Multilevel locking system and method

Details Multilevel locking system and method Multilevel locking system and method

1989-11-13

1992-11-03

Fleming, Michael R.

Boots, shoes, and leggings

395725, 3642468, 3642281, 364DIG1, 3649692, 364DIG2, G06F 13376

Patent

active

051612275

ABSTRACT:
A multi-processor computer system in which each processor is under the control of separate system software and access a common database. A two level lock management system is used to prevent data corruption due to unsychronized data access by the multiple processors. By this system, subsets of data in the database are assigned respectively different lock entities. Before a task running on one of the processors access data in the database it first requests permission to access the data in a given mode with reference to the appropriate lock entity. A first level lock manager handles these requests synchronously, using a simplified model of the locking system having shared and exclusive lock modes to either grant or deny the request. All requests are then forwarded to a second level lock manager which grants or denies the request based on a more robust model of the locking system and queues denied requests. The denied requests are granted, in turn, as the tasks which have been granted access finish processing data in the database.

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