TRACKING LARGE NUMBERS OF MOVING OBJECTS IN AN EVENT PROCESSING SYSTEM

• US 20120291049A1
• Filed: 05/13/2011
• Published: 11/15/2012
• Est. Priority Date: 11/18/2010
• Status: Active Grant

• Current Assignee: Oracle International Corporation (Oracle Corporation)
• Original Assignee: Oracle International Corporation (Oracle Corporation)
• Inventors: Park, Hoyong, Hsiao, Eric, Piper, Andrew
• Granted Patent: US 9,189,280 B2
• Time in Patent Office: Days
• US Class Current: 719/318
• CPC Class Codes: G06F 16/2237 Vectors, bitmaps or matrices
• CPC Class Codes: G06F 16/2246 Trees, e.g. B+trees
• CPC Class Codes: G06F 16/2379 Updates performed during online database operations; commit processing
• CPC Class Codes: G06F 9/5027 the resource being a machine, e.g. CPUs, Servers, Terminals
• CPC Class Codes: G06F 9/505 considering the load
• CPC Class Codes: G06F 9/542 Event management; Broadcasting; Multicasting; Notifications

Abstract

Techniques for tracking large numbers of moving objects in an event processing system. In one set of embodiments, an input event stream can be received, where the events in the input event stream represent the movement of a plurality of geometries or objects. The input event stream can then be partitioned among a number of processing nodes of the event processing system, thereby enabling parallel processing of one or more continuous queries for tracking the objects. In a particular embodiment, the partitioning can be performed such that (1) each processing node is configured to track objects in a predefined spatial region, and (2) the spatial regions for at least two nodes overlap. This overlapping window enables a single node to find, e.g., all of the objects within a particular distance of a target object, even if the target object is in the process of moving from the region of that node to the overlapping region of another node.

Claims

1. A method comprising:

receiving, by a computer system, an input event stream comprising a sequence of events, the sequence of events representing the movement of a plurality of objects; and

partitioning, by the computer system, the input event stream among a plurality of processing nodes to facilitate parallel tracking of the objects, wherein each processing node is configured to track objects in a predefined spatial region, and wherein the predefined spatial regions for at least two processing nodes in the plurality of processing nodes overlap.

2. The method of claim 1 wherein each event includes an identifier of an object and a current position of the object.

3. The method of claim 2 wherein partitioning the input event stream comprises, for each event:

determining a subset of processing nodes in the plurality of processing nodes configured to track objects in a predefined spatial region that encompasses the current position of the object; and

for each processing node in the plurality of processing nodes;

determining whether the processing node is in the subset;

if the processing node is in the subset, determining whether to insert or update the event in a relation operated on by the processing node; and

if the processing node is not in the subset, determining whether to delete the event from the relation operated on by the processing node.

4. The method of claim 3 wherein determining whether to insert or update the event in the relation operated on by the processing node comprises:

retrieving, from a bit vector stored for the processing node, a bit value associated with the object;

if the bit value is zero;

transmitting to the processing node a command for inserting the event into the relation; and

setting the bit value to one; and

if the bit value is one, transmitting to the processing node a command for updating the event in the stream.

5. The method of claim 3 wherein determining whether to delete the event from the relation operated on by the processing node comprises:

retrieving, from a bit vector stored for the processing node, a bit value associated with the object; and

if the bit value is one;

transmitting to the processing node a command for deleting the event from the relation; and

clearing the bit value to zero.

6. The method of claim 3 wherein the predefined spatial regions for the plurality of processing nodes are indexed using an R-tree index.

7. The method of claim 6 wherein determining the subset of processing nodes comprises performing, based on the current position of the object, a search into the R-tree index.

8. The method of claim 1 wherein the computer system is a load balancing node of an event processing system.

9. The method of claim 1 wherein the sequence of events represent the movement of more than one million distinct objects.

10. The method of claim 1 wherein the plurality of objects are motor vehicles.

11. The method of claim 1 wherein the predefined spatial regions for the plurality of processing nodes are one-dimensional, two-dimensional, or three-dimensional regions.

12. A non-transitory computer readable medium having stored thereon program code executable by a processor, the program code comprising:

code that causes the processor to receive an input event stream comprising a sequence of events, the sequence of events representing the movement of a plurality of objects; and

code that causes the processor to partition the input event stream among a plurality of processing nodes to facilitate parallel tracking of the objects, wherein each processing node is configured to track objects in a predefined spatial region, and wherein the predefined spatial regions for at least two processing nodes in the plurality of processing nodes overlap.

13. The non-transitory computer readable medium of claim 12 wherein each event includes an identifier of an object and a current position of the object.

14. The non-transitory computer readable medium of claim 13 wherein partitioning the input event stream comprises, for each event:

determining a subset of processing nodes in the plurality of processing nodes configured to track objects in a predefined spatial region that encompasses the current position of the object; and

for each processing node in the plurality of processing nodes;

determining whether the processing node is in the subset;

if the processing node is in the subset, determining whether to insert or update the event in a relation operated on by the processing node; and

if the processing node is not in the subset, determining whether to delete the event from the relation operated on by the processing node.

15. An event processing system comprising:

a load balancer node; and

a plurality of processing nodes,

wherein the load balancer node is configured to;

receive an input event stream comprising a sequence of events, the sequence of events representing the movement of a plurality of objects; and

partition the input event stream among the plurality of processing nodes to facilitate parallel tracking of the objects, wherein each processing node is configured to track objects in a predefined spatial region, and wherein the predefined spatial regions for at least two processing nodes in the plurality of processing nodes overlap.

16. The event processing system of claim 15 wherein each event includes an identifier of an object and a current position of the object.

17. The event processing system of claim 16 wherein partitioning the input event stream comprises, for each event:

determining a subset of processing nodes in the plurality of processing nodes configured to track objects in a predefined spatial region that encompasses the current position of the object; and

for each processing node in the plurality of processing nodes;

determining whether the processing node is in the subset;

if the processing node is in the subset, determining whether to insert or update the event in a relation operated on by the processing node; and

if the processing node is not in the subset, determining whether to delete the event from the relation operated on by the processing node.

18. The event processing system of claim 15 wherein the load balancer node and the plurality of processing nodes corresponding to separate processors of a single computer system.

19. The event processing system of claim 15 wherein the load balancer node and the plurality of processing nodes correspond to separate computer systems.