Deck 20: Multithreading

Question 1

Given a single CPU and four threads, how many of the threads can execute in parallel?

A) Only 1 can execute at a time.
B) 2 can execute in parallel.
C) 3 can execute in parallel.
D) All 4 can execute in parallel.

Answer 1

A

Question 2

The Runnable interface includes which method(s)?
I public void run(Runnable runnable)
II public void run()
III public void start()

A) I
B) II
C) I and II
D) II and III

Answer 2

B

Question 3

When a sleeping thread is interrupted, a(n) ____________________ is generated.

A) ThreadInterruptedException
B) ThreadException
C) ThreadSleepException
D) InterruptedException

Answer 3

D

Question 4

Which of the following class declarations could run in a thread?
I public interface MyRunnable extends Runnable { . . . }
II public class MyRunnable extends Runnable { . . . }
III public class MyRunnable implements Runnable { . . . }

A) II
B) III
C) I and II
D) II and III

Question 5

To start a thread, you should first construct an object from a class that implements the ____________ interface.

A) Thread
B) Threadable
C) Run
D) Runnable

Question 6

The Runnable interface has a single method called ____________.

A) run
B) start
C) sleep
D) wait

Question 7

Which constructor can be used to create a new thread associated with a Runnable object?

A) public Thread(Runnable r)
B) public Thread()
C) public Runnable(Thread t)
D) public Thread(String s)

Question 8

If you do not use the Runnable interface, then what is necessary to create a new thread?
I Implement the Threadable interface
II Extend the Thread class and add a run() method to it
III Add a run method to any class

A) I
B) II
C) III
D) II and III

Question 9

For threads of equal priority, which is guaranteed by the thread scheduler that is part of the Java Virtual Machine?
I All will get time on the CPU
II All will get exactly equal time on the CPU
III The order threads run in the CPU will always be the same

A) I
B) II
C) I and III
D) II and III

Question 10

Which method(s) are part of the Thread class?
I public void run(Runnable runnable)
II public void start(Runnable runnable)
III public void start()

A) I
B) II
C) III
D) II and III

Question 11

Given a two-CPU machine and four threads, how many of the threads can execute in parallel?

A) Only 1 can execute at a time.
B) 2 can execute in parallel.
C) 3 can execute in parallel.
D) All 4 can execute in parallel.

Question 12

When a thread is interrupted, the most common response is to terminate the ____________ method.

A) run
B) thread
C) sleep
D) await

Question 13

Which of the following does not create an object that can run in a thread, assuming the following MyRunnable class declaration?
Public class MyRunnable implements Runnable { . . . }
I Runnable runnable = new Runnable();
II Runnable runnable = new MyRunnable();
III MyRunnable runnable = new MyRunnable();

A) I
B) III
C) I and II
D) II and III

Question 14

The _____________ interface is designed to encapsulate the concept of a sequence of statements that can run in parallel with other tasks, without equating it with the concept of a thread, a potentially expensive resource that is managed by the operating system.

A) Thread
B) Runnable
C) MyRunnable
D) Threadable

Question 15

The ________ method stops the current thread for a given number of milliseconds.

A) run
B) await
C) sleep
D) delay

Question 16

Which exception must be caught or declared when calling the sleep method?

A) IOException
B) IllegalStateMonitorException
C) InterruptedException
D) SleepException

Question 17

In which method are the tasks that are performed by a thread coded?

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

Question 18

When a sleeping thread is interrupted, an InterruptedException is generated. Where do you catch that exception?

A) in the start() method.
B) in the sleep() method.
C) in the run() method.
D) in the interrupt() method.

Question 19

Suppose run1 and run2 are objects of the class MyRunnable, which implements the Runnable interface. What is the result of the following calls?
Run1.run();
Run2.run();

A) run1 and run2 execute as independent threads.
B) Syntax error
C) Only run1 executes as an independent thread.
D) run1 and run2 run sequentially, not as independent threads.

Question 20

Which method do you call to make a thread ineligible to run on the CPU for a set number of milliseconds?

A) start
B) wait
C) await
D) sleep

Question 21

In the initial release of the Java library, the Thread class had a stop method to terminate a thread. However, that method is now _______________

A) forbidden
B) not recommended
C) unwise
D) deprecated

Question 22

Which argument(s) present(s) the best case(s) for extending the Thread class rather than using the Runnable interface in conjunction with a thread pool?
I Thread sub-classes will all execute independently
II Runnable objects will waste more system resources
III Thread sub-classes can execute faster on a single CPU than Runnable objects

A) I
B) II
C) III
D) II and III

Question 23

Insert the statement that would start the following thread.
Thread firstThread = new Thread(myRunnable);
____________________

A) firstThread.run();
B) firstThread.start();
C) run();
D) start();

Question 24

What course of action should be followed when a thread has been interrupted?

