System and method for scheduling tasks for execution

• US 7,793,299 B2
• Filed: 08/30/2005
• Issued: 09/07/2010
• Est. Priority Date: 08/30/2005
• Status: Expired due to Fees

• Current Assignee: LinkedIn Corporation (Microsoft Corporation)
• Original Assignee: International Business Machines Corporation
• Inventors: Howland, Michael J., Howland, Melissa K.
• Primary Examiner(s): An; Meng-Ai
• Assistant Examiner(s): Lee; Adam
• Application Number:
  US11/214,604
• Publication Number:
  US 20070050771A1
• Time in Patent Office: 1,834 Days
• Field of Search: 718104-105, 718/108, 710/200, 709/100
• US Class Current: 718/108
• 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 by a computer processor tasks that are scheduled to execute at a scheduled time in a queue;

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

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

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

operating by a computer processor said guard thread 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

responsive to said prior task completing, closing by a computer processor said first timer thread,

wherein the method being performed by a data processing system having at least one computer processor.

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 by a computer processor said first timer thread to dispatch said next task.

3. The method of claim 1, further comprising:

operating by a computer processor said new timer thread to monitor status of tasks in said queue.

4. The method of claim 1, further comprising:

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

5. The method of claim 1, further comprising:

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

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

a computer processor coupled to a memory wherein the computer processor is programmed to perform;

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 according to the scheduled time for execution;

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 at a scheduled time while a first timer thread is still processing a prior task for creating a new timer thread to dispatch said next task at the scheduled time and for marking said first timer thread for closure;

said guard thread 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

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

7. The system of claim 6, 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.

8. The system of claim 6, further comprising:

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

9. The system of claim 6, further comprising:

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

10. The system of claim 9, further comprising:

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

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

a computer readable storage medium;

first program instructions to order tasks in a queue that are scheduled to execute at a scheduled time;

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 at a scheduled time while a first timer thread is still processing a prior task to create a new timer thread for dispatching said next task at the schedule time and to mark said first timer thread for closure;

fifth 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;

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

wherein

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

12. The computer program product of claim 11, further comprising:

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

13. The computer program product of claim 11, further comprising:

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

wherein

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

14. The computer program product of claim 11, 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 storage medium.

15. The computer program product of claim 11, further comprising:

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