Deck 5: Process Management

Question 1

Resource holding, where a job holds on to one resource while waiting for another one that's not yet available, could be sidestepped by forcing each job to request, at creation time, every resource it will need to run to completion.

Answer 1

True

Question 2

It is easy to design a foolproof deadlock prevention policy.

Answer 2

False

Question 3

Locking can be done only at the level of the entire database.

Answer 3

False

Question 4

Deadlock was a serious problem for early batch systems.

Question 5

Most systems have transformed the printer into a sharable device by installing a high-speed device, a disk, between it and the CPU.

Question 6

Mutual exclusion should be eliminated from a computer system to avoid deadlock.

Question 7

Deadlocks are most serious in real-time systems.

Question 8

In many cases, there exists at least one allocation of resources sequence that will allow jobs to continue without becoming deadlocked.

Question 9

When modeling deadlock, if there's a cycle in the graph, then there is a deadlock involving the processes and the resources in the cycle.

Question 10

According to the Banker's Algorithm an unsafe state always leads to deadlock.

Question 11

Deadlock is a system-wide tangle of resource requests that begins when two or more jobs are put on hold, each waiting for a vital resource to become available.

Question 12

A race introduces the element of chance, an element that is desirable in database management.

Question 13

In a directed graph used to model deadlock, processes are represented using squares.

Question 14

A deadlock is preceded by five simultaneous conditions that are not necessary for the operating system to run smoothly.

Question 15

If locks are not used to preserve their integrity, the updated records in a database might include only some of the data-and their contents would depend on the order in which each process finishes its execution.

Question 16

The operating system must be sure never to satisfy a request that moves it from a safe state to an unsafe one.

Question 17

Although the Banker's Algorithm has been used to avoid deadlocks in systems with a few resources, it isn't always practical for most systems.

Question 18

Deadlock does not usually affect the entire system.

Question 19

A livelock is caused by two processes accessing different areas of the same disk.

Question 20

One problem with the Banker's Algorithm is that resources aren't well utilized because the algorithm assumes the worst case and, as a result, keeps vital resources unavailable to guard against unsafe states.

Question 21

Interactive systems generally improve the use of resources through ____ resource sharing, but this resource sharing capability also increases the possibility of deadlocks.

A) interspersed
B) group
C) dynamic
D) static

Question 22

Deadlock occurs on a modern printer when ____.

A) The network connection for the printer overflows with too many requests to use the printer.
B) Too many users attempt to access the printer at the same time.
C) The buffer fills up with too many print jobs and the printer cannot decide which one to print.
D) The printer needs all of a job's output before it will begin printing, but the spooling system fills the available disk space with only partially completed output.

Question 23

____ is when each process involved in the impasse is waiting for another to voluntarily release the resource so that at least one will be able to continue on.

A) Mutual exclusion
B) Resource holding
C) Circular wait
D) No preemption

Question 24

For ____ systems, deadlocks quickly become critical situations.

A) batch
B) interactive
C) real-time
D) general purpose

Question 25

A network that's congested or has filled a large percentage of its I/O buffer space can become deadlocked if it doesn't have ____ to control the flow of messages through the network.

A) procedures
B) protocols
C) policies
D) rules

Question 26

Starvation is the result of the liberal allocation of resources.

Question 27

Fill in the missing event that causes deadlock in a database. There are two processes (P1 and P2), each of which needs to update two records (R1 and R2) and the following sequence leads to a deadlock: 1. P1 accesses R1 and locks it.
2) P2 accesses R2 and locks it.
3) ____
4) P2 requests R1, which is locked by P1.

A) P2 releases R2.
B) P1 requests R1 again.
C) P1 requests R2, which is locked by P2.
D) P2 releases R1.

Question 28

____ is when, in modern printing systems, a disk accepts output from several users and acts as a temporary storage area for all output until the printer is ready to accept it.

A) Buffering
B) Lagging
C) Spooling
D) Spoofing

Question 29

In the dining philosophers problem there are five philosophers and four forks.

Question 30

Failure to lock database records before updating them may result in a ____ between processes.

A) struggle
B) race
C) deadlock
D) livelock

Question 31

Consider the case of a home construction company with two application programs, purchasing (P1) and sales (P2), which are active at the same time. They each need to access two files, inventory (F1) and suppliers (F2), to update daily transactions. The following series of events will cause a deadlock. Fill in the missing event in the sequence.
1) Purchasing (P1) accesses the supplier file (F2).
2) Sales (P2) accesses the inventory file (F1).
3) Purchasing (P1) doesn't release the supplier file (F2) but requests the inventory file (F1), but P1 is blocked because F1 is being held by P2.
4) Meanwhile, ____

A) sales (P2) doesn't release the inventory file (F1) but requests the supplier file (F2)
B) sales (P2) does release the inventory file (F1) and then requests the supplier file (F2)
C) purchasing (P1) does release the supplier file (F2) which is then requested by sales (P2)
D) purchasing (P1) exits

Question 32

Fill in the missing event that causes livelock. At an insurance company the system performs many daily transactions. One day the following series of events ties up the system:
1) Process P1 wishes to show a payment so it issues a command to read the balance, which is stored in cylinder 20 of a disk pack.
2) ____
3) P2 gains control of the I/O channel and issues a command to write someone else's payment to a record stored in cylinder 310. If the command is not "locked out," P2 will be put on hold while the control unit moves the arm to cylinder 310.
4) Because P2 is "on hold," the channel is free to be captured again by P1, which reconfirms its command to "read from cylinder 20."
5) Since the last command from P2 had forced the arm mechanism to cylinder 310, the disk control unit begins to reposition the arm to cylinder 20 to satisfy P1. The I/O channel would be released because P1 is once again put on hold, so it could be captured by P2, which issues a WRITE command only to discover that the arm mechanism needs to be repositioned.

