Deadlock detection and recovery in Operating Systems - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a deadlock in operating systems?

A deadlock is a situation where a group of processes are each waiting for resources held by the others, so none can proceed.

beginner

What is the main goal of deadlock detection?

The main goal of deadlock detection is to find if a deadlock has occurred in the system by checking resource allocation and process states.

intermediate

Name one common method used for deadlock detection.

One common method is the resource allocation graph, which shows processes and resources and helps identify cycles indicating deadlocks.

intermediate

What are two common strategies for deadlock recovery?

Two common strategies are: 1) Terminating one or more processes involved in the deadlock, 2) Preempting resources from some processes to break the deadlock.

intermediate

Why is deadlock prevention often not used in practice?

Deadlock prevention can be too restrictive and reduce system efficiency because it limits how resources are allocated.

What does a cycle in a resource allocation graph indicate?

A A deadlock

B A free resource

C A completed process

D An idle CPU

A cycle in the resource allocation graph means processes are waiting on each other in a loop, which is a deadlock.

Which of the following is NOT a deadlock recovery method?

A Rolling back processes

B Preempting resources

C Terminating processes

D Ignoring the deadlock

Ignoring the deadlock does not recover from it; recovery requires active steps like termination or preemption.

Deadlock detection algorithms typically run:

A Only at system startup

B Periodically during system operation

C Only when a process finishes

D Never

Deadlock detection algorithms run periodically to check if deadlocks have occurred.

Which resource state is most likely to cause deadlock?

A Resources held and requested simultaneously by processes

B Resources always free

C Resources never requested

D Resources allocated to only one process

Deadlocks happen when processes hold resources and wait for others held by other processes.

What is a disadvantage of terminating processes to recover from deadlock?

A It prevents deadlocks from happening

B It speeds up the system

C It may cause loss of work done by the terminated processes

D It frees all resources immediately

Terminating processes can cause loss of progress and data from those processes.

Explain how deadlock detection works and what happens after a deadlock is detected.

Think about how the system finds deadlocks and what it does next.

Describe two methods used to recover from deadlocks and their possible drawbacks.

Consider what happens when you stop or take resources from processes.