GATE 2016 Session 5 CS Q51
Consider the following two phase locking protocol. Suppose a transaction T accesses (for
read or write operations),a certain set of objects {O1,.... Ok }. This is done in the following
manner:
Step 1. T acquires exclusive locks to O1, ..., Ok in increasing order of their addresses.
Step 2. The required operations are performed.
Step 3. All locks are released.
This protocol will
(A) guarantee serializability and deadlock-freedom
(B) guarantee neither serializability nor deadlock-freedom
(C) guarantee serializability but not deadlock-freedom
(D) guarantee deadlock-freedom but not serializability
step 1. T acquire exclusive locks to O1,O2,O3,O4........Ok in increasing order then Circular wait not possible.
step 2. the required operation are performed
step 3. released
above steps does not perfrom Deadlock.
and all 2 PL are serilizable.
It will ensure serializablity but deadlock chances will be there so option C
If the locks are acquired in the order, there will be no circular wait and hence no deadlock.
So A
step 1. T acquire exclusive locks to O1,O2,O3,O4........Ok in increasing order then Circular wait not possible.
step 2. the required operation are performed
step 3. released
above steps does not perfrom Deadlock
and all 2 PL are serilizable