Lock management thread pools for distributed data systems

• US 7,093,230 B2
• Filed: 07/24/2002
• Issued: 08/15/2006
• Est. Priority Date: 07/24/2002
• Status: Active Grant

• Current Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: E, Sandhya, Kumar, Ajay, K, Venugopal Rao
• Primary Examiner(s): DAS, CHAMELI
• Application Number:
  US10/202,334
• Publication Number:
  US 20040019892A1
• Time in Patent Office: 1,483 Days
• Field of Search: 717/131, 717/127, 717100-103, 710/200, 710/28, 711/152, 711/164, 707/8, 707/10, 707/103, 709226-229, 709217-219, 709/210, 709/205, 718/104
• US Class Current: 717/100
• CPC Class Codes: G06F 16/2343 Locking methods, e.g. distributed locking or locking implementation details
• CPC Class Codes: G06F 9/52 Program synchronisation; Mutual exclusion, e.g. by means of semaphores

Abstract

A distributed data system may include a plurality of nodes one or more of which may include at least one multi-threaded process operable to access portions of distributed data. A lock mechanism may grant locks to the multi-threaded processes for portions of the distributed data. Only a process holding a lock may access a portion corresponding to the lock. Threads of other processes may not access the portion. A process may include a lock management thread pool dedicated to managing locks for portions of the distributed data for access by other threads of the process. Each lock management thread of the lock management thread pool may request a lock for a portion of distributed data on behalf of the process. The process may hold one or more locks for portions of distributed data corresponding to one or more lock management threads of the lock management thread pool.

Claims

1. A distributed data system, comprising:

a plurality of network nodes each configured to execute one or more processes;

a data store configured to store primary data accessible by the processes; and

a lock mechanism coupled to the data store and configured to lock access to portions of the primary data, wherein the lock mechanism is configured to grant a lock to a requester for one of the processes for a primary data portion stored by the data store, wherein the lock mechanism is configured to prevent other processes from accessing the primary data portion while the requester is granted the lock;

wherein each of the processes is configured to maintain a thread pool of lock management threads, wherein each of the lock management threads is configured to be a requester on behalf of its process for a lock from the lock mechanism for a portion of the primary data.

2. The distributed data system as recited in claim 1, wherein each of the processes is configured so that when one of its lock management threads obtains a lock for a primary data portion one or more other threads of the process requesting access to the primary data portion can access the primary data portion while the lock is held for that process.

3. The distributed data system as recited in claim 2, wherein each of the processes is configured to:

increment a count corresponding to ,the lock for the portion of the primary data in response to a thread of the process requesting access to the primary data portion;

decrement the count in response to a thread completing access to the locked portion of the primary data; and

wherein the lock management thread that acquired the lock is configured to release the lock in response to the corresponding count reaching an initial value.

4. The distributed data system as recited in claim 1, wherein each of the lock management threads for one of the processes is configured to release a previously acquired lock when no more threads of that process request access to the primary data portion corresponding to the lock.

5. The distributed data system as recited in claim 1, wherein the lock mechanism is configured to allow only the requester for a lock to release the lock for the corresponding portion of the primary data.

6. The distributed data system as recited in claim 1, wherein each of the lock management threads is configured to hold the lock it acquires for its process until that process receives a request to release the lock.

7. The distributed data system as recited in claim 1, wherein each of the lock management threads is configured to release the lock it acquired for its process in response to an invalidate request from another thread in its process.

8. The distributed data system as recited in claim 1, wherein the plurality of network nodes comprise one or more application servers of a multi-tiered enterprise system.

9. The distributed data system as recited in claim 1, wherein the one of the processes comprises a virtual machine for a platform-independent language.

10. The distributed data system as recited in claim 1, wherein a portion of the primary data, stored by the data store represents state information of a client-server session.

11. The distributed data system as recited in claim 1, wherein if a requester for a process holds a lock for a portion of the primary data, the lock mechanism is configured to buffer one or more requests for the lock for that portion of the primary data from one or more other requesters for one or more other processes.

12. The distributed data system as recited in claim 11, wherein in response to the requester releasing the lock for the portion of the primary data, the lock mechanism is configured to grant the lock for that portion of the primary data to a next buffered requester for that primary data portion.

13. A computing system comprising:

a processor;

memory comprising program instructions executable by the processor to implement;

a process configured to access portions of distributed data stored within a distributed data store accessible to other processes;

wherein the process is configured to maintain a thread pool of lock management threads, wherein each of the lock management threads is configured to request a lock for one of the portions of distributed data on behalf of the process from a lock mechanism of the distributed data store.

