Pitfalls of Lock-Based Protocols (Cont.) The potential for deadlock exists in most locking protocols.Deadlocks are a necessary evil. Starvation is also possible if concurrency control manager is badly designed.For example: A transaction may be waiting for an X-lock on an item,while a sequence of other transactions request and are granted an S-lock on the same item. The same transaction is repeatedly rolled back due to deadlocks. Concurrency control manager can be designed to prevent starvation. Database System Concepts-5th Edition,Oct 5,2006 16.7 @Silberschatz,Korth and SudarshanDatabase System Concepts - 5 16.7 ©Silberschatz, Korth and Sudarshan th Edition, Oct 5, 2006 Pitfalls of Lock-Based Protocols (Cont.) The potential for deadlock exists in most locking protocols. Deadlocks are a necessary evil. Starvation is also possible if concurrency control manager is badly designed. For example: A transaction may be waiting for an X-lock on an item, while a sequence of other transactions request and are granted an S-lock on the same item. The same transaction is repeatedly rolled back due to deadlocks. Concurrency control manager can be designed to prevent starvation