Processes Synchronization Part II: Deadlocks

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Questions and Answers

What is the term used to describe a situation where a process requests resources that are held by other waiting processes?

Resource preemption

Resource contention

Resource deadlock (correct)

Resource utilization

What condition for deadlock arises when a process holding at least one resource is waiting to acquire additional resources held by other processes?

Hold and wait (correct)

Circular wait

No preemption

Mutual exclusion

Which condition for deadlock arises when a set of processes are each waiting for a resource held by another process in the set?

Hold and wait

Mutual exclusion

No preemption

Circular wait (correct)

What term describes the situation where only one process at a time can use a resource?

Mutual exclusion Signup and view all the answers

What does the 'Safety Algorithm' used to check?

If a system is in a safe state for all processes to complete their tasks Signup and view all the answers

Which algorithm is used to identify and recover from deadlock?

Deadlock Detection Algorithm Signup and view all the answers

What does the 'Wait-for graph' represent in deadlock detection?

Processes and waiting relationships using nodes and edges Signup and view all the answers

Which data structures are used for resource management?

Available, Allocation, and Request matrices Signup and view all the answers

How can recovery from deadlock be achieved through resource preemption?

Resources are forcefully taken away from one process and given to another Signup and view all the answers

What does the 'Detection Algorithm' check for?

Existence of deadlock using vectors and resource availability checks Signup and view all the answers

What scenario can lead to deadlock?

Simultaneous conditions cause processes to be unable to complete their tasks Signup and view all the answers

What does the 'Resource-Request Algorithm for Process Pi' outline?

How a process can request resources and check availability Signup and view all the answers

'Banker’s Algorithm Example' demonstrates the use of which algorithm on a specific system configuration?

'Safety Algorithm' Signup and view all the answers

What can be achieved through process termination in recovery from deadlock?

Deadlocked processes are terminated in an order based on factors such as priority, computation time, and resource usage. Signup and view all the answers

What is the primary method for modeling deadlock situations in the context of multi-threading and resource allocation?

Representing processes and resource types as vertices in a graph Signup and view all the answers

When does a deadlock occur in the context of resource-allocation graphs?

When a cycle exists in the resource-allocation graph Signup and view all the answers

Which method involves requiring a process to request all resources before execution to prevent deadlocks?

Resource preemption Signup and view all the answers

Which algorithm is mentioned as a way of implementing deadlock avoidance in the text?

Banker's algorithm Signup and view all the answers

What does the banker's algorithm ensure in relation to deadlock avoidance?

It ensures that the system can deliver all requested resources to a process without entering a deadlock state Signup and view all the answers

In the context of deadlock prevention, what does imposing a total ordering of resource requests involve?

Ensuring that requests for resources are always made in the same order Signup and view all the answers

What is the purpose of the resource-allocation graph algorithm?

To detect potential deadlocks in a system Signup and view all the answers

What is one of the prevention methods for deadlocks mentioned in the text?

Requiring a process to request all resources before execution Signup and view all the answers

What does avoidance methods for deadlocks entail?

Guaranteeing that all requested resources are being delivered to processes without entering a deadlock state. Signup and view all the answers

What are represented as vertices in a resource-allocation graph?

Processes and resource types Signup and view all the answers

What is one of the key requirements of the banker's algorithm?

Processes must declare their maximum need for each resource type. Signup and view all the answers

Study Notes

The text discusses the concept of deadlocks in the context of multi-threading and resource allocation.
Two threads, P1 (thread_one) and P2 (thread_two), are waiting for resources held by each other in a deadlock situation.
The text then introduces the concept of resource-allocation graphs to model deadlock situations.
A process (or thread) and a resource type are represented as vertices in a graph, and edges represent requests and assignments of resources.
A deadlock occurs when a cycle exists in the resource-allocation graph.
Prevention methods for deadlocks include requiring a process to request all resources before execution or imposing a total ordering of resource requests.
Avoidance methods for deadlocks involve ensuring that a system will never enter an unsafe state, by checking if a system can deliver all requested resources to a process without entering a deadlock state.
The text mentions the resource-allocation graph algorithm and the banker's algorithm as a way of implementing deadlock avoidance.
The text provides a brief description of the banker's algorithm, including its requirements, data structures, and steps.

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Description

This quiz covers the concept of deadlocks in a multiprogramming environment where processes compete for finite resources. It explores the scenario where processes enter a waiting state due to unavailable resources held by other waiting processes.