A semaphore is a shared integer variable __________
2024
A semaphore is a shared integer variable __________
Answer: A. that can not drop below zero — ConceptA semaphore represents a non-negative count used for synchronization. A wait operation decrements a positive count atomically; when the count is zero,…
- A.
that can not drop below zero
- B.
that can not be more than zero
- C.
that can not drop below one
- D.
that can not be more than one
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Show answer & explanation
Correct answer: A
Concept
A semaphore represents a non-negative count used for synchronization. A wait operation decrements a positive count atomically; when the count is zero, the caller blocks instead of making the count negative.
Application
The permitted values therefore begin at 0 and may rise above 1 for a counting semaphore. The shared integer cannot drop below zero.
Cross-check
A count of 0 represents no currently available permit, so 1 cannot be the lower bound.
A counting semaphore may represent several permits, so neither 0 nor 1 is a general upper bound.
Result: the semaphore cannot drop below zero.