A) the thread should terminate
B) the thread should do what a programmer thinks is appropriate
C) the thread should go to sleep
D) the thread should call the Thread.interrupted method

Question 25

A(n) ____ uses a small number of threads to execute a large number of runnables.

A) embedded system
B) condition object
C) thread pool
D) race condition

Question 26

Suppose thread one is downloading a 800KB file while another thread is processing the same file on a single CPU machine. Suppose further that one time slice allows the first thread to download about 10KB and that the second thread can process 10KB of the file in one time slice. How many total time slices will it take to see the first 10KB of the processed file?

A) one
B) two
C) eight
D) ten

Question 27

Which of the following definitely indicates that a thread has been interrupted by another thread?
I The run method has completed
II The method Thread.interrupted returns true
III The run method catches an InterruptedException

A) I
B) II
C) I and II
D) II and III

Question 28

What should be done to get the attention of a thread?

A) call the thread's stop method
B) call the thread's run method
C) call the thread's interrupt method
D) call the thread's sleep method

Question 29

The sleep method is terminated with a(n) __________ whenever a sleeping thread is interrupted.

A) InterruptedException
B) SleepException
C) lock
D) SignalException

Question 30

Each thread runs for a short amount of time, called a ____________________.

A) thread allotment
B) thread time slot
C) time slice
D) run time slice

Question 31

What is likely to be true when thread one is downloading a 1MB file while thread two is downloading another 1MB file?

A) The files download twice as fast as they would if one thread downloaded both files.
B) The files download half as fast as they would if one thread downloaded both files.
C) When thread one is half done, thread two is about half done.
D) The faster thread will interrupt the other thread.

Question 32

The ___________ method does not actually cause threads to terminate; it merely sets a Boolean field in the thread data structure.

A) stop
B) await
C) sleep
D) interrupt

Question 33

Suppose thread one is downloading a 800KB file while another thread is processing the same file on a single CPU machine. Suppose further that one time slice allows the first thread to download about 10KB and that the second thread can process 10KB of the file in one time slice. How many total time slices will it take to process half the file?

A) thirty
B) forty
C) eighty
D) hundred

Question 34

Suppose thread one is downloading a 800KB file while another thread is processing the same file on a single CPU machine. Suppose further that one time slice allows the first thread to download about 10KB and that the second thread can process 10KB of the file in one time slice. Approximately how does the time to complete the entire job compare to having a single thread do the work?

A) The threaded way will be twice as fast.
B) The threaded way will be twice as slow.
C) The time depends heavily on the thread scheduler.
D) The ways will take about the same time.

Question 35

Suppose thread one is downloading a large file while another thread is processing the same file on a single CPU machine. Suppose further that one time slice allows the first thread to download about 10KB and that the second thread can process 10KB of the file in one time slice. What is the main benefit of using two threads rather than using a single thread to do both parts of the job?

A) accuracy of the results
B) speed to compete entire job
C) speed of availability of partial results
D) less memory is used

Question 36

Which argument(s) present(s) the best case(s) for using the Runnable interface rather than extending the Thread class?
I Thread sub-classes are harder to write
II Runnable objects can be passed into thread pools
III Less time is wasted in creating and destroying thread objects

A) I
B) II
C) II and III
D) I and II

Question 37

The ____________ occurs when a thread that is not running is interrupted.

A) InterruptException
B) InterruptedException
C) ThreadException
D) ThreadTerminatedException

Question 38

____ occur(s) if the effect of multiple threads on shared data depends on the order in which the threads are scheduled.

A) Pooling
B) Interrupted exceptions
C) Deadlocks
D) Race conditions

Question 39

Which of the following definitely indicates that a thread has terminated?
I The run method has completed
II The method Thread.interrupted returns true
III The run method catches an InterruptedException

A) I
B) II
C) I and II
D) II and III

Question 40

Suppose thread one is downloading a 800KB file while another thread is processing the same file on a multi-CPU machine. Suppose further that one time slice allows the first thread to download about 10KB and that the second thread can process 10KB of the file in one time slice. What is the minimum number of CPUs that will allow the job to be completed in roughly half the time of a single-CPU machine?

