Synchronization and Deadlocks: Master the Concepts for Operating Systems

Question 1

Which of the following is NOT a synchronization primitive used in operating systems?

Accepted Answer

Array

Answer

Semaphore

Answer

Mutex

Answer

Condition variable

Question 2

Which of the following situations represents a deadlock?

Accepted Answer

Two processes waiting indefinitely for each other to release a lock

Answer

A process waiting for user input

Answer

A process waiting for a resource that is currently unavailable

Answer

A process waiting for a message from another process

Question 3

Which of the following is a deadlock prevention technique commonly used in operating systems?

Accepted Answer

Resource ordering

Answer

Hold-and-wait

Answer

Wound-wait

Answer

Timeout

Question 4

Which of the following is a synchronization primitive commonly employed to control access to shared resources in operating systems?

Accepted Answer

Mutex

Answer

Array

Answer

HashMap

Answer

Stack

Question 5

What is the primary purpose of a mutex in the context of operating systems?

Accepted Answer

To provide exclusive access to shared resources

Answer

To facilitate communication between processes

Answer

To prevent deadlocks

Answer

To manage memory allocation

Question 6

What is a starvation scenario in the context of operating systems?

Accepted Answer

When processes are forced to wait an unreasonably long time for a resource

Answer

When processes are unable to acquire the resources they need to execute

Answer

When processes are executed out of order, leading to incorrect results

Answer

When the operating system crashes due to a hardware failure

Question 7

Which of the following is a common deadlock prevention technique in operating systems?

Accepted Answer

Resource ordering

Answer

Preemption

Answer

Deadlock detection

Answer

Aging

Question 8

What is the primary objective of deadlock recovery in operating systems?

Accepted Answer

To restore the system to a consistent state after a deadlock has occurred.

Answer

To proactively identify and eliminate deadlocks as they arise.

Answer

To prevent deadlocks from occurring in the first place.

Answer

To allocate resources to processes in a manner that minimizes the probability of deadlocks.

Question 9

Which of the following is a primary advantage of utilizing condition variables in operating systems?

Accepted Answer

They enable processes to pause and wait until specific conditions are satisfied before continuing execution.

Answer

They offer a mechanism for inter-process communication.

Answer

They can be used to implement synchronization primitives, such as semaphores and mutexes.

Answer

They enhance operating system performance by reducing context switching.

Question 10

In the context of operating systems, what is the purpose of a lock?

Accepted Answer

To safeguard shared resources from concurrent access, ensuring data integrity.

Answer

To store data shared between processes, facilitating inter-process communication.

Answer

To signal the occurrence of specific events, triggering appropriate responses from the system.

Answer

To halt the execution of a process, preventing it from accessing resources.

Question 11

Which synchronization primitive is specifically designed for enforcing mutual exclusion?

Accepted Answer

Mutex

Answer

Semaphore

Answer

Condition variable

Answer

Event

Question 12

What is the primary purpose of a condition variable?

Accepted Answer

To synchronize threads based on shared conditions, allowing them to wait and be notified when conditions change.

Answer

To enforce mutual exclusion between threads, ensuring exclusive access to shared resources.

Answer

To signal events to multiple threads, facilitating inter-thread communication.

Answer

To create critical sections, protecting shared resources from concurrent access.

Question 13

Which technique is employed to proactively prevent deadlocks?

Accepted Answer

Deadlock prevention

Answer

Deadlock avoidance

Answer

Deadlock detection

Answer

Deadlock recovery

Question 14

Describe the key difference between a spinlock and a blocking lock.

Accepted Answer

Spinlocks actively wait (busy-wait) while blocking locks passively wait (sleep).

Answer

Blocking locks actively wait (busy-wait) while spinlocks passively wait (sleep).

Answer

Spinlocks are inherently faster than blocking locks.

Answer

Blocking locks are inherently faster than spinlocks.

Question 15

Which synchronization mechanism is primarily used to safeguard critical sections?

Accepted Answer

Mutex

Answer

Semaphore

Answer

Condition variable

Answer

Barrier

Question 16

Describe the primary purpose of a condition variable.

Accepted Answer

To notify threads of changes in shared resource state

Answer

To synchronize thread access to shared resources

Answer

To prevent deadlocks from occurring

Answer

To implement critical sections

Question 17

Which deadlock prevention technique involves requesting all necessary resources simultaneously?

Accepted Answer

Safe allocation

Answer

Resource ordering

Answer

Wait-die

Answer

Wound-wait

Question 18

Explain the fundamental distinction between deadlock avoidance and deadlock detection.

