Load balancing algorithm for servicing client requests

• US 20070156869A1
• Filed: 12/30/2005
• Published: 07/05/2007
• Est. Priority Date: 12/30/2005
• Status: Active Grant

• Current Assignee: SAP SE
• Original Assignee: SAP SE
• Inventors: Galchev, Galin, Luik, Oliver, Fleischer, Christian
• Granted Patent: US 8,707,323 B2
• Time in Patent Office: Days
• US Class Current: 709/223
• CPC Class Codes: G06F 9/505 considering the load

Abstract

A connection manager includes a dispatcher that dispatches requests to worker nodes in an application server according to a load balancing algorithm.

Claims

1. An application server comprising:

a connection manager to receive a request associated with an existing distributable session, the connection manager including a dispatcher to send the request to a worker node assigned to handle the session if the worker node is available, the dispatcher to select another worker node to which to send the request according to a load balancing algorithm if the worker node is not available.

2. The application server of claim 1, wherein the worker node is available if there are no active requests for the session that the worker node assigned to handle the session has yet to process.

3. The application server of claim 2, wherein the worker node is available if additionally there are no active request notifications pending in a queue associated with the worker node assigned to handle the session.

4. The application server of claim 1, wherein the worker node is not available if the worker node is busy.

5. The application server of claim 1, wherein the dispatcher to select another worker node to which to send the request comprises the dispatcher to select on a round-robin basis the other worker node from a list of worker nodes maintained in a data structure accessible to the dispatcher.

6. The application server of claim 1, wherein the dispatcher to select another worker node to which to send the request comprises the dispatcher to select on a weighted basis the other worker node from a list of worker nodes maintained in a data structure accessible to the dispatcher.

7. The application server of claim 6, wherein the dispatcher to select the other worker node based on a lowest number of request notifications in a request notification queue associated with the other worker node as compared to a number of request notifications in a respective request notification queue associated with each of the worker nodes in the list.

8. The application server instance of claim 7, wherein the dispatcher to traverse the list of worker nodes and select the first worker node with an empty associated request notification queue.

9. The application server instance of claim 8, wherein if there is a tie among two or more worker nodes in the list based on the number of request notifications in respective request notification queues, the dispatcher to select the worker node that has at least one idle thread.

10. A method comprising:

receiving a request associated with an existing distributable session at a connection manager;

examining at a dispatcher whether a worker node assigned to handle the session is available to process the request;

sending the request from the dispatcher to the assigned worker node if the assigned worker node is available, and

selecting another worker node to which to send the request according to a load balancing algorithm if the assigned worker node is not available.

11. The method of claim 10, further comprising determining the assigned worker node is available if there are no active requests for the session that the assigned worker node has yet to process.

12. The method of claim 11, wherein the assigned worker node is available if there are no active request notifications pending in a queue associated with the assigned worker node.

13. The method of claim 10, wherein selecting another worker node to which to send the request comprises selecting on a round-robin basis the other worker node from a list of worker nodes maintained in a data structure accessible to the dispatcher.

14. The method of claim 10, wherein selecting another worker node to which to send the request comprises selecting on a weighted basis the other worker node from a list of worker nodes maintained in a data structure accessible to the dispatcher.

15. The method of claim 14, wherein selecting the other worker node is based on a lowest number of request notifications in a request notification queue associated with the other worker node as compared to a number of request notifications in a respective request notification queue associated with each of the worker nodes in the list.

16. The method of claim 14, selecting comprises traversing by the dispatcher the list of worker nodes and selecting the first worker node with an empty associated request notification queue.

17. The method of claim 16, wherein if there is a tie among two or more worker nodes in the list based on the number of request notifications in respective request notification queues, selecting the worker node that has at least one idle thread.

18. An article of manufacture, comprising:

fan electronically accessible medium comprising instructions, that when executed by a processor cause the processor to;

receive a request associated with an existing distributable session at a connection manager;

examine at a dispatcher whether a worker node assigned to handle the session is available to process the request;

send the request from the dispatcher to the assigned worker node if the assigned worker node is available, and

select another worker node to which to send the request according to a load balancing algorithm if the assigned worker node is not available.

19. The article of manufacture of claim 18, further comprising instructions that cause the processor to determine the assigned worker node is available if there are no active requests for the session that the assigned worker node has yet to process.

20. The article of manufacture of claim 18, wherein the instructions that cause the processor to select another worker node to which to send the request comprises instructions that cause the processor to select on a weighted basis the other worker node from a list of worker nodes maintained in a data structure accessible to the dispatcher.

21. The article of manufacture of claim 20, wherein the instructions that cause the processor to select the other worker node is based on a lowest number of request notifications in a request notification queue associated with the other worker node as compared to a number of request notifications in a respective request notification queue associated with each of the worker nodes in the list.