Question

Match List - I with List - II. 

List - I		List - II
A.	Deadlock prevention	I.	Banker's algorithm
B.	Deadlock detection	II.	Rollback
C.	Deadlock avoidance	III.	Circular wait
D.	Recovery from deadlock	IV.	High overheads

Choose the correct answer from the options given below:

• A. A-III, B-IV, C-I, D-II
• B. A-I, B-III, C-II, D-IV
• C. A-I, B-III, C-IV, D-II
• D. A-III, B-IV, C-II, D-I

Hint:

Avoidance = Banker's (The Banker never gives out more than he can cover). Prevention = Stopping the conditions (Circular Wait). Recovery = Undoing the damage (Rollback).

Answer 1

The Correct Option is A

Concept:
• Deadlock is a state in which a set of processes are blocked because each process is holding a resource and waiting for another resource held by another process.
• Prevention: Ensuring that at least one of the four necessary conditions (Mutual Exclusion, Hold and Wait, No Preemption, Circular Wait) can never hold.
• Avoidance: Dynamically deciding whether a resource allocation is safe using algorithms like Banker's.
• Detection and Recovery: Periodically checking the system state for cycles and taking corrective action.

Step 1: Match A with III (Deadlock Prevention)
Deadlock prevention works by denying one of the four necessary conditions. A classic method is preventing "Circular Wait" by imposing a linear ordering of resource types. So, A matches with III.

Step 2: Match C with I (Deadlock Avoidance)
Deadlock avoidance requires the OS to know in advance the maximum resources a process will ever request. The "Banker's Algorithm" uses this to ensure the system stays in a "safe state." So, C matches with I.

Step 3: Match D with II (Recovery from Deadlock)
Once a deadlock is detected, the system must recover. One way is "Rollback," which involves returning a process to a previous "safe" checkpoint so it can release its resources. So, D matches with II.

Step 4: Match B with IV (Deadlock Detection)
Detection algorithms maintain resource graphs and check for cycles. Because these checks are computationally expensive and run frequently, they impose "High Overheads" on the system. So, B matches with IV.