The producer and consumer processes share the following variables: int n…
2018
The producer and consumer processes share the following variables: int n Semaphore M = 1 Semaphore E = n Semaphore F = 0
The consumer process must execute ____ and ____ before removing an item from buffer.
- A.
signal(M), signal(F)
- B.
signal(M), wait(F)
- C.
signal(F), wait(M)
- D.
wait(F), wait(M)
Attempted by 451 students.
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Correct answer: D
Summary of correction: The option that states "signal(M), signal(F)" is incorrect. The correct operations the consumer must perform before removing an item are "wait(F), wait(M)".
M (mutex): ensures mutual exclusion when accessing the buffer.
E (empty): counts the number of empty slots available in the buffer.
F (full): counts the number of filled slots (items) in the buffer.
Required steps before removing an item:
wait(F): Decrement the full semaphore to ensure there is at least one filled slot (i.e., ensure an item exists to consume).
wait(M): Acquire the mutex to enter the critical section and safely remove the item from the buffer.
Actions after removing the item:
signal(M): Release the mutex so other processes can access the buffer.
signal(E): Increment the empty semaphore to indicate an additional empty slot is available.
Conclusion: The correct sequence the consumer must execute before removing an item is wait(F) followed by wait(M). The provided answer that lists signal(M) and signal(F) is incorrect and should be updated to the sequence wait(F), wait(M).