System and method for scheduling tasks for execution

• US 20070050771A1
• Filed: 08/30/2005
• Published: 03/01/2007
• Est. Priority Date: 08/30/2005
• Status: Active Grant

• Current Assignee: LinkedIn Corporation (Microsoft Corporation)
• Original Assignee: International Business Machines Corporation
• Inventors: Howland, Michael, Howland, Melissa
• Granted Patent: US 7,793,299 B2
• Time in Patent Office: Days
• US Class Current: 718/102
• CPC Class Codes: G06F 9/4825 Interrupt from clock, e.g. time of day
• CPC Class Codes: G06F 9/485 Task life-cycle, e.g. stopping, restarting, resuming execution G06F9/4881 takes precedence
• CPC Class Codes: G06F 9/4881 Scheduling strategies for dispatcher, e.g. round robin, multi-level priority queues

Abstract

A system for scheduling tasks for execution includes a queue of tasks ordered by scheduled time for execution. A timer thread monitors status of tasks in the queue and selectively dispatches tasks. A guard thread monitors status of tasks in the queue and selectively creates timer threads. The guard thread is responsive to a next task in the queue becoming ready for execution while a first timer thread is still processing a prior task to create a new timer thread to dispatch the next task and mark the first timer thread for closure. Thereafter, the first timer thread closes responsive to the prior task completing.

Claims

1. A method for scheduling tasks for execution, comprising:

ordering tasks in a queue;

providing a timer thread for monitoring status of tasks in said queue and for selectively dispatching tasks;

providing a guard thread for monitoring status of tasks in said queue and for selectively creating timer threads;

operating said guard thread responsive to a next task in said queue becoming ready for execution while a first timer thread is still processing a prior task to create a new timer thread for dispatching said next task and marking said first timer thread for closure;

responsive to said prior task completing, closing said first timer thread.

2. The method of claim 1, further comprising:

responsive to said next task in said queue becoming ready for execution subsequent to said prior task completing, operating said first timer thread to dispatch said next task.

3. The method of claim 1, further comprising:

operating said new timer thread to monitor status of tasks in said queue.

4. The method of claim 1, further comprising:

operating said guard task for selectively setting and resetting a boolean value in timer threads, with said boolean value being set in a timer thread and said boolean value being reset to mark a prior timer thread for closure.

5. The method of claim 4, further comprising:

operating said guard thread to monitor status of tasks in said queue only while said first timer thread is processing a task.

6. The method of claim 1, further comprising:

responsive to said next task in said queue becoming ready for execution subsequent to said prior task completing, operating said first timer thread to dispatch said next task.

7. The method of claim 1, further comprising:

operating a user thread to add tasks to said queue and said timer thread selectively to remove and reschedule tasks on said queue.

8. A system for scheduling tasks for execution, comprising:

a queue of tasks ordered by scheduled time for execution;

a timer thread for monitoring status of tasks in said queue and for selectively dispatching tasks;

a guard thread for monitoring status of tasks in said queue and for selectively creating timer threads;

said guard thread responsive to a next task in said queue becoming ready for execution while a first timer thread is still processing a prior task for creating a new timer thread to dispatch said next task and for marking said first timer thread for closure; and

said first timer thread closing responsive to said prior task completing.

9. The system of claim 8, further comprising:

said first timer thread operating responsive to said next task in said queue becoming ready for execution subsequent to said prior task completing to dispatch said next task.

10. The system of claim 8, further comprising:

said new timer thread monitoring status of tasks in said queue.

11. The system of claim 8, further comprising:

said guard task selectively setting and resetting a boolean value in timer threads, with said boolean value being set in a timer thread and said boolean value being reset to mark a prior timer thread for closure.

12. The system of claim 11, further comprising:

said guard thread monitoring status of tasks in said queue only while said first timer thread is processing a task.

13. The system of claim 12, further comprising:

a user thread for adding tasks on said queue, said timer thread further for selectively removing and rescheduling tasks on said queue.

14. A computer program product for scheduling tasks for execution, said computer program product comprising:

a computer readable medium;

first program instructions to order tasks in a queue;

second program instructions to provide a timer thread for monitoring status of tasks in said queue and to selectively dispatch tasks;

third program instructions to provide a guard thread for monitoring status of tasks in said queue and to selectively open timer threads;

fourth program instructions to operate said guard thread responsive to a next task in said queue becoming ready for execution while a first timer thread is still processing a prior task to create a new timer thread for dispatching said next task and to mark said first timer thread for closure;

fifth program instructions responsive to said prior task completing, to close said first timer thread; and

wherein

said first, second, third, fourth, and fifth program instructions are recorded on said computer readable medium.

15. The computer program product of claim 14, further comprising:

sixth program instructions responsive to said next task in said queue becoming ready for execution subsequent to said prior task completing, to operate said first timer thread to dispatch said next task; and

wherein

said sixth program instructions are recorded on said computer readable medium.

16. The computer program product of claim 14, further comprising:

sixth program instructions to operate said new timer thread to monitor status of tasks in said queue; and

wherein

said sixth program instructions are recorded on said computer readable medium.

17. The computer program product of claim 14, further comprising:

sixth program instructions to operate said guard task for selectively setting and resetting a boolean value in timer threads, with said boolean value being set in a timer thread and said boolean value being reset to mark a prior timer thread for closure; and

wherein

said sixth program instructions are recorded on said computer readable medium.

18. The computer program product of claim 17, further comprising:

seventh program instructions to operate said guard thread to monitor status of tasks in said queue only while said first timer thread is processing a task; and

wherein

said seventh program instructions are recorded on said computer readable medium.

19. The computer program product of claim 14, further comprising:

sixth program instructions to operate a user thread to add tasks to said queue and said timer thread selectively to remove and reschedule tasks on said queue; and

wherein

said sixth program instructions are recorded on said computer readable medium.