Strict Two-Phase Locking

If locking is two-phase:

T1	T2
X(A)
R(A)
W(A)
	X(A)
X(B)
R(B)
W(B)
U(B)
U(A)
	X(B)
	R(A)
commit
	W(A)
	R(B)
	W(B)
	U(B)
	U(A)
	commit

• All unlocks moved to the end of each transaction.

• 2PL has introduced a delay in T2 resulting in a serializable schedule.