14. The computing system as recited in claim 13, wherein the process is configured so that when one of its lock management threads obtains a lock for a distributed data portion one or more other threads of the process requesting access to the primary data portion can access the distributed data portion while the lock is held for the process.

15. The computing system as recited in claim 14, wherein the process is configured to:

increment a count corresponding to a distributed data portion lock for the process in response to a thread of the processes requesting access to the locked distributed data portion;

decrement the count in response to a thread of the process completing access to the locked distributed data portion; and

wherein the lock management thread that acquired the lock is configured to release the lock in response to the corresponding count reaching an initial value.

16. The computing system as recited in claim 13, wherein each of the lock management threads for the process is configured to release a previously acquired lock when no more threads of that process request access to the distributed data portion corresponding to the lock.

17. The computing system as recited in claim 13, wherein each of the lock management threads is configured to hold the lock it acquires for the process until the process receives a request to release the lock.

18. The computing system as recited in claim 13, wherein each of the lock management threads is configured to release the lock it acquired for the process in response to an invalidate request from another thread of the process.

19. The computing system as recited in claim 13, wherein the memory comprises program instructions executable by the processor to implement an application server for a multi-tiered enterprise system, wherein the process is configured to execute within the application server.

20. The computing system as recited in claim 13, wherein the process comprises a virtual machine for a platform-independent language.

21. The computing system as recited in claim 13, wherein a portion of the distributed data represents state information of a client-server session.

22. A computer implemented method comprising:

a requesting thread of a process requesting access within the process to data corresponding to a portion of primary data stored in a distributed data store;

in response to the thread requesting access, the process selecting a lock management thread from a lock management thread pool to request a lock for the portion of primary data;

the selected lock management thread acquiring the lock for the portion of primary data; and

in response to the selected lock management thread acquiring the lock, the requesting thread accessing the portion of primary data.

23. The method as recited in claim 22, further comprising one or more other threads of the process accessing the portion of the primary data while the lock is granted to the process.

24. The method as recited in claim 22, further comprising, if no more threads of the process require access to the portion of distributed data, the lock management thread releasing the lock on behalf of the process.

25. The method as recited in claim 22, further comprising:

incrementing a count corresponding to the portion of primary data within the process for each thread of the process requesting access to that portion of primary data;

decrementing the count corresponding to the portion of primary data within the process for each thread of the process completing access to that portion of primary data; and

the lock management thread releasing the lock for the process in response to the count reaching an initial value.

26. The method as recited in claim 22, further comprising the process holding the lock until requested to release the lock.

27. The method as recited in claim 22, further comprising:

another thread of the process requesting release of the lock for the portion of primary data;

the lock management thread releasing the lock for the portion on behalf of the process in response to the request to release the lock.

28. An article of manufacture comprising program instructions executable to implement:

a requesting thread of a process requesting access within the process to data corresponding to a portion of primary data stored in a distributed data store;

in response to the thread requesting access, the process selecting a lock management thread from a lock management thread pool to request a lock for the portion of primary data;

the selected lock management thread acquiring the lock for the portion of primary data; and

in response to the selected lock management thread acquiring the lock, the requesting thread accessing the portion of primary data.

29. The article of manufacture as recited in claim 28, wherein the program instructions are further executable to implement one or more other threads of the process accessing the portion of the primary data while the lock is granted to the process.

30. The article of manufacture as recited in claim 28, wherein the program instructions are further executable to implement, if no more threads of the process require access to the portion of distributed data, the lock management thread releasing the lock on behalf of the process.

31. The article of manufacture as recited in claim 28, wherein the program instructions are further executable to implement:

incrementing a count corresponding to the portion of primary data within the process for each thread of the process requesting access to that portion of primary data;

decrementing the count corresponding to the portion of primary data within the process for each thread of the process completing access to that portion of primary data; and

the lock management thread releasing the lock for the process in response to the count reaching an initial value.

32. The article of manufacture as recited in claim 28, wherein the program instructions are further executable to implement the process holding the lock until requested to release the lock.

33. The article of manufacture as recited in claim 28, wherein the program instructions are further executable to implement:

another thread of the process requesting release of the lock for the portion of primary data;

the lock management thread releasing the lock for the portion on behalf of the process in response to the request to release the lock.