Accepted Answer

Deadlock avoidance proactively prevents deadlocks, while deadlock detection identifies existing deadlocks.

Answer

Deadlock detection proactively prevents deadlocks, while deadlock avoidance identifies existing deadlocks.

Answer

They represent equivalent concepts with different terminology.

Answer

Deadlock detection is inherently more efficient than deadlock avoidance.

Question 19

Which deadlock recovery mechanism involves terminating and restarting deadlocked processes?

Accepted Answer

Restart

Answer

Rollback

Answer

Compensation

Answer

Ignore

Question 20

Define a semaphore.

Accepted Answer

A synchronization mechanism that tracks available resources.

Answer

A data structure representing a process.

Answer

A technique to enforce mutual exclusion.

Answer

A strategy to prevent starvation.

Question 21

Which semaphore property ensures exclusive access to critical sections by only one thread at a time?

Accepted Answer

Mutual exclusion

Answer

Non-blocking

Answer

Fairness

Answer

Bounded waiting

Question 22

What is the primary purpose of the banker's algorithm in an operating system?

Accepted Answer

To detect and prevent deadlocks in resource allocation

Answer

To optimize resource scheduling for maximum throughput

Answer

To manage memory allocation and deallocation efficiently

Answer

To provide synchronization primitives for multi-threaded programming

Question 23

Which deadlock recovery technique involves restoring the system to a previous consistent state, discarding any unsaved changes?

Accepted Answer

Rollback

Answer

Restart

Answer

Compensation

Answer

Starvation

Question 24

Which synchronization primitive is primarily used to enforce mutual exclusion, ensuring that only one process can access a shared resource at a time?

Accepted Answer

Mutex

Answer

Semaphore

Answer

Condition variable

Answer

Barrier

Question 25

What is the main purpose of a semaphore in an operating system?

Accepted Answer

To control concurrent access to shared resources and prevent race conditions

Answer

To signal events or conditions between different parts of a program

Answer

To ensure fairness in resource allocation and prevent starvation

Answer

To implement mutual exclusion and protect critical sections

Question 26

What is the primary role of a condition variable in synchronization?

Accepted Answer

To signal when a resource or condition becomes available, allowing waiting threads to resume execution

Answer

To protect shared data structures from concurrent access and ensure data integrity

Answer

To enforce mutual exclusion and prevent multiple threads from accessing critical sections simultaneously

Answer

To prevent starvation by ensuring that all threads have a fair chance to acquire resources

Question 27

What is the primary purpose of the Banker's Algorithm in the context of deadlock prevention?

Accepted Answer

Predicting potential deadlocks based on resource allocation requests

Answer

Detecting existing deadlocks within a system

Answer

Recovering from deadlocks by terminating processes or preempting resources

Answer

Enforcing fairness in resource allocation to prevent starvation

Question 28

What is the primary function of a lock in the context of synchronization?

Accepted Answer

To restrict access to shared resources, preventing race conditions

Answer

To signal events or conditions to other threads or processes

Answer

To prevent infinite loops or deadlocks in multithreaded code

Answer

To enforce fairness in resource allocation and scheduling

Question 29

In multithreaded environments, what is the main function of condition variables?

Accepted Answer

Signal other threads to continue execution

Answer

Create new threads in the program

Answer

Exclusively lock shared resources

Answer

Terminate active threads

Question 30

Which of the following synchronization primitives is specifically designed to protect critical sections of code?

Accepted Answer

Mutex

Answer

Semaphore

Answer

Condition variable

Answer

Barrier

Question 31

Deadlocks occur when multiple processes or threads find themselves in a state where they:

Accepted Answer

Hold the same resource(s) and wait for each other to release them

Answer

Hold different resources and wait for each other to release them

Answer

Run on different processors and share no resources

Answer

Are all in a waiting state indefinitely

Question 32

Which deadlock prevention technique ensures that at least one resource is always available for allocation?

Accepted Answer

Resource ordering

Answer

Mutual exclusion

Answer

Hold and wait

Answer

Wound-wait

Question 33

A condition variable is primarily used for:

Accepted Answer

Blocking a process or thread until a specific condition becomes true

Answer

Signaling to other processes or threads that a condition has become true

Answer

Synchronizing access to a shared resource, preventing race conditions

Answer

Detecting and recovering from deadlocks

Question 34

A semaphore is a data structure that primarily tracks:

Accepted Answer

The number of available resources in a system

Answer

The number of processes or threads waiting for resources

Answer

The order in which processes or threads acquire resources

Answer

The state of processes or threads involved in deadlocks

Question 35

Which of the following is a property of safe states in a deadlock avoidance system?