A) 1
B) 2
C) 3
D) 4

Question 41

Assume two threads share a BankAccount object with balance of zero (0), and that the BankAccount class provides deposit and withdraw methods as shown below. Thread one deposits $10 ten times and, concurrently, thread two withdraws $10 ten times. Suppose a race condition occurs, and the race is finished first by thread one. What would you expect balance to be after all thread calls?
Public void deposit(int dollars)
{
Int newBalance = balance + dollars;
System.out.println("depositing");
Balance = newBalance;
}
Public void withdraw(int dollars)
{
Int newBalance = balance - dollars;
System.out.println("withdrawing");
Balance = newBalance;
}

A) $10
B) $20
C) $0
D) a negative amount

Question 42

Assume two threads share a BankAccount object with balance of zero (0), and that the BankAccount class provides deposit and withdraw methods and has a ReentrantLock named myLock, as shown below. Note that only the deposit method uses the lock. Thread one deposits $10 ten times and, concurrently, thread two withdraws $10 ten times. Which statement regarding the balance after all thread calls is definitely true?
Public void deposit(int dollars)
{
MyLock.lock()
Int newBalance = balance + dollars;
System.out.println("depositing");
Balance = newBalance;
MyLock.unlock()
}
Public void withdraw(int dollars)
{
Int newBalance = balance - dollars;
System.out.println("withdrawing");
Balance = newBalance;
}

A) The balance could be zero or positive.
B) The balance is zero.
C) The balance could be zero or negative.
D) The balance is positive.

Question 43

Calling the wait method in synchronized code is very similar to what action after locking with a ReentrantLock object?

A) Calling notify.
B) Locking a ReentrantLock object.
C) Calling await on a condition object.
D) Calling signalAll on a condition object.

Question 44

The ________ method is called by a thread that has just changed the state of some shared data in a way that may benefit waiting threads.

A) run
B) lock
C) unlock
D) signalAll

Question 45

If a thread sleeps after acquiring a _________, it blocks all other threads that want to acquire it.

A) condition
B) signal
C) lock
D) thread

Question 46

Examine the SharedData class shown below. Suppose two threads are created so that each has access to the same SharedData object. Thread one calls setSharedData eight times with values 1...8 respectively, sleeping for 30 milliseconds between calls. Thread two calls getSharedData eight times, also sleeping for 30 milliseconds between calls. What is one reason why thread two may not receive 7 and 8 on its two final calls to getSharedData?
Public class SharedData
{
Private int value;
Public void setSharedData(int n)
{
Value = n;
}
Public int getSharedData()
{
Return value;
}
}

A) Thread one produced two 8's.
B) Thread two is getting longer time slices.
C) Thread one is getting longer time slices.
D) The race condition.

Question 47

Assume two threads share a BankAccount object with balance of zero (0), and that the BankAccount class provides deposit and withdraw methods as shown below. Thread one deposits $10 ten times and, concurrently, thread two withdraws $10 ten times. If the balance after all thread calls is 0, which statement is definitely true?
Public void deposit(int dollars)
{
Int newBalance = balance + dollars;
System.out.println("depositing");
Balance = newBalance;
}
Public void withdraw(int dollars)
{
Int newBalance = balance - dollars;
System.out.println("withdrawing");
Balance = newBalance;
}

A) The calls were interleaved: thread one, thread two, thread one, thread two, …
B) The first call was to the deposit method.
C) The last call was to the withdraw method.
D) Each individual call to the deposit and withdraw methods ran to completion.

Question 48

____ allow a thread to temporarily release a lock, so that another thread can proceed, and to regain the lock at a later time.

A) Condition objects
B) Embedded systems
C) Exceptions
D) Race conditions

Question 49

Consider the addFirst method of the LinkedList class in Chapter 16:
/**
Adds an element to the front of the linked list.
@param element the element to add
*/
Public void addFirst(Object element)
{
Node newNode = new Node();
NewNode.data = element;
NewNode.next = first;
First = newNode;
}
Three implementations have been proposed to make the addFirst method thread safe where listLock is a variable of type ReentrantLock. Which of them will work?
I)
ListLock.lock();
Try
{
Node newNode = new Node();
NewNode.data = element;
NewNode.next = first;
}
Finally
{
ListLock.unlock();
}
First = newNode;
II)
Node newNode = new Node();
NewNode.data = element;
NewNode.next = first;
ListLock.lock();
Try
{
First = newNode;
}
Finally
{
ListLock.unlock();
}
III)
ListLock.lock();
Try
{
Node newNode = new Node();
NewNode.data = element;
NewNode.next = first;
First = newNode;
}
Finally
{
ListLock.unlock();
}

