Real time synchronization in multi-threaded computer systems

• US 6,587,955 B1
• Filed: 02/01/2000
• Issued: 07/01/2003
• Est. Priority Date: 02/26/1999
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Foote, William, Long, Dean Roy Ernest, Fresko, Nedim
• Primary Examiner(s): Lee, Thomas
• Assistant Examiner(s): SURYAWANSHI, SURESH
• Application Number:
  US09/495,820
• Time in Patent Office: 1,246 Days
• Field of Search: 713/400, 714/39, 709/107
• US Class Current: 713/400
• CPC Class Codes: G06F 9/52 Program synchronisation; Mutual exclusion, e.g. by means of semaphores

Abstract

Methods and apparatus for implementing priority inversion avoidance protocols and deterministic locking where an API is used to select objects in a multi-threaded computer system are disclosed. In one aspect of the invention, an enhanced monitor is associated with one or more selected objects by way of an associated API. The enhanced monitor is arranged to set behavior for a lock associated with the selected objects as determined by a user defined behavior object included within the enhanced monitor. In this arrangement, only the selected one or more objects are associated with the enhanced monitor.

Claims

1. In a multi-threaded computing system that includes a plurality of threads and a plurality of objects substantially all of which have an associated standard monitor, wherein the standard monitor provides a lock mechanism suitable for locking the associated object when a thread enters the standard monitor such that no other thread can enter the standard monitor until released by the thread, a method of setting desired locking behavior for one or more of the objects, comprising:

associating an enhanced monitor with the one or more objects, wherein the enhanced monitor is arranged to set appropriate locking behavior for the one or more objects as determined by a user defined behavior object included within the enhanced monitor.

2. A method as recited in claim 1, wherein the one or more objects are identified by a user.

3. A method as recited in claim 1, wherein the selected object includes an object header that includes an enhanced monitor pointer field.

4. A method as recited in claim 3, wherein the enhanced monitor pointer field includes an enhanced monitor pointer used to identify the corresponding enhanced monitor having an appropriate behavior object.

5. A method as recited in claim 4, wherein each of the plurality of threads has an associated priority, wherein a thread'"'"'s priority is indicative of the importance of the thread'"'"'s execution.

6. A method as recited in claim 5, wherein the behavior object is arranged to selectably provide a priority inversion avoidance protocol to the associated object.

7. A method as recited in claim 6, wherein the priority inversion avoidance protocol is selected from the group comprising:

priority inheritance protocol and priority ceiling protocol.

8. A method as recited in claim 7, wherein the object is a JAVA object.

9. In a multi-threaded computing system that includes a plurality of threads and a plurality of objects substantially all of which have an associated standard monitor, wherein the standard monitor provides a standard synchronization on an associated object by providing a lock mechanism suitable for locking the associated object when a thread enters the standard monitor such that no other thread can enter the standard monitor until released by the thread, a method of enhanced synchronization on a selected object, comprising:

determining if the object requires enhanced synchronization;

identifying an enhanced monitor suitably arranged to provide the enhanced synchronization; and

associating the enhanced monitor with the object;

wherein the enhanced monitor is arranged to set behavior for the object as determined by a user defined behavior object included within the enhanced monitor.

10. A method as recited in claim 9, wherein the object is identified by the user.

11. A method as recited in claim 10, wherein the object includes an object header that includes an enhanced monitor pointer field.

12. A method as recited in claim 11, wherein the enhanced monitor pointer field includes an enhanced monitor pointer used to identify the corresponding enhanced monitor having an appropriate behavior object.

13. A method as recited in claim 12, wherein each of the plurality of threads has an associated priority, wherein a thread'"'"'s priority is indicative of the importance of the thread'"'"'s execution.

14. A method as recited in claim 13, wherein the behavior object is arranged to selectably provide a priority inversion avoidance protocol to the associated object.

15. A method as recited in claim 14, wherein the priority inversion avoidance protocol is selected from the group comprising:

priority inheritance protocol and priority ceiling protocol.

16. A method as recited in claim 15, wherein the object is a JAVA object.

17. A method as recited in claim 9, wherein the standard monitor includes a lightweight monitor pointer when the object in uncontended.

18. A method as recited in claim 9, wherein the standard monitor includes a heavyweight monitor pointer when the object is contended, wherein the heavyweight monitor provides standard synchronization behavior for the contending objects.

19. A method as recited in claim 9, wherein the object header includes an enhanced monitor flag indicative of the object requiring the enhanced monitor.