METHOD AND SYSTEM FOR SPILLING FROM A QUEUE TO A PERSISTENT STORE

• US 20100223437A1
• Filed: 03/02/2009
• Published: 09/02/2010
• Est. Priority Date: 03/02/2009
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Mishra, Shailendra, Park, Hoyong, Jain, Namit, Srinivasan, Anand
• Granted Patent: US 8,145,859 B2
• Time in Patent Office: Days
• US Class Current: 711/159
• CPC Class Codes: G06F 12/12 Replacement control

Abstract

Techniques for managing memory usage of a processing system by spilling data from a memory to a persistent store based upon an evict policy are provided. A triggering event is detected. In response to the triggering event and based on the evict policy, it is determined whether data from the memory of the processing system is to be spilled to the persistent storage. The determination is made by comparing a level of free memory of the processing system with a threshold specified by the evict policy. The data is evicted from the memory.

Claims

1. A method performed by a data stream processing system for managing memory usage of the processing system, the method comprising:

detecting a triggering event;

responsive to the triggering event, determining, base upon an evict policy, whether data from memory of the processing system is to be spilled to a persistent storage, the determining comprising comparing a level of free memory of the processing system with a threshold specified by the evict policy; and

evicting the data from the memory.

2. The method of claim 1, further comprising:

storing the data to the persistent storage.

3. The method of claim 1, wherein the triggering event is receiving an enqueue request or a dequeue request.

4. The method of claim 1, wherein the memory includes a plurality of buffer queues, further comprising:

determining the threshold from a plurality of thresholds associated with a current state of the processing system based upon the evict policy; and

comparing the threshold with the level of free memory.

5. The method of claim 4, further comprising:

transitioning the processing system from the current state to a new state based upon the comparison.

6. The method of claim 4, wherein the current state of the processing system is associated with a one or more thresholds of the plurality of thresholds.

7. The method of claim 1, wherein the memory includes a plurality of buffer queues, further comprising:

determining a state of the processing system; and

selecting a buffer queue of the plurality of buffer queues from which to perform eviction based upon the evict policy, wherein the data is evicted from the selected buffer queue.

8. The method of claim 1, wherein the evicted data comprises one or more pages of the data stream.

9. The method of claim 1, wherein the eviction of the one or more pages occurs from the largest buffer queue of a plurality of buffer queues in the memory.

10. The method of claim 1, wherein the eviction of the one or more pages occurs from each buffer queue of a plurality of buffer queues in the memory.

11. The method of claim 1, wherein the eviction of the one or more pages is executed by an thread independent from a caller thread.

12. The method of claim 1, wherein prior to eviction, a buffer queue of a plurality of buffer queues operates according to a memory mode where spilling is not performed.

13. A computer-readable storage medium storing a computer program product for managing memory usage of the processing system, the computer program product comprising:

computer code for detecting a triggering event;

computer code for responsive to the triggering event, determining, base upon an evict policy, whether data from memory of the processing system is to be spilled to a persistent storage, the determining comprising comparing a level of free memory of the processing system with a threshold specified by the evict policy; and

computer code for evicting the data from the memory.

14. The computer program product according to claim 13, wherein the triggering event is receiving an enqueue request or a dequeue request.

15. The computer program product according to claim 13, wherein the current state of the processing system is associated with a one or more thresholds of the plurality of thresholds.

16. The computer program product according to claim 13, wherein the memory includes a plurality of buffer queues, the computer program product further comprising:

determining a state of the processing system; and

selecting a buffer queue of the plurality of buffer queues from which to perform eviction based upon the evict policy, wherein the data is evicted from the selected buffer queue.

17. A system for managing memory usage of the processing system, the system including a processor and a memory device including instructions that, when executed by the processor, cause the processor to:

detect a triggering event;

responsive to the triggering event, determine, base upon an evict policy, whether data from memory of the processing system is to be spilled to a persistent storage, the determining comprising comparing a level of free memory of the processing system with a threshold specified by the evict policy; and

evict the data from the memory.

18. The system according to claim 17, wherein the triggering event is receiving an enqueue request or a dequeue request.

19. The system according to claim 17, wherein the current state of the processing system is associated with a one or more thresholds of the plurality of thresholds.

20. The system according to claim 17, wherein the memory includes a plurality of buffer queues, and wherein the instructions, when executed by the processor, further cause the processor to:

determine a state of the processing system; and

select a buffer queue of the plurality of buffer queues from which to perform eviction based upon the evict policy, wherein the data is evicted from the selected buffer queue.