A) None of them
B) III only
C) II and III only
D) All of them

Question 50

Consider the following change to the deposit method in Section 20.4:
Public void deposit(double amount)
{
BalanceChangeLock.lock();
Try
{
Double newBalance = balance + amount;
Balance = newBalance;
}
Finally
{
BalanceChangeLock.unlock();
}
System.out.println("Depositing " + amount + ", new balance is " + balance);
}
What is the consequence of this change?

A) The bank account balances may no longer be correctly updated.
B) The printouts may become intermingled.
C) The printouts may no longer display the correct balances.
D) All of the above.

Question 51

A waiting thread is blocked until another thread calls ____ on the condition object for which the thread is waiting.

A) await
B) signalAll
C) interrupt
D) lock

Question 52

Examine the SharedData class shown below. Suppose two threads are created so that each has access to the same SharedData object. Thread one calls setSharedData eight times with values 1...8 respectively, sleeping for 30 milliseconds between calls. Thread two calls getSharedData eight times, also sleeping for 30 milliseconds between calls. Which of the following orders of values is not possible for thread two to receive?
Public class SharedData
{
Private int value;
Public void setSharedData(int n)
{
Value = n;
}
Public int getSharedData()
{
Return value;
}
}

A) 1,2,3,4,5,6,7,8
B) 1,2,2,4,5,6,7,8
C) 1,2,3,4,5,6,8,8
D) 1,2,3,4,5,6,8,7

Question 53

Examine the SharedData class shown below. Suppose two threads are created so that each has access to the same SharedData object. Thread one calls setSharedData eight times with values 1...8 respectively, sleeping for 30 milliseconds between calls. Thread two calls getSharedData eight times, also sleeping for 30 milliseconds between calls. Suppose thread two receives values 1, 2, 3, 4, 5, 6, 7, 8 respectively on its calls. Should we expect the same values for each program run?
Public class SharedData
{
Private int value;
Public void setSharedData(int n)
{
Value = n;
}
Public int getSharedData()
{
Return value;
}
}

A) Yes, because the sleep times are equal in between calls.
B) Yes, because that's the same order used by thread one to set the values.
C) No, because thread one may not set the data as 1,2,3,4,5,6,7,8 respectively.
D) No, because a race condition may result in a different order.

Question 54

The thread that calls signalAll must own the lock that belongs to the condition object on which signalAll is called. Otherwise, a(n) _______ ________ is thrown.

A) InterruptException
B) IllegalMonitorStateException
C) ThreadException
D) ThreadTerminatedException

Question 55

A(n) ____ object is used to control the threads that want to manipulate a shared resource.

A) condition
B) lock
C) interrupt
D) runnable

Question 56

Examine the SharedData class shown below. Suppose two threads are created so that each has access to the same SharedData object. Thread one calls setSharedData ten times with values 1...10 respectively, sleeping for a random number of milliseconds between calls. Thread two calls getSharedData eight times, also sleeping for a random number of milliseconds between calls. Which of the following could be the last two values received by thread two?
Public class SharedData
{
Private int value;
Public void setSharedData(int n)
{
Value = n;
}
Public int getSharedData()
{
Return value;
}
}

A) 8, 10
B) 10, 9
C) 10, 8
D) 8, 7

Question 57

Which of the following statements is correct?

A) If a thread sleeps after acquiring a lock, it blocks all other threads that want to use the same lock.
B) When a thread calls await, it is simply deactivated in the same way as a thread that reaches the end of its time slice.
C) A thread pool is designed to encapsulate the concept of a sequence of statements that can run in parallel with other tasks, without equating it with the concept of a thread, a potentially expensive resource that is managed by the operating system.
D) Under no circumstances should you terminate a running thread.

Question 58

Examine the SharedData class shown below. Suppose two threads are created so that each has access to the same SharedData object. Thread one calls setSharedData eight times with values 1...8 respectively, sleeping for 100 milliseconds between calls. Thread two calls getSharedData eight times, also sleeping for 100 milliseconds between calls. Which of the following could be the last two values received by thread two?
Public class SharedData
{
Private int value;
Public void setSharedData(int n)
{
Value = n;
}
Public int getSharedData()
{
Return value;
}
}

A) 9, 10
B) 10, 9
C) 1, 2
D) 8, 7

Question 59

The ____ method is useful only if you know that a waiting thread can actually proceed.

