Deck 5: Concurrency: Mutual Exclusion and Synchronization

Question 1

Atomicity guarantees isolation from concurrent processes.

Answer 1

True

Question 2

It is possible for one process to lock the mutex and for another process to unlock it.

Answer 2

False

Question 3

Two or more processes can cooperate by means of simple signals, such that a process can be forced to stop at a specified place until it has received a specific signal.

Answer 3

True

Question 4

When processes cooperate by communication, the various processes participate in a common effort that links all of the processes.

Question 5

Race condition is a situation in which two or more processes continuously change their states in response to changes in the other process(es) without doing any useful work.

Question 6

A semaphore that does not specify the order in which processes are removed from the queue is a _________ semaphore.

A) weak
B) general
C) strong
D) binary

Question 7

The management of multiple processes within a uniprocessor system is __________ .

A) multiprogramming
B) structured applications
C) distributed processing
D) multiprocessing

Question 8

The case of cooperation by sharing covers processes that interact with other processes without being explicitly aware of them.

Question 9

Processes need to be synchronized to enforce mutual exclusion.

Question 10

As an extension of the principles of modular design and structured programming, some applications can be effectively programmed as a set of concurrent processes.

Question 11

The central themes of operating system design are all concerned with the management of processes and threads.

Question 12

A situation in which a runnable process is overlooked indefinitely by the scheduler, although it is able to proceed, is __________ .

A) mutual exclusion
B) deadlock
C) starvation
D) livelock

Question 13

It is possible in a single-processor system to not only interleave the execution of multiple processes but also to overlap them.

Question 14

One of the most common problems faced in concurrent processing is the producer/consumer problem.

Question 15

A process that is waiting for access to a critical section does not consume processor time.

Question 16

The functioning of a process, and the output it produces, must be independent of the speed at which its execution is carried out relative to the speed of other concurrent processes.

Question 17

Concurrent processes do not come into conflict with each other when they are competing for the use of the same resource.

Question 18

The requirement that when one process is in a critical section that accesses shared resources, no other process may be in a critical section that accesses any of those shared resources is _________ .

A) critical section
B) livelock
C) mutual exclusion
D) atomic operation

Question 19

A means for two processes to exchange information is with the use of ___________ .

A) spinlocks
B) event flags
C) condition variables
D) messages

Question 20

The sharing of main memory among processes is useful to permit efficient and close interaction among processes because such sharing does not lead to any problems.

Question 21

__________ are memory words used as a synchronization mechanism.

A) Semaphores
B) Event flags
C) Counting semaphores
D) Mailboxes

Question 22

In the case of __________ , processes are sharing resources without being aware of the other processes.

Question 23

A situation in which two or more processes are unable to proceed because each is waiting for one of the others to do something is a __________ .

Question 24

__________ is a function or action implemented as a sequence of one or more instructions that appears to be indivisible; no other process can see an intermediate state or interrupt the operations.

Question 25

A _________ is a data type that is used to block a process or thread until a particular condition is true.

A) deadlock
B) general semaphore
C) condition variable
D) mutex

Question 26

A __________ is a programming language construct that encapsulates variables, access procedures, and initialization code within an abstract data type.

Question 27

A _________ occurs when multiple processes or threads read and write data items so that the final result depends on the order of execution of instructions in the multiple processes.

A) atomic operation
B) race condition
C) livelock
D) deadlock

Question 28

_________ arises in three different contexts: multiple applications, structured applications, and operating system structure.

Question 29

Probably the most useful combination, __________ allows a process to send one or more messages to a variety of destinations as quickly as possible.

A) blocking send, blocking receive
B) nonblocking send, blocking receive
C) nonblocking send, nonblocking receive
D) blocking send, nonblocking receive

Question 30

A __________ relationship allows multiple server processes to provide concurrent service to multiple clients.

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

Question 31

The term _________ refers to a technique in which a process can do nothing until it gets permission to enter its critical section but continues to execute an instruction or set of instructions that tests the appropriate variable to gain entrance.

A) spin waiting
B) general semaphore
C) critical resource
D) message passing

Question 32

A ___________ is a semaphore that takes on only the values of 0 and 1.

Question 33

A _________ is an integer value used for signaling among processes.

A) semaphore
B) message
C) mutex
D) atomic operation

Question 34

In the case of competing processes three control problems must be faced: mutual exclusion, deadlock, and __________ .

Question 35

_________ is a section of code within a process that requires access to shared resources and that must not be executed while another process is in a corresponding section of code.

Question 36

A semaphore whose definition includes the policy that the process that has been blocked the longest is released from the queue first is called a __________ semaphore.

A) general
B) strong
C) weak
D) counting

Question 37

_________ was invented to allow processing time to be dynamically shared among a number of active applications.

Question 38

A situation in which multiple threads or processes read and write a shared data item and the final result depends on the relative timing of their execution is a __________ .

Question 39

The _________ is a programming language construct that provides equivalent functionality to that of semaphores and is easier to control.

A) atomic operation
B) coroutine
C) critical section
D) monitor

Question 40

_________ is when the sequence of instruction is guaranteed to execute as a group, or not execute at all, having no visible effect on system state.

A) Critical section
B) Mutual exclusion
C) Atomic operation
D) Starvation

Question 41

A _________ is a mutual exclusion mechanism in which a process executes in an infinite loop waiting for the value of a lock variable to indicate availability.

Question 42

Only three operations may be performed on a semaphore: initialize, increment, and __________ .

Question 43

In the case of _________ , messages are not sent directly from sender to receiver but rather are sent to a shared data structure consisting of queues that can temporarily hold messages.

Question 44

A monitor supports synchronization by the use of __________ that are contained within the monitor and accessible only within the monitor.

Question 45

The classic concurrency problem that involves multiple readers that can read from a shared data area when no single writer is exclusively writing to it is the _________ Problem.