假设某计算机系统中资源R的可用数为6，系统中有3个进程竞争R，且每个进程都需要i个R，该系统可能会发生死锁的最小i值是（）。若信号量S的当前值为-2，则R的可用数和等待R的进程数分别为（请作答此空）。
- A.0、0
- B.0、1
- C.1、0
- D.0、2
正确答案及解析
正确答案
解析
如果i=1，即每个进程都需要1个R，3个进程同时运行需要3个R，还剩3个R，不会发生死锁。如果i=2，即每个进程都需要2个R，3个进程同时运行需要6个R，而R的可用数正好为6，不会发生死锁。如果i=3，即每个进程都需要2个R，当3个进程分别占有2个R时，都需要再申请一个R资源才能正常运行，但此时已经没有R资源了，进程之间便出现了相互等待的状况，发生死锁。信号量的值小于0，表示没有可用的资源，其绝对值表示阻塞队列中等待该资源的进程数。
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