Accepted Answer

All processes can be completed without causing a deadlock

Answer

No deadlocks can occur

Answer

No resources are wasted

Answer

All processes are in the running state

Question 36

What is the primary purpose of a semaphore?

Accepted Answer

To prevent multiple processes from accessing the same resource simultaneously

Answer

To allow multiple processes to execute concurrently

Answer

To signal when a specific event has occurred

Answer

To control the execution order of processes

Question 37

What is the Banker's algorithm primarily used for?

Accepted Answer

Preventing deadlocks

Answer

Detecting deadlocks

Answer

Resolving deadlocks

Answer

Measuring resource utilization

Question 38

What is a lock?

Accepted Answer

A variable that controls access to a resource

Answer

A data structure used for synchronization

Answer

A mechanism for preventing deadlocks

Answer

A way to communicate between processes

Question 39

Which of the following is a condition variable?

Accepted Answer

A variable that is used to signal a specific event has occurred

Answer

A variable that is used to lock a resource

Answer

A variable that is used to count the number of processes waiting for a resource

Answer

A variable that is used to store the state of a process

Question 40

What is the primary objective of synchronization in an operating system?

Accepted Answer

To ensure that multiple threads access shared resources in a controlled manner, preventing race conditions and data inconsistency.

Answer

To improve the overall performance of the system

Answer

To reduce the memory footprint of the system

Answer

To prevent deadlocks under all circumstances

Question 41

Which of the following is a potential disadvantage of using semaphores?

Accepted Answer

They can lead to priority inversion scenarios, where lower-priority threads indefinitely wait for higher-priority threads.

Answer

Semaphores are inherently difficult to implement.

Answer

Semaphores inherently cause deadlocks.

Answer

Semaphores can only be used for resource allocation.

Question 42

Which of the following is a key benefit of using condition variables?

Accepted Answer

They allow threads to wait for a specific condition to be met, enabling efficient synchronization and resource management.

Answer

Condition variables are easier to implement than semaphores.

Answer

Condition variables can be used to deliberately induce priority inversion.

Question 43

Which synchronization primitive is best suited for protecting a shared resource from simultaneous access by multiple threads, ensuring only one thread can access it at a time?

Accepted Answer

Mutex

Answer

Semaphore

Answer

Monitor

Answer

Condition variable

Question 44

A process is in a 'blocked' state because it is waiting for a resource to become available. What is the most likely cause of this state?

Accepted Answer

Deadlock

Answer

Context switch

Answer

Race condition

Answer

Thread starvation

Question 45

Consider a system with two processes, P1 and P2, each requesting resources A and B. P1 holds resource A and is waiting for B, while P2 holds resource B and is waiting for A. What is this situation called?

Accepted Answer

Deadlock

Answer

Race condition

Answer

Livelock

Question 46

Which of the following is NOT a necessary condition for a deadlock to occur?

Accepted Answer

Mutual exclusion

Answer

Preemption

Answer

Circular wait

Answer

Hold and wait

Question 47

What deadlock prevention technique involves ensuring that processes request all their resources at the same time?

Accepted Answer

Resource pre-allocation

Answer

Deadlock detection

Answer

Rollback

Answer

Resource ordering

Question 48

Which of these is NOT a common deadlock recovery technique?

Accepted Answer

Process migration

Answer

Rollback

Answer

Resource preemption

Answer

Process termination

Question 49

In a system using semaphores, what does a semaphore value of -2 indicate?

Accepted Answer

Two threads are currently blocked waiting for the semaphore.

Answer

The semaphore can be acquired by two more threads.

Answer

The semaphore is currently in use by two threads.

Question 50

A condition variable is primarily used for what purpose in synchronization?

Accepted Answer

Signaling threads that a specific condition has been met.

Answer

Implementing mutual exclusion.

Answer

Protecting shared resources from concurrent access.

Question 51

What is the primary difference between a semaphore and a mutex?

Accepted Answer

A semaphore can be incremented by multiple units, while a mutex can only be incremented by one unit.

Answer

A mutex is used for mutual exclusion, while a semaphore is used for signaling.

Answer

A semaphore can be used for multiple threads, while a mutex can only be used for two threads.

Question 52

Which deadlock prevention strategy can lead to decreased system performance by potentially delaying the execution of processes?

Accepted Answer

Resource ordering

Answer

Rollback

Answer

Resource pre-allocation

Answer

Deadlock detection