Deck 6: Concurrency: Deadlock and Starvation

Question 1

An indirect method of deadlock prevention is to prevent the occurrence of a circular wait.

Answer 1

False

Question 2

All deadlocks involve conflicting needs for resources by two or more processes.

Answer 2

True

Question 3

With _________ only one process may use a resource at a time and no process may access a resource unit that has been allocated to another process.

A) hold and wait
B) mutual exclusion
C) no preemption
D) circular wait

Answer 3

B

Question 4

A signal is similar to a hardware interrupt but does not employ priorities.

Question 5

A closed chain of processes exists, such that each process holds at least one resource needed by the next process in the chain is the condition of __________ .

A) no preemption
B) mutual exclusion
C) circular wait
D) hold and wait

Question 6

Deadlock is permanent because none of the events is ever triggered.

Question 7

An unsafe state is one in which there is at least one sequence of resource allocations to processes that does not result in a deadlock.

Question 8

Once the processes have progressed into the __________ , those processes will deadlock.

A) fatal region
B) regional resources
C) spinlock
D) hold and wait

Question 9

Deadlock avoidance is more restrictive than deadlock prevention.

Question 10

A set of processes is _________ when each process in the set is blocked awaiting an event that can only be triggered by another blocked process in the set.

A) spinlocked
B) stagnant
C) preempted
D) deadlocked

Question 11

An atomic operation executes without interruption and without interference.

Question 12

Deadlock avoidance requires knowledge of future process resource requests.

Question 13

Examples of __________ include processors, I/O channels, main and secondary memory, devices, and data structures such as files, databases, and semaphores.

A) regional resources
B) joint resources
C) reusable resources
D) consumable resources

Question 14

A useful tool in characterizing the allocation of resources to processes is the resource allocation graph.

Question 15

If access to a resource requires mutual exclusion then mutual exclusion must be supported by the OS

Question 16

The dining philosophers' problem can be representative of problems dealing with the coordination of shared resources which may occur when an application includes concurrent threads of execution.

Question 17

Interrupts, signals, messages, and information in I/O buffers are all examples of reusable resources.

Question 18

For deadlock to occur, there must not only be a fatal region, but also a sequence of resource requests that has led into the fatal region.

Question 19

The OS may preempt the second process and require it to release its resources if a process requests a resource that is currently held by another process.

Question 20

A mutex is used to ensure that only one thread at a time can access the resource protected by the mutex.

Question 21

The strategy of resource allocation denial is referred to as the ___________ .

Question 22

The __________ condition can be prevented by defining a linear ordering of resource types.

A) hold and wait
B) no preemption
C) mutual exclusion
D) circular wait

Question 23

The _________ condition can be prevented by requiring that a process request all of its required resources at one time and blocking the process until all requests can be granted simultaneously.

A) mutual exclusion
B) hold and wait
C) circular wait
D) no preemption

Question 24

_________ strategies are very conservative and solve the problem of deadlock by limiting access to resources and by imposing restrictions on processes.

Question 25

The most common technique used for protecting a critical section in Linux is the __________ .

A) signal
B) atomic bitmap operation
C) atomic integer operation
D) spinlock

Question 26

A __________ is a software mechanism that informs a process of the occurrence of asynchronous events.

A) signal
B) message
C) mailbox
D) kernel

Question 27

The fastest form of interprocess communication provided in UNIX is __________ .

A) shared memory
B) message
C) pipe
D) semaphore

Question 28

The _________ is useful in sending a signal to a thread indicating that a particular event has occurred.

A) mutex object
B) semaphore object
C) event object
D) waitable timer object

Question 29

Three conditions of policy must be present for a deadlock to be possible: mutual exclusion, no preemption, and _________ .

Question 30

One of the most significant contributions of UNIX to the development of operating systems is the _________ .

A) semaphore
B) shared memory
C) message
D) pipe

Question 31

Three general approaches exist for dealing with deadlock: prevent, avoid, and __________ .

Question 32

The _________ of the system reflects the current allocation of resources to processes.

Question 33

_________ can be defined as the permanent blocking of a set of processes that either compete for system resources or communicate with each other.

Question 34

The strategy of deadlock _________ is to design a system in such a way that the possibility of deadlock is excluded.

A) prevention
B) detection
C) diversion
D) avoidance

Question 35

A _________ resource is one that can be created and destroyed.

Question 36

The _________ allows multiple threads to have simultaneous read-only access to an object protected by the lock.

A) barrier
B) condition variable
C) readers/writer lock
D) mutex

Question 37

A _________ resource is one that can be safely used by only one process at a time and is not depleted by that use.

Question 38

Requested resources are granted to processes whenever possible with _________ .

A) preemption
B) deadlock detection
C) mutual exclusion
D) deadlock avoidance

Question 39

__________ allows the three necessary conditions but makes judicious choices to assure that the deadlock point is never reached.

Question 40

The _________ is a directed graph that depicts a state of the system of resources and processes, with each process and each resource represented by a node.

Question 41

Inspired by the concept of co-routines, a _________ is a circular buffer allowing two processes to communicate on the producer-consumer model.

Question 42

A program invocation, including the address space and resources required to run the program is a __________ object.

Question 43

Two types of atomic operations are defined in Linux: integer operations and __________ .

Question 44

Linux provides three types of semaphore facilities in the kernel: binary semaphores, counting semaphores, and __________ .

Question 45

An executable entity within a process is a __________ object.