Deck 4: Exploring Semaphores and Multithreading in Operating Systems

Question 1

In the 1970s and 1980s, what was an early roadblock to concurrent programming?

A) Early operating systems did not allow several programs to execute concurrently.
B) Early computers were too slow to permit concurrency.
C) Early programming languages did not include primitives enabling programmers to write concurrent programs.
D) all of the above

Answer 1

Early programming languages did not include primitives enabling programmers to write concurrent programs.

Question 2

________, ________ and ________ are general-purpose programming languages that directly support concurrency through multithreading.

A) C, C++, Python
B) Java, C#, Visual Basic .NET
C) C++, Visual C++ .NET, Python
D) Java, C, C#

Answer 2

Java, C#, Visual Basic .NET

Question 3

Which of the following statements about threads is false?

A) Threads possess a subset of the resources contained in a process.
B) Threads can be dispatched to a processor.
C) Threads cannot execute instructions independent of other processes.
D) A process's threads can cooperate to attain a common goal efficiently.

Answer 3

Threads cannot execute instructions independent of other processes.

Question 4

The POSIX specification provides the ________ standard for developing portable multithreaded applications.

A) Win32 threads
B) Pthreads
C) C-threads
D) portable threads

Question 5

Multithreading is important because it can ________.

A) facilitate software design and promote good programming practices
B) improve performance and scalability
C) facilitate cooperation/synchronization of activities
D) all of the above

Question 6

Which of the following applications can benefit from multithreading?

A) a simple text editor
B) a Web server
C) an image viewer
D) both a and c

Question 7

A thread enters the waiting state when ________.

A) it momentarily has no work to perform
B) it cannot perform further operations until it receives a signal from another thread
C) it must wait for the completion of an I/O request
D) all of the above

Question 8

A(n) ________ thread can enter the sleeping state for a specified period of time, after which it enters to the ________ state.

A) ready, running
B) running, ready
C) running, blocked
D) waiting, ready

Question 9

Many operating systems require ________ instructions to share resources than they do to initialize them, so in these systems, thread creation is ________ than process creation.

A) more, faster
B) more, slower
C) fewer, faster
D) fewer, slower

Question 10

Which of the following statements about thread operations is true?

A) When a thread joins another thread, the former does not execute until the latter terminates.
B) Thread cancellation always terminates the target thread immediately.
C) A thread can mask an abort signal.
D) A process can continue execution after its primary thread exits.

Question 11

User-level thread implementations are also called ________ thread mappings.

A) one-to-one
B) one-to-many
C) many-to-one
D) many-to-many

Question 12

Threads in user space can be more appropriate than kernel threads because ________.

A) user-level threads do not require the operating system to support threads.
B) application developers can tune the threading library's scheduling algorithm to meet the needs of specific applications.
C) user-level threads do not invoke the kernel for synchronization, which can reduce overhead.
D) all of the above

Question 13

Kernel-level threads are often described as ________ thread mappings.

A) one-to-one
B) one-to-many
C) many-to-one
D) many-to-many

Question 14

Which of the following statements about kernel-level threads is false?

A) The kernel can manage each of a process's threads individually.
B) A process that uses kernel-level threads often can adjust the level of service each thread receives from the operating system.
C) Software that employs kernel-level threads often is more portable than software that employs user-level threads.
D) Kernel-level threads require the operating system to manage all threads in the system.

Question 15

The amount of overhead incurred by many-to-many thread mappings that implement thread pooling is _________ the amount of overhead incurred by one-to-one mappings.

A) greater than
B) less than
C) the same as
D) unrelated to

Question 16

Which of the following statements about scheduler activations is false?

A) A scheduler activation executes the process's user-level threading-library initialization code.
B) A scheduler activation is a user thread that can notify a kernel-level threading library of events.
C) A scheduler activation creates threads and requests additional processors for its threads, if necessary.
D) An additional scheduler activation is created for each processor allocated to a process.

Question 17

In which of the following events would the operating system send a synchronous signal?

A) when an I/O operation completes
B) when the operating system suspends a process
C) when a process or thread performs an illegal memory operation
D) when the operating system continues a process

Question 18

According to the POSIX specification, processes send signals by specifying a ________.

A) thread identifier
B) process identifier
C) pointer to a process control block
D) any of the above are allowed

Question 19

What could cause a thread to terminate prematurely?

A) an exception (such an illegal memory reference)
B) a cancellation signal from a process or thread
C) both a and b
D) neither a nor b

Question 20

A POSIX thread that defers cancellation ________.

A) can be terminated at any point during its execution
B) will not be cancelled until it explicitly checks for a cancellation request
C) is not notified when a cancellation operation has been requested
D) none of the above

Question 21

According to the POSIX threading API, processor registers, a stack and a signal mask are ________.

A) maintained individually for each thread in a process
B) shared between all threads in a process
C) shared between some threads in a process
D) none of the above

Question 22

In Linux, what is the difference between the fork and clone system calls?

A) clone accepts arguments that specify which resources to share with the spawned process.
B) Linux responds to the clone system call by creating a new task that contains a copy of all of its parent's resources.
C) clone creates a copy of the calling task, and the copy becomes the parent of the task that issued the clone system call.
D) fork and clone spawn child processes in exactly the same way.

Question 23

In Linux, a process in the ________ state has been terminated but has not yet been removed from the system.

A) sleeping
B) blocked
C) zombie
D) dead

Question 24

Which of the following statements about Windows XP threads is false?

A) Threads are the primary unit of execution in Windows XP.
B) Threads execute a portion of a process's code in the process's context.
C) Each thread contains its own execution context.
D) Each thread belonging to a process is assigned a unique virtual address space.

Question 25

In Windows XP, a fiber is scheduled for execution ________.

A) by the thread that creates it
B) by the operating system's scheduler
C) by the process
D) none of the above

Question 26

The size of a thread pool in Windows XP is ________.

A) constant and specified by the programmer for each process
B) constant for all processes on a system
C) variable, modified by the system in response to the volume of requests
D) all of the above are possible

Question 27

In Windows XP, a thread enters the ________ state when the thread's requested data is currently unavailable, but the thread is otherwise ready to execute.

A) standby
B) transition
C) waiting
D) unknown

Question 28

In Java, the ________ method of the Thread class contains the code that performs the "real work" of a thread.

A) run
B) start
C) go
D) main

Question 29

Java implements thread signaling using the ________ method of the Thread class.

A) alert
B) signal
C) interrupt
D) wake