METHOD OF CONTROLLING THREAD ACCESS TO A SYNCHRONIZATION OBJECT

• US 20080155546A1
• Filed: 12/22/2006
• Published: 06/26/2008
• Est. Priority Date: 12/22/2006
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Ruemmler, Christopher P.
• Granted Patent: US 8,132,171 B2
• Time in Patent Office: Days
• US Class Current: 718/102
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms

Abstract

A method of controlling thread access to a synchronization object is described. The method comprises waking a sleeping first thread after release, by a second thread, of a synchronization object in a normal state and causing, by the first thread, the synchronization object to transition to a want-lock state, the synchronization object being acquirable by the first thread prior to being acquirable by the second thread.

Claims

1. A method of controlling thread access to a synchronization object, comprising:

waking a sleeping first thread after release, by a second thread, of a synchronization object in a normal state; and

causing, by the first thread, the synchronization object to transition to a want-lock state, the synchronization object being acquirable by the first thread prior to being acquirable by the second thread.

2. The method as claimed in claim 1, further comprising:

acquiring, by the first thread, the synchronization object; and

transitioning the synchronization object to the normal state.

3. The method as claimed in claim 1, wherein the waking comprises transitioning, by the second thread, the synchronization object to an in-flight state prior to waking the first thread.

4. The method as claimed in claim 1, further comprising:

acquiring, by a third thread, the synchronization object prior to the causing, by the first thread, the synchronization object to transition to a want-lock state; and

releasing, by the third thread, the synchronization object, wherein the synchronization object remains in the want-lock state.

5. The method as claimed in claim 4, further comprising:

acquiring, by the first thread, the synchronization object; and

transitioning the synchronization object to the normal state.

6. The method as claimed in claim 1, wherein the waking a sleeping first thread further comprises:

selecting a sleeping first thread from a sleeping thread list according to a predetermined order.

7. The method as claimed in claim 6, wherein the selecting according to a predetermined order comprises a first-in, first-out order.

8. The method as claimed in claim 1, further comprising:

causing, by the first thread, the synchronization object to transition to the normal state if the first thread sleeps prior to acquiring the synchronization object.

9. The method as claimed in claim 8, wherein the first thread sleeps if a spin threshold value is exceeded.

10. The method as claimed in claim 9, wherein the spin threshold value is exceeded by at least one of a number of attempts to acquire the synchronization object and an amount of time spent attempting to acquire the synchronization object.

11. The method as claimed in claim 9, wherein the spin threshold value is modified by a predetermined value for each unsuccessful attempt to acquire the synchronization object by the first thread.

12. The method as claimed in claim 1, wherein the synchronization object being acquirable by the first thread prior to the second thread comprises preventing, by the second thread, acquisition of the synchronization object by the second thread.

13. A system for controlling thread access to a synchronization object by at least one thread, comprising:

a synchronization object comprising an object wake state, wherein the object wake state comprises at least a normal state, an in-flight state, and a want-lock state; and

at least one thread comprising a thread wake state, the at least one thread arranged to attempt to acquire the synchronization object if at least one of;

(a) the object wake state is in-flight or normal and (b) the thread wake state indicates the thread is the most recent awakened thread and the object wake state is want-lock.

14. The system as claimed in claim 13, wherein the synchronization object further comprises a lock state, the lock state comprises at least a locked and unlocked state, and

wherein the at least one thread is further arranged to attempt to acquire the synchronization object lock state is unlocked.

15. The system as claimed in claim 14, wherein the at least one thread further comprises a spin threshold.

16. The system as claimed in claim 14, wherein the spin threshold comprises at least one of a number of attempts to acquire the synchronization object and an amount of time spent attempting to acquire the synchronization object.

17. The system as claimed in claim 14, wherein the system is further arranged to apply a predetermined formula to the spin threshold value for each unsuccessful attempt to acquire the synchronization object by the at least one thread.

18. The system as claimed in claim 13, wherein the at least one thread is further arranged to set the object wake state to in-flight after release of the synchronization object if the object wake state is normal and another thread is sleeping.

19. The system as claimed in claim 18, wherein the at least one thread is further arranged to wake the another sleeping thread.

20. A memory or a computer-readable medium storing instructions which, when executed by a processor, cause the processor to wake a sleeping first thread after release, by a second thread, of a synchronization object in a normal state;

and cause, by the first thread, the synchronization object to transition to a want-lock state, the synchronization object being acquirable by the first thread prior to being acquirable by the second thread.