Two processes X and Y need to access a critical section. Consider the following synchronization construct used by both the processes Here, varP and varQ are shared variables and both are initialized to false. Which one of the following statements is true? A) The proposed solution prevents deadlock but fails to guarantee mutual exclusion B) The proposed solution guarantees mutual exclusion but fails to prevent deadlock C) The proposed solution guarantees mutual exclusion and prevents deadlock D) The proposed solution fails to prevent deadlock and fails to guarantee mutual exclusion

Official answer: A) The proposed solution prevents deadlock but fails to guarantee mutual exclusion. Explanation: Let us analyze the synchronization code: 1. Mutual Exclusion: - Initially, `varP = false` and `varQ = false`. - Suppose Process X sets `varP = true`. Before evaluating its `while` condition, a context switch occurs to Process Y. - Process Y sets `varQ = true`. - Now, Process X checks `while(varQ == true)`, which evaluates to `true`, so X enters the `while` loop body and thus the Critical Section. - Simultaneously, Process Y checks `while(varP == true)`, which also evaluates to `true`, so Y enters the `while` loop body and thus the Critical Section at the same time. - Therefore, mutual exclusion is not guaranteed. 2. Deadlock: - Neither process can be blocked in an infinite busy-wait loop because there are no loops without exit conditions or blocking waits; the loop is entered only if the condition is true and immediately resets the flag inside, or skipped if false. - Hence, deadlock is prevented. Thus, the proposed solution prevents deadlock but fails to guarantee mutual exclusion, which matches (A).

A) The proposed solution prevents deadlock but fails to guarantee mutual exclusion

B) The proposed solution guarantees mutual exclusion but fails to prevent deadlock

C) The proposed solution guarantees mutual exclusion and prevents deadlock

D) The proposed solution fails to prevent deadlock and fails to guarantee mutual exclusion

Operating Systems · Concurrency and Synchronization

Official IIT answer key · IIT Kanpur · Audited Aug 2026

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GATE CSE 2015 Set 3 Q10 · MCQ · 1 mark

Two processes $X$ and $Y$ need to access a critical section. Consider the following synchronization construct used by both the processes Here, `varP` and `varQ` are shared variables and both are initialized to false. Which one of the following statements is true?

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Concurrency and Synchronization

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How GATE tests Concurrency and Synchronization

Concurrency and Synchronization is consistently evaluated through rigorous interleaving analysis, semaphore tracing, and correctness verification of mutual exclusion algorithms. Over the years, GATE tests whether candidates can systematically trace race conditions, identify potential deadlocks from mismatched semaphore wait/signal orders, and compute the bounds or exact sets of possible shared variable values under non-atomic operations. Recent papers heavily favor Multi-Select Questions (MSQs) requiring complete enumeration of all valid execution traces and program outcomes.

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Independent practice explanation verified by the GateAI team. GATE is conducted by the IITs; question text follows the official paper.

Operating Systems · Concurrency and Synchronization

Official IIT answer key · IIT Kanpur · Audited Aug 2026

Take topic test

GATE CSE 2015 Set 3 Q10 · MCQ · 1 mark

Two processes $X$ and $Y$ need to access a critical section. Consider the following synchronization construct used by both the processes Here, `varP` and `varQ` are shared variables and both are initialized to false. Which one of the following statements is true?

Select an option to check

Key concept

Concurrency and Synchronization

Step-by-step verified solution

Examiner trap & misconception

Topic notes

How GATE tests Concurrency and Synchronization

Full Concurrency and Synchronization guide →

More on Concurrency and Synchronization

All 18 questions on Concurrency and Synchronization →

Independent practice explanation verified by the GateAI team. GATE is conducted by the IITs; question text follows the official paper.

Two processes $X$ and $Y$ need to access a critical section. Consider the following synchronization construct used by both the processes Here, `varP` and `varQ` are shared variables and both are initialized to false. Which one of the following statements is true?

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Two processes $X$ and $Y$ need to access a critical section. Consider the following synchronization construct used by both the processes Here, `varP` and `varQ` are shared variables and both are initialized to false. Which one of the following statements is true?

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Two processes XXX and YYY need to access a critical section. Consider the following synchronization construct used by both the processes Here, varP and varQ are shared variables and both are initialized to false. Which one of the following statements is true?

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Two processes XXX and YYY need to access a critical section. Consider the following synchronization construct used by both the processes Here, varP and varQ are shared variables and both are initialized to false. Which one of the following statements is true?

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Two processes $X$ and $Y$ need to access a critical section. Consider the following synchronization construct used by both the processes Here, `varP` and `varQ` are shared variables and both are initialized to false. Which one of the following statements is true?

Two processes $X$ and $Y$ need to access a critical section. Consider the following synchronization construct used by both the processes Here, `varP` and `varQ` are shared variables and both are initialized to false. Which one of the following statements is true?