Deadlock avoidance (Banker's algorithm) in Operating Systems - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding the Safe State in Banker's Algorithm

In the Banker's algorithm, what does it mean for the system to be in a safe state?

A The system can allocate resources to all processes in some order without causing a deadlock.

B The system has allocated all resources to processes, so no resources are free.

C The system has no processes currently requesting resources.

D The system is currently in a deadlock but can recover automatically.

💡 Hint

Think about what the algorithm tries to ensure before granting resource requests.

A safe state means the system can allocate resources to each process in some order and avoid deadlock. It does not mean no requests or all resources are allocated.

📋 Factual

intermediate

Key Data Structures in Banker's Algorithm

Which of the following is not a key data structure used in the Banker's algorithm?

A Request queue listing processes waiting for resources in order.

B Allocation matrix showing resources currently allocated to each process.

C Maximum matrix showing maximum demand of each process.

D Available vector showing currently free resources.

💡 Hint

Recall the matrices and vectors used to track resource allocation and needs.

The Banker's algorithm uses Available, Allocation, Maximum, and Need matrices/vectors. It does not use a request queue to order waiting processes.

🔍 Analysis

advanced

Analyzing Resource Allocation Safety

Given the following state:

Available = [3, 2, 2]
Allocation = [[0, 1, 0], [2, 0, 0], [3, 0, 2], [2, 1, 1], [0, 0, 2]]
Maximum = [[7, 5, 3], [3, 2, 2], [9, 0, 2], [2, 2, 2], [4, 3, 3]]

If process P1 requests [1, 0, 2], will granting this request keep the system in a safe state?

A Yes, because the request is less than or equal to the available resources.

B No, because the request exceeds the process's maximum demand.

C No, because the available resources are insufficient to grant the request.

D Yes, because after allocation, the system can find a safe sequence.

💡 Hint

Check if the request is within maximum demand and available resources, then verify if a safe sequence exists after allocation.

The request by P1 is within its maximum demand and available resources. After hypothetically granting it, the system can find a safe sequence, so it remains safe.

❓ Comparison

advanced

Comparing Deadlock Avoidance and Deadlock Prevention

Which statement best distinguishes deadlock avoidance (like Banker's algorithm) from deadlock prevention?

A Deadlock avoidance blocks all resource requests, while prevention allows all requests without checks.

B Deadlock avoidance requires no knowledge of maximum resource needs, while prevention requires full knowledge.

C Deadlock avoidance dynamically checks resource allocation safety, while prevention imposes strict resource usage rules upfront.

D Deadlock avoidance always leads to deadlock, while prevention never allows deadlock.

💡 Hint

Think about how each approach handles resource requests and system state.

Deadlock avoidance algorithms like Banker's check if granting a request keeps the system safe before allocation. Prevention methods restrict resource usage to avoid unsafe states.

❓ Reasoning

expert

Reasoning About Banker's Algorithm Limitations

Which of the following is a fundamental limitation of the Banker's algorithm in practical operating systems?

A It works only when there is a single type of resource.

B It requires processes to declare their maximum resource needs in advance, which is often impractical.

C It allows unsafe states that may lead to deadlock.

D It cannot detect deadlocks once they occur in the system.

💡 Hint

Consider what information the algorithm needs to function correctly.

The Banker's algorithm needs each process to declare its maximum resource needs beforehand, which is difficult in real systems where needs may be unknown or change.