Question 1

If a thread attempts a P operation when a counting semaphore has been decremented to zero, ________.

Accepted Answer

A)   the thread obtains a resource from the pool and decrements the semaphore to -1
B)   the thread obtains a resource from the pool and the semaphore remains equal to 0
C)   the thread must wait until a resource is returned to the pool by a V operation
D)   the thread returns a resource to the pool and increments the semaphore to 1E) All of the above
F) C) and D)

Question 2

Code inside a critical section should ________.

Accepted Answer

A)   access shared, modifiable data
B)   run as quickly as possible
C)   prevent the possibility of infinite loops
D)   all of the aboveE) A) and B)
F) C) and D)

Question 3

Semaphore operations can be implemented in the kernel of a multiprocessor system by:

Accepted Answer

A)   giving one processor the job of controlling the ready list.
B)   controlling access (via busy waiting)  to a shared ready list.
C)   both a and b
D)   none of the aboveE) A) and C)
F) A) and B)

Question 4

An example of a producer/consumer relationship is ________.

Accepted Answer

A)   an application that copies data from a fixed-size buffer to a CD-RW
B)   a word processor that sends data to a buffer to be printed
C)   both a and b
D)   none of the aboveE) C) and D)
F) All of the above

Question 5

What happens when a thread calls P( S )  when it wants to enter its critical section, where S is a binary semaphore set to 1?

Accepted Answer

A)   The thread is allowed to enter its critical section and S is decremented.
B)   The thread is blocked and added to a queue of waiting threads.
C)   The semaphore is set to 2.
D)   none of the aboveE) B) and C)
F) B) and D)

Question 6

Which of the following statements about critical sections is false?

Accepted Answer

A)   Only one thread at a time can execute the instructions in its critical section for a particular resource.
B)   If one thread is already in its critical section, another thread must wait for the executing thread to exit its critical section before continuing.
C)   Once a thread has exited its critical section, a waiting thread may enter its critical section.
D)   All threads must wait whenever any critical section is occupied.E) A) and C)
F) A) and D) D

Question 7

In Java, the sleep method call must appear in part of a ________ statement because it might throw an exception indicating that the thread was interrupted before its sleep time expired.

Accepted Answer

A)   if...else
B)   do...while
C)   try...catch
D)   switchE) None of the above
F) C) and D)

Question 8

Threads that operate independently of one another but must occasionally interact to perform cooperative tasks are said to execute ________.

Accepted Answer

A)   synchronously
B)   in parallel
C)   asynchronously
D)   simultaneouslyE) None of the above
F) A) and C)

Question 9

Which of the following statements about semaphores is true?

Accepted Answer

A)   P and V operations should be indivisible operations.
B)   If several threads attempt a P( S )  operation simultaneously, only one thread should be allowed to proceed.
C)   A semaphore implementation should guarantee that threads do not suffer indefinite postponement.
D)   all of the aboveE) A) and B)
F) A) and C)

Question 10

________ restricts access to a shared variable to only one thread at any given time.

Accepted Answer

A)   asynchronism
B)   serialization
C)   protection
D)   mutual exclusionE) All of the above
F) A) and B)

Question 11

Which of the following mutual exclusion algorithms require instructions to be executed atomically?

Accepted Answer

A)   Dekker's algorithm
B)   Peterson's algorithm
C)   Lamport's algorithm
D)   both a and bE) All of the above
F) A) and D)

Question 12

Semaphores can be used for each of the following purposes except:

Accepted Answer

A)   to protect access to a critical section
B)   to notify the process that an event has occurred
C)   to prevent shared variables from getting corrupted
D)   to synchronize two or more concurrent threadsE) A) and D)
F) B) and C) B

Question 13

A thread that uses processor cycles to continually test a condition before entering its critical section is said to be ________.

Accepted Answer

A)   lockstep synchronized
B)   deadlocked
C)   busy waiting
D)   indefinitely postponedE) C) and D)
F) B) and C)

Question 14

The test-and-set instruction ________.

