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Patent Title: System and method for reducing research time through a lock wait matrix

Assignee: IBM
Patent Number: US6223200
Issue Date: 04-24-2001
Application Number:
File Date:04-11-1994

Abstract: A shared file computer system has multiple users, and two or more transactions established by the users may contend for the same resource. Such contention may result in a deadlock condition. To search for such deadlocks, the system maintains a lock wait matrix which lists which transactions are waiting on which other transactions. The matrix represents a hierarchical wait tree. A deadlock is present when the top node transaction in the tree also occurs lower in the tree. In such a case, either the top node transaction or any other transaction in the path or branch between the two occurrences of the top node transaction is cancelled to resolve the deadlock represented by this path. However if the intermediary node is cancelled to resolve this deadlock, a similar deadlock can occur in another path and must be resolved also. There can be thousands of paths in the tree to be searched for such a deadlock condition, and to optimize the deadlock search after the intermediary node is cancelled, transactions leading from this intermediary node are not examined. Nevertheless, all deadlock conditions are detected.


Link to USPTO

IBM Pledge dated 1/11/2005