performance value (PF) is calculated for a first period of time (MP(act)−

Δ

MP), wherein the performance value (PF) of the first period of time (MP(act)−

Δ

MP) is used to adapt the maximum value (SS) of concurrent requests in a second period of time (MP(act)), which immediately follows after the first period of time (MP(act)−

Δ

MP).

20. The computer program product of claim 14, wherein the maximum value (SS) of concurrent requests is chosen to maximize the product of number of concurrent requests and average processing time of requests (APT).