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Unit 3 - Practice Quiz

CSE316

1 What is a 'Race Condition' in Operating Systems?

A. A situation where several processes access and manipulate the same data concurrently and the outcome depends on the order of execution
B. A condition where the operating system runs faster than the hardware
C. A situation where processes compete for the CPU scheduler
D. A condition where a process races to finish before the time quantum expires

2 Which of the following is NOT a requirement for a solution to the Critical Section Problem?

A. Mutual Exclusion
B. Progress
C. Bounded Waiting
D. processor Speed

3 What does 'Mutual Exclusion' imply in the context of the Critical Section Problem?

A. If a process is executing in its critical section, then no other processes can be executing in their critical sections
B. All processes must execute their critical sections simultaneously
C. Processes must share the same memory address space
D. The operating system excludes processes from using the CPU

4 What is a Semaphore?

A. A hardware instruction
B. A protected integer variable that can only be accessed via two atomic operations
C. A queue of processes waiting for I/O
D. A specialized CPU register

5 In a Semaphore, what does the 'wait' (or P) operation do?

A. Increments the semaphore value
B. Decrements the semaphore value
C. Sets the semaphore value to zero
D. Reads the semaphore value without changing it

6 What is the main disadvantage of a Spinlock?

A. It causes context switching
B. It requires busy waiting, wasting CPU cycles
C. It is difficult to implement
D. It cannot handle multiple processes

7 A binary semaphore is also known as a:

A. Monitor
B. Mutex lock
C. Counting semaphore
D. Spinlock

8 Which hardware instruction is commonly used to implement mutual exclusion?

A. LoadAndStore
B. TestAndSet
C. JumpAndLink
D. PushAndPop

9 What is the 'Bounded Waiting' requirement?

A. A process must wait for a fixed amount of time
B. There exists a bound on the number of times other processes are allowed to enter their critical sections after a process has made a request to enter its critical section
C. The critical section size must be bounded
D. Processes must wait in a queue indefinitely

10 In the Producer-Consumer problem using a bounded buffer, when does the Producer wait?

A. When the buffer is empty
B. When the buffer is full
C. When the Consumer is sleeping
D. When the mutex is unlocked

11 Which of the following is a high-level synchronization construct that ensures mutual exclusion automatically?

A. Semaphore
B. Monitor
C. Spinlock
D. Peterson's Solution

12 In the Dining Philosophers problem, deadlock occurs if:

A. All philosophers pick up their left chopstick simultaneously
B. One philosopher picks up both chopsticks
C. Philosophers eat sequentially
D. The philosophers do not speak to each other

13 What is Peterson's Solution used for?

A. Managing memory fragmentation
B. Solving the Critical Section problem for two processes
C. Scheduling threads
D. Handling hardware interrupts

14 In Peterson's solution, which variables are shared between processes?

A. semaphore and mutex
B. turn and flag
C. lock and key
D. start and finish

15 What problem is the Readers-Writers problem primarily concerned with?

A. Allowing multiple writers to write simultaneously
B. Ensuring exclusive access for writers while allowing multiple concurrent readers
C. Preventing readers from reading shared data
D. Synchronizing two writers only

16 What happens to threads that call 'wait' on a Condition Variable in a Monitor?

A. They continue executing
B. They are suspended and placed in a waiting queue
C. They are terminated
D. They enter a busy-wait loop

17 Which of the following is NOT shared by threads of the same process?

A. Code section
B. Global variables
C. Open files
D. Program Counter and Stack

18 What is a Heavyweight Process compared to a Thread?

A. A process with a single thread of control
B. A kernel-level thread
C. A thread with a large stack
D. A process with no memory

19 Which multithreading model maps many user-level threads to a single kernel thread?

A. One-to-One Model
B. Many-to-One Model
C. Many-to-Many Model
D. Two-Level Model

20 What is a limitation of the Many-to-One multithreading model?

A. It consumes too many kernel resources
B. The entire process blocks if one thread makes a blocking system call
C. It does not support user-level threads
D. It is too complex to implement

21 Which multithreading model provides more concurrency than Many-to-One but doesn't require a kernel thread for every user thread?

A. One-to-One Model
B. Many-to-Many Model
C. Single Thread Model
D. Independent Model

22 What is 'Scheduler Activation'?

A. A mechanism for communication between the user-thread library and the kernel
B. A hardware interrupt that starts the scheduler
C. A signal to kill a process
D. The process of activating the CPU clock

23 Which standard defines the API for thread creation and synchronization (Pthreads)?

A. POSIX
B. Win32
C. Java
D. ANSI

24 What is the function of pthread_join()?

A. Creates a new thread
B. Terminates a thread
C. Waits for a specific thread to terminate
D. Unlocks a mutex

25 A Precedence Graph is a directed acyclic graph used to:

A. Visualize the memory usage of a process
B. Describe the execution dependencies among concurrent processes
C. Map virtual memory to physical memory
D. Show the hierarchy of file systems

26 What defines 'Co-operating Processes'?

A. Processes that do not share data
B. Processes that can affect or be affected by other executing processes
C. Processes running on different computers
D. Processes that are completely independent

27 In the context of process hierarchy, what system call is typically used in Unix/Linux to create a new process?

A. create()
B. new()
C. fork()
D. spawn()

28 If a Semaphore S has a value of 10, and 5 P (wait) operations and 3 V (signal) operations are performed, what is the final value of S?

