Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
1998-08-28
2001-02-13
Alam, Hosain T. (Department: 2771)
Data processing: database and file management or data structures
Database design
Data structure types
C709S241000, C714S012000
Reexamination Certificate
active
06189007
ABSTRACT:
FIELD OF INVENTION
The present invention relates to the control access to shared resources in computer systems and more particularly to a method for performing high performance locking facility in a loosely coupled environment.
BACKGROUND OF THE INVENTION
In both a tightly coupled and a loosely coupled environment, messages are needed to orchestrate the execution of each transaction. This is particularly true with partitioned systems where all updates are done by the single server for a partition, lock management for resources of the partition is done at this server and locks are held by transactions running at the server.
One method of synchronizing tasks in a data sharing environment is known as locking. By this method, a task first obtains access to a data structure known as a lock and then indicates the type of access that is desired in order to either read or modify data in the database that is protected by the lock. The task then has access to the protected data with the specified type of access. Other tasks are prevented from accessing the protected data until a lock is obtained.
Currently, many systems use a Multipath Lock Facility or MPLF which is a kind of input/output device. MPLF serializes accesses to locks resided on the same device. The performance is also limited by the input/output latency. To alleviate this performance problem in some installations, locks are distributed among multiple MPLFs so that concurrent accesses can be achieved. However, as the lock request rate increases, the number of MPLFs required to maintain a reasonable system throughput also increases and the cost becomes prohibitive. As a consequence a better locking facility is needed that can address these cost and performance issues. The facility provides a means to construct an adjunct lock table for, in one embodiment up to 64 users, based on the list structure. There is one list entry for each lock that is currently being held by some users. List entries are named so that the lock name is stored in the associated list entry name object. Information about lock state, pending lock requests, lock holders, and first requestor in the waiting queue of a particular lock is maintained in the list lock entry.
This application is being filed at the same time as related applications, Ser. Nos. 09/143,328; 09/143,632 and 09/141,544.
SUMMARY OF THE INVENTION
A method and apparatus of assigning and releasing locks, in a network computing environment having a plurality of central processing units coupled to a high performance locking facility. The method comprises of the steps of first receiving and processing a lock operation synchronous to any requesting central processor unit requesting a lock and then recording lock names and lock states in entry records of a lock table based on the requests. When a request is being processed, providing high- speed searching to search any particular lock entry in the table and altering and modifying the table accordingly. Finally an appropriate response and the status of the lock state will be generated and sent to other requestors requesting the lock.
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Boonie Mark A.
Nick Jeffrey M.
Sutton Peter G.
Wilkinson Wendell W.
Yeh Phil C.
Alam Hosain T.
International Business Machines - Corporation
Neff Lily
Wojnicki, Jr. Andrew J.
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