Accepted Answer

A)   prevents deadlock
B)   prevents indefinite postponement
C)   eliminates the possibility that a thread is preempted between reading a value from a memory location and writing a new value to the memory location
D)   none of the aboveE) A) and B)
F) None of the above

Question 15

A ________ is a variable that governs access to critical sections.

Accepted Answer

A)   primitive
B)   lock
C)   controller
D)   flagE) B) and D)
F) B) and C)

Question 16

Which property of mutual exclusion primitives is inappropriate for multiprocessor systems?

Accepted Answer

A)   The solution is implemented purely in software on a machine without specially designed mutual exclusion machine-language instructions.
B)   No assumption can be made about the relative speeds of asynchronous concurrent threads.
C)   A thread that is executing instructions outside its critical section cannot prevent any other threads from entering their critical sections.
D)   A thread must not be indefinitely postponed from entering its critical section.E) A) and B)
F) A) and C) A

Question 17

Lamport's Bakery Algorithm does not require ________.

Accepted Answer

A)   a large number of shared variables
B)   complicated loops
C)   that any operations occur atomically
D)   all of the aboveE) A) and B)
F) C) and D)

Question 18

In Java, Object method notify transitions a thread from the ________ state to the ________ state.

Accepted Answer

A)   waiting, ready
B)   blocked, waiting
C)   running, waiting
D)   ready, runningE) A) and B)
F) None of the above

Question 19

Disabling interrupts ________.

Accepted Answer

A)   is a viable solution for mutual exclusion in a multiprocessor system
B)   on a uniprocessor system could result in an infinite loop causing the system to hang
C)   typically prevents a thread from being preempted while accessing shared data
D)   both b and cE) A) and B)
F) All of the above

Question 20

________ occurs when an infinite loop prevents progress in a multithreaded application.

Accepted Answer

A)   Lockstep synchronization
B)   Deadlock
C)   Busy waiting
D)   Indefinite postponementE) B) and D)
F) None of the above

Exam 5: Exploring Thread Synchronization and Mutual Exclusion in Java

If a thread attempts a P operation when a counting semaphore has been decremented to zero, ________.

Correct AnswerverifiedShow Answer

Code inside a critical section should ________.

Correct AnswerverifiedShow Answer

Semaphore operations can be implemented in the kernel of a multiprocessor system by:

Correct AnswerverifiedShow Answer

An example of a producer/consumer relationship is ________.

Correct AnswerverifiedShow Answer

What happens when a thread calls P( S ) when it wants to enter its critical section, where S is a binary semaphore set to 1?

Correct AnswerverifiedShow Answer

Which of the following statements about critical sections is false?

Correct AnswerverifiedD

In Java, the sleep method call must appear in part of a ________ statement because it might throw an exception indicating that the thread was interrupted before its sleep time expired.

Correct AnswerverifiedShow Answer

Threads that operate independently of one another but must occasionally interact to perform cooperative tasks are said to execute ________.

Correct AnswerverifiedShow Answer

Which of the following statements about semaphores is true?

Correct AnswerverifiedShow Answer

________ restricts access to a shared variable to only one thread at any given time.

Correct AnswerverifiedShow Answer

Which of the following mutual exclusion algorithms require instructions to be executed atomically?

Correct AnswerverifiedShow Answer

Semaphores can be used for each of the following purposes except:

Correct AnswerverifiedB

A thread that uses processor cycles to continually test a condition before entering its critical section is said to be ________.

Correct AnswerverifiedShow Answer

The test-and-set instruction ________.

Correct AnswerverifiedShow Answer

A ________ is a variable that governs access to critical sections.

Correct AnswerverifiedShow Answer

Which property of mutual exclusion primitives is inappropriate for multiprocessor systems?

Correct AnswerverifiedA

Lamport's Bakery Algorithm does not require ________.

Correct AnswerverifiedShow Answer

In Java, Object method notify transitions a thread from the ________ state to the ________ state.

Correct AnswerverifiedShow Answer

Disabling interrupts ________.

Correct AnswerverifiedShow Answer

________ occurs when an infinite loop prevents progress in a multithreaded application.

Correct AnswerverifiedShow Answer

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D

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B

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A

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In Java, Object method notify transitions a thread from the state to the state.

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