In a system where multiple producers and consumers share a fixed-size buffer, which synchronization mechanism best ensures that producers wait when the buffer is full and consumers wait when the buffer is empty?

easy🔍 Pattern Recognition Q11 of Q15

Operating Systems - Producer-Consumer Problem Using Semaphores

AMutex lock only to protect buffer access

BSpinlocks to busy-wait until buffer space is available

CCounting semaphores to track empty and full slots along with a mutex for mutual exclusion

DCondition variables without any semaphore or mutex

Step-by-Step Solution

Step 1: Identify synchronization needs
Producers must wait if the buffer is full; consumers must wait if empty. This requires tracking counts of empty and full slots.
Step 2: Role of counting semaphores
Counting semaphores elegantly track available slots (empty) and filled slots (full), enabling blocking waits without busy-waiting.
Step 3: Need for mutual exclusion
A mutex is required to protect concurrent access to the buffer itself to avoid race conditions.
Step 4: Why other options fail
Mutex alone (A) cannot block producers/consumers based on buffer state; spinlocks (C) waste CPU cycles; condition variables (D) require mutexes and signaling to work correctly in this scenario.
Final Answer:
Option C -> Option C
Quick Check:
Counting semaphores + mutex is the classic producer-consumer solution [OK]

Quick Trick: Counting semaphores track buffer state; mutex protects access

Common Mistakes:

MISTAKES

Assuming mutex alone handles waiting
Using spinlocks wastes CPU
Thinking condition variables alone suffice

Trap Explanation:

PITFALL

Mutex alone protects critical section but doesn't block on buffer full/empty; spinlocks look simple but cause busy-waiting; condition variables need mutex and signaling, so alone they are insufficient.

Interviewer Note:

CONTEXT

Tests candidate's ability to identify correct synchronization primitives for producer-consumer problem

Master "Producer-Consumer Problem Using Semaphores" in Operating Systems

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More Operating Systems Quizzes

In a system where multiple producers and consumers share a fixed-size buffer, which synchronization mechanism best ensures that producers wait when the buffer is full and consumers wait when the buffer is empty?

Step 1: Identify synchronization needs

Step 2: Role of counting semaphores

Step 3: Need for mutual exclusion

Step 4: Why other options fail

Final Answer:

Quick Check:

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