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周测6

1.Consider the following three threads in a concurrent program that uses semaphores Sem1, Sem2, and Sem3.What are the initial values that can be given to the semaphores so that the threads cooperate to print a string that begins with 162162162162162?

Thread 1
L1: sema_down(Sem1);
  print("6");
  sema_up(Sem2);
goto L1;

Thread 2
L2: sema_down(Sem2);
  print("2");
  sema_up(Sem3);
goto L2;

Thread 3
L3: sema_down(Sem3);
  print("1");
  sema_up(Sem1);
goto L3;

编号	选项
A	sem1=0, sem2=0, sem3=0
B	sem1=1, sem2=1, sem3=1
C	sem1=0, sem2=1, sem3=0
D	sem1=0, sem2=0, sem3=1

2.Consider the following three threads in a concurrent program that uses semaphores Sem1, Sem2, and Sem3.What are the initial values that can be given to the semaphores so that the threads cooperate to print a string that begins with 621621621621621?

Thread 1
L1: sema_down(Sem1);
  print("6");
  sema_up(Sem2);
goto L1;

Thread 2
L2: sema_down(Sem2);
  print("2");
  sema_up(Sem3);
goto L2;

Thread 3
L3: sema_down(Sem3);
  print("1");
  sema_up(Sem1);
goto L3;

编号	选项
A	sem1=0, sem2=0, sem3=0
B	sem1=1, sem2=0, sem3=0
C	sem1=0, sem2=1, sem3=0
D	sem1=1, sem2=0, sem3=1

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最后更新: 2020-07-01