Operating Systems - Producer-Consumer Problem Using Semaphores
In a producer-consumer system using semaphores, what problem arises if the producer signals the 'full' semaphore before acquiring the mutex to add an item to the buffer?
In a producer-consumer system using semaphores, what problem arises if the producer signals the 'full' semaphore before acquiring the mutex to add an item to the buffer?
easy📖 Theory Q3 of Q15
Step-by-Step Solution
Solution:
Step 1: Understand semaphore roles
'Full' semaphore signals availability of items; mutex protects buffer access.Step 2: Incorrect signaling order
If 'full' is signaled before mutex acquisition, consumer may wake and read buffer before item is fully inserted.Step 3: Resulting issue
This causes consumers to read invalid or uninitialized data, leading to race conditions.Final Answer:
Option C -> Option CQuick Check:
Signal after mutex release to ensure data consistency [OK]
Quick Trick: Signal 'full' only after mutex release to avoid race [OK]
Common Mistakes:
MISTAKES- Assuming signaling order doesn't affect data integrity.
- Believing deadlock occurs instead of race condition.
- Confusing buffer size changes with synchronization errors.
Trap Explanation:
PITFALL- Incorrect order causes race conditions, not deadlocks or buffer resizing.
Interviewer Note:
CONTEXT- Tests understanding of correct semaphore signaling order and its impact on data consistency.
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