A. 12
B. 8
C. 2
D. 10

29 What is the 'Bakery Algorithm' designed to solve?

A. The Producer-Consumer problem
B. The Critical Section problem for N processes
C. Deadlock recovery
D. Memory allocation

30 Which of the following is true regarding User-Level Threads (ULT)?

A. The kernel is aware of all ULTs
B. Context switching is faster than Kernel-Level Threads
C. They require hardware support
D. They cannot run on any OS

31 In the One-to-One multithreading model, what is the main drawback?

A. Creating a user thread requires creating a corresponding kernel thread, which creates overhead
B. It blocks the whole process on I/O
C. It does not support multiprocessors
D. It is not standard

32 What is an 'Upcall' in the context of Scheduler Activations?

A. A call from a user thread to the kernel
B. A notification from the kernel to the thread library
C. increasing the priority of a thread
D. Uploading data to the cloud

33 Which synchronization primitive is typically used to solve the Reader-Writer problem to prevent writer starvation?

A. Semaphores with a priority queue
B. Spinlocks
C. TestAndSet
D. Disable Interrupts

34 What is 'Priority Inversion'?

A. A lower priority process holds a lock needed by a higher priority process
B. The scheduler runs processes in reverse order
C. Assigning priority 0 to the most important process
D. Inverting the bits of the semaphore

35 How does the 'Swap' hardware instruction assist in synchronization?

A. It swaps the content of two memory words atomically
B. It moves a process to swap space
C. It switches between user and kernel mode
D. It changes the process ID

36 In a Monitor, if process P executes x.signal() and process Q was waiting on x, and Q immediately executes while P waits, this strategy is called:

A. Signal and Wait (Hoare semantics)
B. Signal and Continue (Mesa semantics)
C. Broadcast
D. Busy Waiting

37 Which component allows a thread to have its own copy of data?

A. TLS (Thread Local Storage)
B. Global Heap
C. Shared Memory
D. Semaphore

38 The problem where a producer tries to put an item into a full buffer is handled by:

A. Putting the producer to sleep
B. Discarding the item
C. Overwriting the oldest item
D. Killing the consumer

39 Why is disabling interrupts not a viable solution for mutual exclusion in multiprocessor systems?

A. It is too slow
B. It only disables interrupts on one processor, not all
C. It causes the OS to crash
D. It requires too much power

40 What is 'Busy Waiting'?

A. A process waiting in a queue
B. A process repeatedly checking a condition until it becomes true
C. A process waiting for I/O
D. The CPU executing a NOP instruction

41 Which of the following is a valid state for a Java thread?

A. RUNNING
B. BLOCKED
C. WAITING
D. All of the above

42 In the context of threads, what is 'cancellation'?

A. Terminating a thread before it has completed
B. Deleting the thread library
C. Stopping the CPU
D. Removing a semaphore

43 Deferred cancellation of a thread means:

A. The thread is cancelled immediately
B. The thread checks periodically if it should terminate
C. The thread is cancelled after 1 minute
D. The thread cancels the parent process

44 A solution to the Dining Philosophers problem using a monitor restricts a philosopher to pick up chopsticks only if:

A. Both neighbors are not eating
B. The left neighbor is eating
C. The right neighbor is eating
D. They have a ticket

45 Which type of semaphore can take any non-negative integer value?

A. Binary Semaphore
B. Counting Semaphore
C. Mutex
D. Spinlock

46 What defines a 'Thread Safe' function?

A. It runs very fast
B. It can be called from multiple threads simultaneously without producing incorrect results
C. It uses no memory
D. It creates a new thread

47 In the 'Sleeping Barber' problem (a variation of producer-consumer), what happens if the customer arrives and the waiting room is full?

A. The customer waits outside
B. The customer leaves
C. The customer wakes the barber
D. The barber cuts two heads at once

48 What is the benefit of the 'Grand Central Dispatch' (GCD) technology in macOS/iOS?

A. It increases clock speed
B. It manages thread pools and scheduling automatically
C. It replaces the kernel
D. It creates infinite threads

49 Concurrency vs Parallelism: Which statement is true?

A. They are exactly the same
B. Parallelism requires multiple processors/cores, Concurrency does not
C. Concurrency requires multiple processors
D. Parallelism is software only

50 What is the primary purpose of a Condition Variable?

A. To store the process ID
B. To allow threads to wait for a specific condition to become true
C. To increment a counter
D. To lock a file