A) run
B) signal
C) await
D) interrupted

Question 60

Assume two threads share a BankAccount object with balance of zero (0), and that the BankAccount class provides deposit and withdraw methods and has a ReentrantLock named myLock, as shown below. Thread one deposits $10 ten times and, concurrently, thread two withdraws $10 ten times. Which statement regarding the balance after all thread calls is definitely true?
Public void deposit(int dollars)
{
MyLock.lock()
Int newBalance = balance + dollars;
System.out.println("depositing");
Balance = newBalance;
MyLock.unlock()
}
Public void withdraw(int dollars)
{
MyLock.lock()
Int newBalance = balance - dollars;
System.out.println("withdrawing");
Balance = newBalance;
MyLock.unlock()
}

A) The balance could be zero or positive.
B) The balance is zero.
C) The balance could be zero or negative.
D) The balance is positive.

Question 61

Under what circumstances will a call to signalAll not release a blocked thread that has called await?

A) When the thread is sleeping.
B) When the thread called await on different condition object.
C) When two or more threads are waiting.
D) When the thread called await on the same condition object.

Question 62

Stale data occurs in multi-CPU machines when one thread modifies shared data and a second thread accesses that data later, but sees the data value before the change took place. What is required to guarantee that the second thread sees the updated data, not stale data?

A) The second thread should not try to acquire the lock.
B) The first thread should not try to acquire the lock.
C) Neither thread should use locks.
D) The first thread should release the lock after changing the data.

Question 63

Assume two threads share a BankAccount object with balance of zero (0), and that the BankAccount class provides synchronized deposit and withdraw methods. Thread one deposits $10 ten times and, concurrently, thread two withdraws $10 ten times. Which statement regarding the balance after all thread calls is definitely true?
Public synchronized void deposit(int dollars)
{
Int newBalance = balance + dollars;
System.out.println("depositing");
Balance = newBalance;
}
Public synchronized void withdraw(int dollars)
{
Int newBalance = balance - dollars;
System.out.println("withdrawing");
Balance = newBalance;
}

A) The balance could be zero or positive.
B) The balance is zero.
C) The balance could be zero or negative.
D) The balance is positive.

Question 64

Which of the following scenarios may not always cause a deadlock among two threads?
I Thread one is in an infinite loop and has acquired a lock
II Both threads are in an infinite loop, and one thread has acquired a lock
III Both threads are in an infinite loop, and both threads have acquired locks

A) I
B) II
C) III
D) I, II or III

Question 65

Stale data occurs in multi-CPU machines when one thread modifies shared data and a second thread accesses that data later, but sees the data value before the change took place. What is required to guarantee that the second thread sees the updated data, not stale data when access to the shared data occurs in two different methods?

A) One method needs to acquire then release the lock after modifying the data.
B) Both methods need to acquire then release the lock after modifying or reading the data.
C) Never change any shared object data in multi-CPU machines.
D) Never use locks for any shared data in multi-CPU machines.

Question 66

Under what conditions are locks unnecessary for multi-threaded programs?

A) When the threads are all of the same class.
B) When the threads are different classes.
C) When the threads do not share data.
D) When the shared data only has a single method.

Question 67

When is it a good idea to call notifyAll in a synchronized method?

A) Whenever you exit it.
B) Upon exit, but only if threads before have called wait.
C) Upon exit, but only if the thread has replenished a needed resource.
D) Immediately upon entering the method.

Question 68

Consider an old fashioned telephone booth that can be occupied by one person at a time. Suppose one person went in and dialed a part of her number, and had to leave the booth. A second person went in and dialed a part of his number, and before the number was fully dialed, a connection to some other phone was made. What Java threads analogy fits this scenario?
I The two people are the threads
II The shared data is the telephone
III The state of the object is corrupt

A) I
B) I and II
C) II and III
D) I, II and III

Question 69

What happens when a thread calls the signalAll method of a Condition object connected to a lock, if no other thread had called await on that Condition object?

A) A compiler error.
B) A checked exception is thrown.
C) The unlock method call will block.
D) Nothing, the program executes normally.

