Test Bank Docx Ch4 Threads & Concurrency

Chapter 4

Multiple Choice

1. Which of the following items are shared across multiple threads belonging to the same process?

A) code, data, files

B) registers

C) stack

D) all of the above

Feedback: 4.1

Difficulty: Easy

2. In a multithreaded server architecture, which of the following is used to service a new user request?

A) a new created thread

B) a new created process

C) the same process for prior users

D) none of the above

Feedback: 4.1.1

Difficulty: Medium

3. Which of the following benefits go to multithreaded programming?

A) responsiveness

B) resource sharing

C) economy

D) scalability

E) all of the above

Feedback: 4.1.2

Difficulty: Easy

4. Which of the following refers to the capability to allow multiple tasks make progress on a single processor system?

A) concurrency

B) parallelism

C) data parallelism

D) task parallelism

Feedback: 4.2

Difficulty: Medium

5. ___________ is a formula that identifies potential performance gains from adding additional computing cores to an application that has a parallel and serial component.

A) Task parallelism

B) Data parallelism

C) Data splitting

D) Amdahl's Law

Feedback: 4.2.1

Difficulty: Medium

6. _____ is not considered a challenge when designing applications for multicore systems.

A) Deciding which activities can be run in parallel

B) Ensuring there is a sufficient number of cores

C) Determining if data can be separated so that it is accessed on separate cores

D) Identifying data dependencies between tasks.

Feedback: 4.2.1

Difficulty: Medium

7. Which of the following models are possible for the relationship between the user threads and kernel threads?

A) many-to-one model

B) one-to-one model

C) many-to-many model

D) two-level model

E) all of the above

Feedback: 4.3

Difficulty: Easy

8. ____ is a thread library for Solaris that maps many user-level threads to one kernel thread.

A) Pthreads

B) Green threads

C) Sthreads

D) Java threads

Feedback: 4.3.1

Difficulty: Medium

9. The _____ model maps each user-level thread to one kernel thread.

A) many-to-many

B) two-level

C) one-to-one

D) many-to-one

Feedback: 4.3.2

Difficulty: Easy

10. The _____ model multiplexes many user-level threads to a smaller or equal number of kernel threads.

A) many-to-many

B) two-level

C) one-to-one

D) many-to-one

Feedback: 4.3.3

Difficulty: Easy

11. Which of the following is a function that can be provided by Pthreads API for constructing a multithreaded program?

A) pthread attr init

B) pthread_create

C) pthread_join

D) all of the above

Feedback: 4.4.1

Difficulty: Easy

12. In Pthreads, a parent uses the pthread_join() function to wait for its child thread to complete. What is the equivalent function in Win32?

A) win32_join()

B) wait()

C) WaitForSingleObject()

D) join()

Section 4.4.2

Difficulty: Medium

13. Which of the following statements regarding threads is false?

A) Sharing is automatically provided in Java threads.

B) Both Pthreads and Win32 threads share global data.

C) The start() method actually creates a thread in the Java virtual machine.

D) The Java method join() provides similar functionality as the WaitForSingleObject in Win32.

Feedback: 4.4.3

Difficulty: Medium

14. The most common technique for writing multithreaded Java programs is _____.

A) extending the Thread class and overriding the run() method

B) implementing the Runnable interface and defining its run() method

C) designing your own Thread class

D) using the CreateThread() function

Feedback: 4.4.3

Difficulty: Easy

15. Which of the following is a method for implicit threading?

A) thread pools

B) OpenMP

C) grand central dispatch

D) all of the above

Feedback: 4.5

Difficulty: Easy

16. Which of the following implicit threading methodology involves dispatch queues?

A) thread pools

B) OpenMP

C) grand central dispatch

D) all of the above

Feedback: 4.5.4

Difficulty: Easy

17. Which of the following is an asynchronous signal?

A) illegal memory access

B) division by zero

C) terminating a process with specific keystrokes

D) none of the above

Feedback: 4.6.2

Difficulty: Medium

18. Which of the following is a synchronous signal?

A) illegal memory access

B) terminating a process with specific keystrokes

C) having a timer expire

D) none of the above

Feedback: 4.6.2

Difficulty: Medium

19. Which of the following options exist to deliver signals in multithreaded program?

A) deliver the signal to the thread to which the signal applies

B) deliver the signal to every thread in the process

C) deliver the signal to certain threads in the process

D) assign a specific thread to receive all signals for the process

E) all of the above

Feedback: 4.6.2

Difficulty: Easy

20. Which of the following options to deliver signals in multithreaded program should be applied to an asynchronous signal that terminates a process (<control><C>, for example)?

A) deliver the signal to the thread to which the signal applies

B) deliver the signal to every thread in the process

C) deliver the signal to certain threads in the process

D) assign a specific thread to receive all signals for the process

E) all of the above

Feedback: 4.6.2

Difficulty: Medium

21. Which of the following options to deliver signals in multithreaded program should be applied to a synchronous signal?

