The Two-Phase Locking Protocol(Cont) T lock-X(A) read(a) lock-S(B) read ( B write(A) unlock(A) lock-X(A) read(A) write(A) unlock(A) lock-S(A) ead(A) 标 Database System Concepts 3rd Edition 16.10 OSilberschatz, Korth and SudarshanDatabase System Concepts 3 16.10 ©Silberschatz, Korth and Sudarshan rd Edition The Two-Phase Locking Protocol (Cont.)