超星 - Chapter 5 Process synchronization

单选题

Two processes, P1 and P2, need to access a critical section of code. Consider the following synchronization construct used by the processes.Here, w1 and w2 have shared variables, which are initialized to false. Which one of the following statements is TRUE about the above construct?

A. It does not ensure mutual exclusion
B. It does not ensure bounded waiting
C. It requires that processes enter the critical section in strict alternation
D. It does not prevent deadlocks but ensures mutual exclusion

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单选题

What will happen if a non-recursive mutex is locked more than once?

A. Starvation
B. Deadlock
C. Aging
D. Signaling

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单选题

What is a semaphore?

A. is a binary mutex
B. must be accessed from only one process
C. can be accessed from multiple processes
D. none of the mentioned

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单选题

What is a mutex?

A. is a binary mutex
B. must be accessed from only one process
C. can be accessed from multiple processes
D. none of the mentioned

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单选题

At a particular time of computation the value of a counting semaphore is 7.Then 20 P operations and 15 V operations were completed on this semaphore. The resulting value of the semaphore is?

A. 42
B. 2
C. 7
D. 12

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单选题

A binary semaphore is a semaphore with integer values ____________

A. 1
B. -1
C. 0.8
D. 0.5

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单选题

The following pair of processes share a common variable X.X is set to 5 before either process begins execution. As usual, statements within a process are executed sequentially, but statements in process A may execute in any order with respect to statements in process B.How many different values of X are possible after both processes finish executing?

A. two
B. three
C. four
D. eight

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单选题

The program follows to use a shared binary semaphore T.T is set to 0 before either process begins execution and, as before, X is set to 5.Now, how many different values of X are possible after both processes finish executing?

A. one
B. two
C. three
D. four

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单选题

All processes share a semaphore variablemutex, initialized to 1. Each process must execute wait(mutex) before entering the critical section and signal(mutex) afterward.Suppose a process executes in the following manner.

A. a deadlock will occur
B. processes will starve to enter critical section
C. several processes maybe executing in their critical section
D. all of the mentioned

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单选题

Semaphores are mostly used to implement ____________

A. System calls
B. IPC mechanisms
C. System protection
D. None of the mentioned

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