A) deliver the signal to the thread to which the signal applies

B) deliver the signal to every thread in the process

C) deliver the signal to certain threads in the process

D) assign a specific thread to receive all signals for the process

E) all of the above

Feedback: 4.6.2

Difficulty: Medium

22. Signals can be emulated in windows through ____.

A) asynchronous procedure calls

B) local procedure calls

C) remote procedure calls

D) none of the above

Feedback: 4.6.2

Difficulty: Medium

23. Which of the following cancellation modes are supported by Pthreads?

A) off mode

B) deferred mode

C) asynchronous mode

D) all of the above

Feedback: 4.6.3

Difficulty: Easy

24. Which of the following cancellation modes is the default cancellation type?

A) off mode

B) deferred mode

C) asynchronous mode

D) all of the above

Feedback: 4.6.3

Difficulty: Easy

25. Which of the following Pthread function is used to respond to a cancellation request using deferred cancellation?

A) pthread attr init

B) pthread_create

C) pthread_join

D) pthread_testcancel

Feedback: 4.6.3

Difficulty: Medium

26. To associate each thread created using an implicit technique such as a thread pool, with its unique transaction identifier, we could use ____?

A) global variable

B) local variable

C) static data

D) thread-local storage

Feedback: 4.6.4

Difficulty: Easy

27. LWP is ____.

A) short for lightweight processor

B) placed between system and kernel threads

C) placed between user and kernel threads

D) common in systems implementing one-to-one multithreading models

Feedback: 4.6.5

Difficulty: Easy

28. In multithreaded programs, the kernel informs an application about certain events using a procedure known as a(n) ____.

A) signal

B) upcall

C) event handler

D) pool

Feedback: 4.6.5

Difficulty: Medium

29. Which are included in the context of a thread?

A) register set

B) stacks

C) private storage area

D) all of the above

Feedback: 4.7.1

Difficulty: Easy

30. Which of the following information is shared when the flag CLONE_VM is set up?

A) file-system information

B) memory space

C) signal handlers

D) set of open files

Feedback: 4.7.2

Difficulty: Easy

Essay Questions

1. Why should a web server not run as a single-threaded process?

Feedback: 4.1.1

Difficulty: Medium

2. List the four major categories of the benefits of multithreaded programming. Briefly explain each.

Feedback: 4.1.2

Difficulty: Hard

3. Distinguish between parallelism and concurrency.

Feedback: 4.2

Difficulty: Medium

4. Multicore systems present certain challenges for multithreaded programming. Briefly describe these challenges.

Feedback: 4.2.1

Difficulty: Difficult

5. Distinguish between data and task parallelism.

And: Data parallelism involves distributing subsets of the same data across multiple computing cores and performing the same operation on each core. Task parallelism involves distributing tasks across the different computing cores where each task is performing a unique operation.

Feedback: 4.2.2

Difficulty: Hard

6. What are the two different ways in which a thread library could be implemented?

Feedback: 4.4

Difficulty: Medium

7. What are the general components of a thread in Windows?

Feedback: 4.4.2

Difficulty: Medium

8. Describe two techniques for creating Thread objects in Java.

Feedback: 4.4.3

Difficulty: Medium

9. In Java, what two things does calling the start() method for a new Thread object accomplish?

Feedback: 4.4.3

Difficulty: Medium

10. What is a thread pool and why is it used?

Feedback: 4.5.1

Difficulty: Medium

11. Describe how OpenMP is a form of implicit threading.

Feedback: 4.5.2

Difficulty: Hard

12. Describe how Grand Central Dispatch is a form of implicit threading.

Feedback: 4.5.3

Difficulty: Hard

13. Some UNIX systems have two versions of fork(). Describe the function of each version, as well as how to decide which version to use.

Feedback: 4.6.1

Difficulty: Hard

14. How can deferred cancellation ensure that thread termination occurs in an orderly manner as compared to asynchronous cancellation?

Feedback: 4.6.3

Difficulty: Medium

15. Describe the difference between the fork() and clone() Linux system calls.

Feedback: 4.7.2

Difficulty: Medium

True/False Questions

1. Virtually all contemporary operating systems support kernel threads.

Feedback: 4.1.1

Difficulty: Easy

2. Amdahl's Law describes performance gains for applications with both a serial and parallel component.

Feedback: 4.2

Difficulty: Medium

3. Concurrency is inherently equivalent to parallelism.

Feedback: 4.2

Difficulty: Medium

4. Parallelism can be achieved on single-processor systems.

Feedback: 4.2

Difficulty: Medium

5. Task parallelism distributes threads and data across multiple computing cores.

Feedback: 4.2.2

Difficulty: Difficult

6. One-to-one model provides more concurrency than the many-to-one model by allowing another thread to run when a thread makes a blocking system call.

Feedback: 4.3.2

Difficulty: Easy

7. In Java, data shared between threads is simply declared globally.

Feedback: 4.4.3

Difficulty: Medium

8. The trend in developing parallel applications is to use implicit threading.

Feedback: 4.5

Difficulty: Medium

9. The single benefit of a thread pool is to control the number of threads.

Feedback: 4.5.1

Difficulty: Easy

10. OpenMP only works for C, C++, and Fortran programs.

Feedback 4.5.2:

Difficulty: Medium

11. Grand Central Dispatch requires multiple threads.

Feedback: 4.5.3

Difficulty: Medium

12. The default signal handler can be overridden by a user-defined signal handler.

Feedback: 4.6.2

Difficulty: Easy

13. Deferred cancellation is preferred over asynchronous cancellation.

Feedback: 4.6.3

Difficulty: Easy

14. Thread-local storage is inherently equivalent to local variables.

Feedback: 4.6.4

Difficulty: Medium

15. When fork() is invoked, it is passed a set of flags that determine how much sharing is to take place between the parent and child tasks.

Feedback: 4.7.2

Difficulty: Medium