Deadlock detection and recovery in Operating Systems - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Deadlock Detection

Which of the following best describes the purpose of deadlock detection in operating systems?

A To identify deadlocks after they have occurred and take action to resolve them

B To avoid deadlocks by careful resource allocation before they happen

C To prevent deadlocks by denying resource requests that could cause them

D To ignore deadlocks since they rarely occur in modern systems

💡 Hint

Think about what happens after a deadlock has already happened.

Deadlock detection is about finding deadlocks that have already occurred so the system can recover. Prevention and avoidance are different strategies.

📋 Factual

intermediate

Deadlock Recovery Methods

Which of the following is NOT a common method used for deadlock recovery?

A Terminating one or more processes involved in the deadlock

B Increasing the number of resources available to all processes

C Preempting resources from some processes and reallocating them

D Rolling back processes to a safe state before deadlock

💡 Hint

Consider which option is not a direct recovery technique.

Increasing resources is a system change, not a recovery method. Recovery involves process termination, resource preemption, or rollback.

🔍 Analysis

advanced

Detecting Deadlock with Resource Allocation Graphs

Given a resource allocation graph with cycles, which statement is true about deadlock detection?

A Deadlock can only be detected if the graph has no cycles

B A cycle in the graph always means a deadlock exists

C Cycles are irrelevant to deadlock detection

D A cycle in the graph means deadlock exists if each resource has only one instance

💡 Hint

Think about how resource instances affect deadlock detection.

Cycles in resource allocation graphs indicate deadlocks if resources have a single instance. Multiple instances require more complex checks.

❓ Comparison

advanced

Comparing Deadlock Detection Algorithms

Which of the following statements correctly compares the wait-for graph and the resource allocation graph methods for deadlock detection?

A Resource allocation graphs are simpler and used only when each resource has one instance

B Wait-for graphs represent processes and resources separately, while resource allocation graphs do not

C Wait-for graphs are simpler and used when each resource has multiple instances

D Resource allocation graphs cannot detect deadlocks involving multiple instances of resources

💡 Hint

Consider the complexity and usage scenarios of each graph type.

Wait-for graphs are simpler and used when each resource has multiple instances. Resource allocation graphs use simple cycle detection when each resource has one instance.

❓ Reasoning

expert

Choosing Deadlock Recovery Strategy

An operating system detects a deadlock involving multiple processes and resources. Which recovery strategy minimizes system disruption while ensuring deadlock resolution?

A Preempt resources from processes with the lowest priority and reallocate them

B Terminate all processes involved in the deadlock immediately

C Ignore the deadlock and wait for processes to timeout

D Rollback all processes to their initial states

💡 Hint

Think about balancing system stability and deadlock resolution.

Preempting resources from low priority processes reduces disruption compared to terminating all or rolling back all processes. Ignoring deadlock causes system hang.