A) While the control unit is moving the arm to cylinder 20, P1 is put on hold and the I/O channel is free to process the next I/O request.
B) P1 discovers that another process has locked the portion of the disk it needs to access.
C) P2 is put on hold while the control unit moves the arm to satisfy P1's request
D) P1 is unable to find the information it needs, so requests a different READ operation for a different cylinder.

Question 33

____ is the act of allowing only one process to have access to a dedicated resource.

A) No preemption
B) Circular wait
C) Resource holding
D) Mutual exclusion

Question 34

Fill in the missing step in the following deadlock situation. Two users from the local board of education are each running a program (P1 and P2), and both programs will eventually need two tape drives to copy files from one tape to another. Only two tape drives are available and they're allocated on an "as requested" basis. Soon the following sequence transpires: 1. P1 requests tape drive 1 and gets it.
2) ____
3) P1 requests tape drive 2 but is blocked.
4) P2 requests tape drive 1 but is blocked.

A) P1 requests tape drive 2.
B) P2 requests tape drive 2 and gets it.
C) P2 requests tape drive 1 but is blocked.
D) P1 releases tape drive 1.

Question 35

____ showed how the four conditions can be modeled using directed graphs.

A) Havender
B) Holt
C) Dijkstra
D) Lane & Mooney

Question 36

____ allows a resource to be held by a process as long as it is needed.

A) No preemption
B) Circular wait
C) Resource holding
D) Mutual exclusion

Question 37

When recovering from deadlock, jobs close to completion are usually left alone.

Question 38

Once starvation has been detected, an algorithm can be implemented in which the system blocks new jobs until the starving jobs have been satisfied.

Question 39

____ occurs when two processes do not release control of resources they are using.

A) No preemption
B) Circular wait
C) Resource holding
D) Mutual exclusion

Question 40

There are several recovery algorithms, but they all have one feature in common: they all require at least one victim, an expendable job, which, when removed from the deadlock, will free the system.

Question 41

The first step in reducing a directed graph to eliminate deadlock is ____.

A) Remove the process that is holding on to the most resources.
B) Find a process that's waiting only for resource classes that aren't fully allocated
C) Find a process that is currently using a resource and not waiting for one.
D) Find the oldest process and remove it from the graph.

Question 42

Assume the following events and actions take place. The following statement,____ is true.Event Action 1 P1 requests and is allocated R1.
2 P2 requests and is allocated R2.
3 P3 requests and is allocated R3.
4 P1 requests R2.
5 P2 requests R3.
6 P3 requests R1.

A) There is no deadlock.
B) Event 4 caused deadlock.
C) Event 5 caused deadlock.
D) Event 6 caused deadlock.

Question 43

In the "dining philosophers" problem, a philosopher can pick up a fork when____.

A) When there is one available
B) When there are two available
C) When no other philosopher is eating
D) When it is his turn, going in numerical order from one philosopher to the next

Question 44

____ developed the Banker's Algorithm.

A) Havender
B) Holt
C) Dijkstra
D) Lane & Mooney

Question 45

In a directed graph used to model deadlock, ____ represents deadlock.

A) a solid arrow
B) a dashed arrow
C) a cycle
D) any path

Question 46

____ is necessary in any computer system because some resources such as memory, CPU, and dedicated devices must be exclusively allocated to one user at a time.

A) Mutual exclusion
B) Resource holding
C) No preemption
D) Circular wait

Question 47

The first and simplest recovery method, and the most drastic, is to ____.

A) select a nondeadlocked job, preempt the resources it's holding, and allocate them to a deadlocked process so it can resume execution, thus breaking the deadlock
B) identify which jobs are involved in the deadlock and terminate them one at a time, checking to see if the deadlock is eliminated after each removal
C) terminate only the jobs involved in the deadlock and ask their users to resubmit them
D) terminate every job that's active in the system and restart them from the beginning

Question 48

Assume the following events and actions take place. The following statement, ____ is true.Event Action 1 P1 requests and is allocated the printer R1.
2 P1 releases the printer R1.
3 P2 requests and is allocated the disk drive R2.
4 P2 releases the disk R2.
5 P3 requests and is allocated the plotter R3.
6 P3 releases the plotter R3.

A) There is no deadlock.
B) Event 4 caused deadlock.
C) Event 5 caused deadlock.
D) Event 6 caused deadlock.

Question 49

The scheme of ____ removes the possibility of a circular wait and therefore guarantees the removal of deadlocks.

A) hierarchical ordering
B) preemption
C) saving and restoring job state
D) requesting all resources before job run

Question 50

An algorithm designed to detect starvation by tracking how long each job has been waiting for resources is the same concept as ____.

A) deadlock
B) aging
C) preemption
D) round robin