Deadlock (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-7th Edition 18.8 ©Silberscha乜，Korth and SudarshanDatabase System Concepts - 7 18.8 ©Silberschatz, Korth and Sudarshan th Edition Deadlock (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