Question 70

Assume three threads share a BankAccount object with balance of zero (0), a ReentrantLock named myLock, and has a condition object on myLock named lowBalanceCondition, as shown below. Thread one calls withdraw(30), then thread two calls withdraw(20)and thread three calls deposit(45). If the starting balance is 0, what is the balance after the three calls and after the waiting threads have had a chance to run?
Public void deposit(int dollars)
{
MyLock.lock();
Int newBalance = balance + dollars;
System.out.println("depositing");
Balance = newBalance;
LowBalanceCondition.signalAll();
MyLock.unlock();
}
Public void withdraw(int dollars)
{
MyLock.lock();
While (balance < dollars)
{
LowBalanceCondition.await();
}
Int newBalance = balance - dollars;
System.out.println("withdrawing");
Balance = newBalance;
MyLock.unlock();
}

A) 0
B) 15 or 25
C) 45
D) -5

Question 71

Assume three threads share a BankAccount object with balance of zero (0), a ReentrantLock named myLock, and a condition object on myLock named lowBalanceCondition, as shown below. Thread one calls withdraw(30), then thread two calls withdraw(20)and thread three calls deposit(45). If the starting balance is 0, what is the balance after the three calls?
Public void deposit(int dollars)
{
MyLock.lock();
Int newBalance = balance + dollars;
System.out.println("depositing");
Balance = newBalance;
MyLock.unlock();
}
Public void withdraw(int dollars)
{
MyLock.lock();
While (balance < dollars)
{
LowBalanceCondition.await();
}
Int newBalance = balance - dollars;
System.out.println("withdrawing");
Balance = newBalance;
MyLock.unlock();
}

A) 0
B) 15 or 25
C) 45
D) -5

Question 72

What happens if we try to start a thread with an instance of a Runnable class that did not override the run method?

A) A compiler error.
B) A checked exception is thrown.
C) The inherited method runs and does nothing.
D) The thread sleeps indefinitely.

Question 73

Consider an old fashioned telephone booth that can be occupied by one person at a time. Suppose one person went in and dialed a part of her number, and had to leave the booth. A second person went in and dialed a part of his number, and before the number was fully dialed, a connection to some other phone was made. What Java threads analogy would prevent this undesirable scenario?
I Acquire the lock prior to entering the booth
II Dial a complete number when inside the booth
III Hang up the phone and release the lock upon exiting the booth

A) I
B) I and II
C) I and III
D) I, II and III

Question 74

A GUI should be responsive to the user. If a GUI interaction starts a time-consuming task, the GUI may not be responsive to the user until the task completes. Which approach would make the GUI responsive under these circumstances?

A) As you run the task, break and check for events.
B) Ask the user if she is sure she wants to run the task.
C) Run the task in a separate thread.
D) Disable the GUI during the task.

Question 75

Exactly when does a thread finish in Java?

A) When its main method ends.
B) When its run method ends.
C) When it calls the method await.
D) When it is interrupted.

Question 76

What is the relationship between synchronized code and code that is locked using a ReentrantLock object?

A) synchronized code stops the race condition, locks do not.
B) synchronized is a single lock, but we may have many ReentrantLock objects.
C) The two are exactly the same.
D) The two concepts are not related.

Question 77

Which phrase best describes the purpose of a lock used in an object in one or more of its methods?

A) increased sharing
B) mutual exclusion
C) speed increase
D) privacy protection

Question 78

"Livelock" occurs when one thread runs continuously, while another thread never does. Which of the following is sufficient to cause livelock?
I Thread one is in an infinite loop
II Thread one possesses a lock and does not unlock it, but thread two requires the lock
III Thread one requires a lock, but thread two possesses the lock

A) I
B) II
C) I and II
D) I and III

Question 79

Class MyClass has a single ReentrantLock object, myLock. Suppose thread one calls myLock.lock() as it enters methodX and immediately completes its CPU time slice. What will happen as thread two calls methodY and attempts to call myLock.lock()?

A) Thread two will wait for the lock.
B) Thread two will acquire the lock.
C) Deadlock will occur.
D) Thread two causes the IllegalStateMonitorException.

Question 80

Class MyClass has two ReentrantLock objects, myLock1 and myLock2. Suppose thread one acquires myLock1 as it enters methodX and immediately completes its CPU time slice. After thread two enters methodY, it acquires myLock2 and tries to acquire myLock1. When thread one resumes, it tries to acquire myLock2. What will happen next?

A) Thread two will acquire myLock1.
B) Thread one will acquire myLock2.
C) Deadlock will occur.
D) Thread two will release myLock2.